9.20 Final
7. What is the "naturalistic fallacy" often made by people, including some scientists, who are opposed to sociobiology's studies of human nature? [Note: The philosophical expression of the naturalistic fallacy as a logical fallacy was described by the philosopher G.E. Moore (Principia Ethica, 1903). See Wikipedia, "Naturalistic fallacy".]
"An evolved tendency is natural, and therefore acceptable and justified." (See Q1 and Q2 above.) What "natural" human desires and tendencies have we talked about that are definitely not good for most people in modern societies? • Eating high sugar, high fat foods (especially saturated fats) • Eating high-salt foods all the time • Consuming alcohol in drinks or foods • Committing rape in wartime • Various illegal actions (e.g., theft from non relatives)
12. What is "genomic imprinting"?
"Genomic imprinting is the epigenetic phenomenon by which certain genes are expressed in a parent-oforigin-specific manner. If the allele inherited from the father is imprinted, it is thereby silenced, and only the allele from the mother is expressed. If the allele from the mother is imprinted, then only the allele from the father is expressed." "It is an epigenetic process that involves DNA methylation and histone methylation without altering the genetic sequence." What about human fetus sizes with the potential to damage or even kill the mother? It is (probably) not adaptive for the female, but it may be for the male. Without "genomic imprinting" it is hard to explain
14. In his studies of these warblers, the sociologist J. Komdeur (1997) made a surprising discovery: Females can regulate the sex of their offspring. Why has this ability evolved? Explain in terms of female fitness, and behavioral differences between male and female offspring. (p 126-127)
"Prior to the sociobiological era, no one checked whether birds could 'choose' which sex to produce in their offspring." On good territories, a "helper at the nest" is beneficial. Usually the helper is a daughter. On poor territories, there is insufficient food for the extra bird. Using sociobiological reasoning, Komdeur tested for the possibility that females can bias the sex of offspring, to increase the probability of getting a helper if she had a good territory. (Papers published in 1996, 1997.) RESULT: On poor territories, 77% males were hatched. On rich territories, 13% males were hatched.
What other questions could the scientists have asked? Include an example of a proximate question and an ultimate question.
"Proximate": questions: - What sensory cues is a beetle using to recognize other members of its species? (What are the key stimuli?) - Does this behavior vary with specific hormonal levels? Ultimate question: Does it increase the probability that an individual will be able to mate?
3. Why have many social scientists and people in the humanities ignored sociobiology? P 220- 221
"alien and disquieting" • Perceived conflict with ideology, including religious doctrines. • Fear of a "takeover" of their field by sociobiologists • Extreme environmentalism: rejection of nature with an exclusive emphasis on nurture.
Sexual selection in birds of paradise- Why do you think the elaboration of the male feathers has gone to such extremes these birds?
(Goldie's bird of paradise) (Peacock) - Few predators, if any. - The plumage does not interfere very much with their foraging & feeding. - Because the costs are not very great, males benefit by being attractive to the females—and the most attractive males are most likely to be chosen as a mate
A prime mover of social evolution is ecological pressure—specific ecological conditions that influence the evolution of specific patterns of social behavior. What are some examples related to anti-predator behavior?
*** 2) Examples related to foraging: • Groups/coalitions & cliques can increase competitive ability in feeding 2) Examples related to foraging: - Increased feeding efficiency by social behavior: • Imitative foraging: when food is not evenly distributed - Go where the group goes (seen in many birds and fish; they take advantage of the most experienced ones) - (In the case of birds) territories form when food is evenly distributed • Cooperative foraging - Feeding flocks form when food is in unpredictable patches. - Cf. pack-hunting mammals, ant cooperation, honeybee communication. - Large prey makes cooperative hunting more adaptive for carnivores.
Ecological pressure puts demands on foraging behavior. What kind of social interactions can increase competitive ability of individuals?
*****
Ecological pressures influence the evolution of other aspects of foraging. Give examples of how feeding efficiency can be increased by social behavior.
*****
Susan Brownmiller
- 1975 - Against Our Will, the "myths about rape"
William D. Hamilton
- Analysis of altruism in 1964, genetic consequences of extreme altruism (promote altruistic behavior of female worker insects towards sisters who are future queens - increases chances of reproduction of their own genes)
Describe at least one means by which sperm competition could occur after mating.
- Mate for a longer time period: • Produce more sperm, but also they occupy the female for a longer time period - Produce more energetic sperm that can beat the competition
Another concept in Wilson's chapter 4 is that of inbreeding taboos—a complex issue. What are the opposed selection tendencies related to kinship that affect sociality?
- Opposed selection tendencies affecting sociality: • Small groups of related individuals favor altruistic behavior and close cooperation • but inbreeding often lowers individual fitness, depresses performance, lowers genetic adaptability
David MacDonald
- Oxford University, study of farm cats, found that farm cats form societies made up of mostly related females to mutually aid in care of kittens and provide mutual defense against aggressive males
One of these is the coefficient of kinship—which is the same as the inbreeding coefficient. What does this coefficient mean, and how can it be calculated?
- Represents the probability that both alleles at one locus are identical because of common descent.
What are the conditions that make it likely in a species that mate choice will be exercised by the males?
- When males defend nest, there is a limit to the number of eggs/young he can defend. Therefore, a male cannot maximize reproduction just by indiscriminate mating. - When there are more females than males, male choice is more likely - especially if the male is in charge of the nest, as in stickleback fish
Dereck Freeman
- critiqued Margaret Mead
Franz Boas
- father of modern cultural anthropology, believed in the autonomy of culture (separate from biology, freeing human nature from evolutionary biology)
B. F. Skinner
- operant conditioning and behaviorism, claimed laws of reinforcement learning are universal
Thornhill
- papers on the topic of female cryptic choice and conflict between the sexes
David Barash
- report on mountain bluebirds, wanted to test male anti-cuckoldry behavior (keeping female from having EPCs), put stuffed male bluebird in territories of different male bluebirds at different times, both males attacked model and one attacked mate, concluded that aggression = confirms anti-cuckoldry behavior because presence of another male increases likelihood of EPC
Margaret Mead
- student of Franz Boas, cultural anthropologist, wrote Coming of Age in Samoa - 1928, popular but widely mistaken, claimed that culture shapes attitude (her example = attitude towards sex)
Diane Fossey
- study of wild mountain gorillas
13. Among Seychelles warblers what are the advantages for young birds if they help their parents rear siblings by becoming a "helper-at-the-nest"? (This is clearly a form of altruisim.) (p 123-124)
-- They gain experience -- They promote the survival of close relatives. -- They can inherit the territory. Helpers are usually female. They are used by adult pairs that have the better territories
1. What is the error of the false dichotomy that has often been used by persons arguing against the relevance of biology to an understanding of human behavior? (Such arguments have been common in writings of sociologists, cultural anthropologists, some feminists, and also some educators.) p 130
...either culture or biology... ...either learned or innate... ...either nature or nurture... A related error: Pitting two different kinds of hypotheses against each other—proximate and evolutionary (ultimate) hypotheses
Mate choice by females appears to be based, in general, on one of two properties of the males, or on both of these. What are they? Give an example of how a female of a particular species bases her choice on one of these traits. Give an example also of selection based on the other trait.
1) Material benefits - Resource provision: resource provision (male brings her food. Ex: hanging flies - female copulates for longer periods with larger male gift) or female can tell based on physical features that male has good genes (good forager, less likely to have parasites) - Other material benefit: • a male goldfinch with more brightly colored plumage has more carotenoids in his body, indicating that he is a good forager & less likely to have parasites 2) "Attractiveness"
9. See Appendix, ch 4: Q2. Male red-winged blackbirds are observed interfering with the foraging activity of mates that have engaged in EPCs with neighboring males. Hypothesis: this is adaptive because it enables males to reduce investment in offspring likely to carry another male's genes. Alcock proposes several questions concerning use of the comparative method to test this hypothesis. See p 226.
1) Must we restrict our comparisons to other members of the family (Icteridae) to which red-winged blackbirds belong? 2) Are bird species that are strictly monogamous of any use to us? 3) What about animals other than birds?
Evolution by natural selection is often summarized as evolution by "survival of the fittest." How is it, then, that in certain species of spiders (also in certain insects) the male is eaten by the female in the act of copulation?
1) The male is not likely to survive long enough to find a second mate 2) A well-fed female is less likely to mate again, so the male that was eaten is more likely to pass on his genes
16. See Appendix, Ch 6, Q 1. Alcock encourages discussion of step-parenting observed in some birds. You should invent ultimate hypotheses and also explanations in terms of proximate mechanisms. (Read Appendix Q 2 also because of the interesting phenomena described there—sex changes in certain fish.)
1)Benefits for his genetic fitness? • Future helper? • Future mating opportunities, when mates may be hard to find. 2)A result of proximate mechanisms operating in an abnormal situation.
What is the role of endogenous and exogenous signals in control of the activity rhythm of a mammal, e.g., a mouse, hamster or human? (4 points)
A circadian rhythm of activity is controlled by an endogenous "clock" but the phase of the rhythm is synchronized to the daily light-dark cycle, which keeps the rhythm at 24 hours. Without the exogenous signal, the activity rhythm would be (in most people) longer than 24 hours.
What is a "Darwinian puzzle"? Give an example, and also a solution to the puzzle.
A commonly seen behavioral characteristic or tendency that appears to reduce an individual's chances of reproducing successfully, even by a small degree, becomes a Darwinian puzzle. Example: Why do whirligig beetles congregate so much when large groups of them are attacked more often than smaller groups? - They also pay a price in reduced reproduction: However: - Attacks have been found to be lower per individual as group size increases. This outweighs the costs.
8. Define the "demographic transition" in human populations. It presents a Darwinian puzzle, for which the proposed solutions are incomplete.
A decline in average fertility began in several European countries in the late 1800s, and in a few others in the early 1900s. Thus, it began before the development of modern birth control methods.The demographic transition Observed reduction in female fertility: Are there fitness advantages? - Evolutionary advantages of timing of pregnancies - Advantages of acquiring wealth to pass on to children and grandchildren - Omitted in text: Effects of overcrowding, which include, in animal studies, reduction in fertility. - Also of great importance: Humans evolved under conditions of limited communication and relatively small group sizes. Rapid long distance communication and awareness of population sizes and their consequences is very recent in evolutionary time. Read Alcock's discussion of how traits that had evolved to improve genetic fitness have resulted in reduced genetic fitness in wealthier people, not only because of modern contraceptive methods but also because of legal restrictions.
What is "assortative mating" or homogamy?
A tendency to choose a mate that looks similar to oneself or one's close relatives
Which behavior of specific animals would challenge a Darwinian adaptationist (a sociobiologist) most? Study the four descriptions.
A. The ability of ...ocean-dwelling salmon to locate a distant stream by its scent in order to swim up the stream and breed. B. The readiness of some adult birds with offspring nearby to scream loudly when in the grasp of a predator. C. The discovery that when two or three extra eggs are added to the nest of some birds, the breeding adults successfully rear the additional offspring. D. The fact that some bats can locate and track down their prey, small flying insects, in complete darkness. The fitness benefits are easiest to understand for B and D. A. The arduous journey of an ocean-dwelling salmon to locate and swim up a stream in order to breed entails very high costs. C. Birds accept eggs from non-mates, even from another species, and care for them, feed the hatchlings, etc.
13. Other examples of recent publications related to this topic are not difficult to find. Describe several.
Abstract Modern humans have inherited the mating strategies that led to the success of their ancestors. These strategies include long-term mating, short-term mating, extra-pair mating, mate poaching, and mate guarding. This article presents empirical evidence supporting evolution-based hypotheses about the complexities of these mating strategies. Since men and women historically confronted different adaptive problems in the mating domain, the sexes differ profoundly in evolved strategic solutions. These differences include possessing different mate preferences, different desires for short-term mating, and differences in the triggers that evoke sexual jealousy. The study of human mating is one of the "success stories" of evolutionary psychology. Abstract The existence of a beauty premium in the labor market and the male- female wage gap suggests that appearance can matter in the real world. We explore beauty and gender in a public goods experiment and find similar effects. We find a beauty premium, even though beautiful people contribute, on average, no more or less than others. The beauty premium, however, disappears when we provide information on individual contributions, and becomes a beauty penalty. Players seem to expect beautiful people to be more cooperative. Relative to these expectations, they appear more selfish, which in turn results in less cooperation by others. These appear to be clear examples of stereotyping. We also find a substantial benefit to being male, especially with information. This is primarily due to men being better ''leaders.'' Men tend to make large contributions, and people follow their example and give more in later rounds.
9. See Appendix, ch 8, Q1: "A substantial proportion of rapists...(perhaps a third) fail to ejaculate in the victim. Does this finding enable us to refute sociobiological explanations of rape? ..."
Actually 2/3 do not fail to ejaculate, so sociobiological explanations are not refuted. "Barbara Ehrenreich says that because the children sired by rapists in the past surely were more likely to die than those of paternal nonrapists, rape cannot possible be an evolved adaptation [Time, 2000]. Is she correct? Why might she make this claim?" Not a good argument because many do survive. She may make the claim because she does not want anyone to consider rape as "natural" behavior.
George C. Williams
Adaptation and Natural Selection - 1966, how evolution works: evolved adaptations are extremely unlikely to promote long-term advance of the species at the expense of individual reproduction; publication was part of the shift in emphasis from proximate causation to ultimate causation in 1970
What kind of predator poses the greatest threat to kittiwakes? (1 point)
Aerial raptors (birds of prey) [eagles, hawks, falcons], also other birds [like gulls sometimes attacked the nests to get eggs].
Explain why Alcock spends so much time (space) on discussion of a short preliminary report by David Barash on mountain bluebirds.
Alcock uses this as an example of the controversies about sociobiology (S.J. Gould's attack on Barash's 1976 "scientific note") What Barash did • He wanted to test the hypothesis that a male mountain bluebird should show anti-cuckoldry behaviors in order to increase the probability of his being the father of chicks hatched in the nest of his partner and himself. • He conducted a small, preliminary experiment to test this, by placing a stuffed male bluebird into the territories of two male bluebirds at various times in the reproductive cycle and observing their responses. • The results were that each of the two males attacked the models, and one also attacked his mate. The intensity of these aggressive responses was greatest just before the first egg was laid. • Barash concluded that the aggressive responses confirmed the evolution of anti-cuckoldry behavior since the presence of another male in a male's territory increased the probability of extra-pair copulations, and also that driving an unfaithful mate away would allow the male to acquire another mate if females were sufficiently plentiful. Contrary to Gould's claim, Barash's hypothesis was testable, and it led others to test it further (with only partial support). Moreover, it led to much interest in EPCs (extra-pair copulations), mostly in birds.
10. Would Alcock's sex education class, designed to reduce the incidence of rape, really work? Why or why not?
Alcock's fantasy of a sex education class, teaching young people about sociobiolgical findings on sex differences in mating strategies: Would it actually work? • I believe that it would work only for true intellectuals: those whose knowledge and reasoning actually influence their behavior. • Such true intellectuals are very rare, hence, the class would most likely be a failure at most schools, if not all. (A true intellectual, as the term is used here, means a person whose knowledge actually affects her/his behavior, so when he or she gains knowledge that behavior can change.)
Wynne-Edwards
Animal Dispersion in Relation to Social Behavior - 1962, how evolution works: interpreted almost every aspect of social behavior to be altruistic self-sacrifice that advances the welfare of the species
Describe evidence for thinking in apes from studies of "insight" learning. (4 points)
Apes are in an enclosure containing various boxes, and bananas are hung above the enclosure so they are too high for the apes to reach from the ground. If an ape piles the boxes up beneath the bananas and then immediately climbs on the boxes to reach them, it indicates insight learning. Alternative: The enclosure contains sticks that can be put together to form longer sticks, and a banana is placed outside the enclosure at a distance too far to be reached by a single stick. If an ape discovers how to put two sticks together to make a longer stick and then immediately uses the longer stick to reach the banana, it indicates insight learning.
What is wrong with the arguments presented by Robert Ardrey in his book, The Territorial Imperative ?
Ardrey argued from the widespread occurrence of territoriality in non-human animals that humans have territorial instincts. However, his assumptions were not correct: • Territoriality is far from universal in animals • Territorial practices of humans vary widely from culture to culture. Hence, most biologists did not take Ardrey seriously.
4. Learning mechanisms have evolved in order to increase fitness - to increase the likelihood that an individual's genes will be reproduced. As a result, these mechanisms are less general than many learning theorists have claimed. Give an example, from the learning of ingestion-related behavior in rats as studied by John Garcia. (p 162)
B.F. Skinner's laws of reinforcement learning, claimed to be universal, are violated in the poisoned bait effect. (How is this kind of learning different?) Also, note that different kinds of negative reinforcement have very different consequences in the learning of food preferences, studied in rats: • Electric shock to the skin after ingestion has little effect on future preferences. • After the rat eats or drinks something, X-ray exposure that makes the rat feel sick results in the animal's avoidance of the substance subsequently.
How did the evolutionary analysis of behavior begin?
Beginnings of the science: • Charles Darwin (1859), On the origin of species. • Charles Darwin (1872), The expression of the emotions in man and animals • Note: Alfred Russel Wallace independently discovered the process of natural selection, which goaded Darwin into action. Darwin's strong evidence, together with his arguments, firmly established the theory of evolution by natural selection. It is sometimes called the Darwin-Wallace theory.
6. What important kind of data on male-female differences is not mentioned by Alcock (p 204f)?
Behavioral differences (on average), with brain correlates, found by neuropsychologists in the following areas - Verbal abilities - Spatial abilities - Linear logic; quantitative analysis - Social and emotional intelligence and sensitivities females > males males > females males > females females > males Remember that these differences are not about "always". They are about statistical differences.
4. Why are studies of the behavior of white-fronted bee-eaters (birds) relevant to human behavior? P 196-201
Both species have families that persist over long time periods - so they have had similar selective pressures. The helping by "helpers at the nest" is by offspring, usually full siblings (sharing about 50% of genes) • How beneficial is the helping? See figure, p 198 - 3 adults needed for 1 surviving chick; 5 adults for 2 surviving chicks • What conflicts arise? (Father with male offspring) • What happens when a female mate dies? - If the male gets another female mate, how does his male "helper" respond? The answers to these questions have parallels in human behavior
5. Give two or three examples of the channeled nature of learning abilities in humans. Also, give examples of special ("channeled") abilities in animals. (p 167f, 171-173)
Channeled nature of learning abilities Humans: Language acquisition Anticipation of the actions of another person, with a sense of the other's intentions Learning of faces for later recognition Which of these abilities are shared with other animals, especially primates? Animals: Bird song learning (as studied in white-crowned sparrows and in zebra finches) Ability to find specific places by birds that cache food supplies (also done by mice and some other animals) Maze learning by rats, adapted to living in complex tunnels Etc.
Pavlov, I.
Classical conditioning
How does a command neuron differ from a motor neuron? (2 points)
Command neurons- activate coordinated sequence of movements Motor neuron- activate a muscle twitch
Garcia, John
Conditioned taste aversion is a unique kind of learning
How could Jim Corbett follow the movements of a leopard through the nearby jungle although he could not see it through the foliage?
Corbett listened to the sound of the racket-tailed drongo, a bird that can imitate the sounds of other birds and the cheetal. A leopard had just killed a cheetal, so the drongo was imitating the cheetal's alarm call. Corbett was able to follow the movements of the leopard by listening to the drongo, who was watching the leopard from above.
The physical guarding of his mate by a male can greatly reduce the chances of extrapair copulations. What other methods of preventing fertilization by another male have been found in some species?
Crabs in which the male's ejaculate forms a "sperm plug" Male dunnocks and "last sperm precedence" Cloacal pecking by the male before copulation Sperm removal by male invertebrates
How has strong evidence been obtained showing that kittiwake gulls are monogamous with only rare exceptions? (2 points)
DNA fingerprinting of nestings and adults rearing them showed that in almost all cases, the young were the offspring of both the male as well as the female at the nest.
Describe a simple experiment that could demonstrate an "appetite for aggression"—i.e., it must provide evidence of a specific motivation to engage in aggressive behavior. (4 points)
Design a two-choice apparatus, where one of the choices is an opportunity to confront a conspecific that the animal will try to threaten or attack. If the animal learns to consistently make the choice of the opportunity to show aggression rather than the other choice—which results in a physically similar situation without the presence of the conspecific—then the motivation for aggression is clear.
Was their question "proximate" or "ultimate" in nature, as these terms are defined by Alcock? What simple sociobiological experiment on the function of aggregations of whirligig beetles was carried out by Watt and Chapman, and what was the result?
Different sized groups of whirligigs were exposed to fish predators, capture rate per group and per individual were estimated. Attack rate per group increased with group size, suggesting that these aggregations behave as selfish herds. In another series of experiments in which whirligigs were exposed to top- and side-attacking predators, large groups were found to detect predators when they were further away than small groups. It was "ultimate" in nature: - How is the behavior adaptive? I.e., how does it increase the probability that an individual will reproduce successfully? • Does it reduce the chances of an individual's capture by a predator? • They answered this question experimentally, as described by Alcock.
Define "displacement activity." In what two situations do displacement activities occur? (5 points)
Displacement activity is an action that differs from the action or actions the animal or person is highly motivated to perform. It can occur in • situation 1, when the level of a particular motivation is high but the stimuli that would release the fixed motor pattern(s) are absent; or in • situation 2, when the levels of two different motivations are high, and the animal engages in a third action.
In a laboratory setting, it is much easier to test a hamster's visual orienting responses during the daylight hours, but not during the animal's most active period, including the final two hours of light. This may seem counter-intuitive (since it is not the hamster's most active period). Explain how it nevertheless makes good sense, from the standpoint of the hamster's adaptations. (3 points)
During the most active period, the hamster is much more sensitive to predators—its antipredator motivations are at a much higher level. These will dominate its behavior, making testing or orienting responses much more difficult or impossible. (The animal will spend much of its time freezing in response to any new sound or movement, and it is likely to run for cover at minimal provocation.)
To discuss inbreeding taboos, Wilson defines the "effective population number" and a model called "Wright's island model." Describe these.
Effective population number - the number of individuals in an ideal, randomly breeding population with 1:1 sex ratio which would have the same rate of heterozygosity decrease as the real population under consideration ‡ Wright's island model - Wright's model found advantages when a large population was composed of multiple smaller demes, each having at least the effective population number: There is more genetic variability between groups, so the population is better able to adapt to environmental changes
Flynn, John
Electrical stimulation of brain to elicit innate behaviors
Von Holst, E
Electrical stimulation of brain to elicit innate behaviors
Darwin, C.
Evolution of body structures and some behaviors by natural selection
What is the primary analytical tool of a sociobiologist?
Evolutionary theory: Sociobiologists want to know why natural selection led to the evolution of the social structure or behavior they are studying.
Explain the difficulty of separating in vacuo reactions from extreme threshold lowering, after describing an example of each. (6 points)
Example of an in vacuo reaction: An in vacuo reaction is defined as the build up of drive to do an action because of deprivation. For example, Lorenz's pet starling began to catch and feed on insects that did not exist. This was because the starling was kept indoors and became deprived of the opportunity to search for and feed on insects, and in this case the build up of drive caused the starling to carry out the behavior without insects present. Example of extreme threshold lowering: A very broad example is the idea that in great hunger there is less selectivity in foods chosen. Lorenz cites a quote that says "Other food lacking, the devil eats flies." Defined, extreme threshold lowering is when minimal stimuli become effective with a very strong drive, and the internal build up of drive "spills over." In this situation, with the need for stimulation, an organism will accept a stimulus that is not quite up to standard. Difficulty in separating these two: The difficulty in separating an in vacuo reaction and extreme threshold lowering is that both actions occur because of lack of the performance of a certain behavior and therefore are caused by very similar reasons. Also, it is very difficult to set apart the stimuli that charge up readiness to do something and the stimuli that set the behavior going.
Contrast proximate mechanisms/causes and ultimate outcomes for a specific behavior.
Example: Human desire to eat high fat, sweet foods What are advantages of fat and sweet foods? Fats contain a higher concentration of energy than other foods; sugars raise blood glucose, and thus available energy, very rapidly. Ultimate causes: Evolved to increase genetic fitness, and genetic fitness does not involve long-term survival, at least, not very much. Proximate causes: desirable taste, brain and hormonal mechanisms related to hunger and feeding
12. See Appendix ch 8, Q3: Reactions against socio-biological hypotheses that men have a predisposition to seek out multiple sexual partners of high fertility: a. Richard Lewontin: "I'm a man, and I don't go around screwing young girls. I'm human, and so I have to be explained." Why would a sociobiologist not be impressed by this criticism? b. Some men claim loudly that they are monogamous: How might a sociobiologist explain why this occurs?
Explaining reactions against sociobiologists' hypotheses • Answering Lewontin, from a sociobiological perspective: - Sociobiology is not about "always"; its findings are not disproved by "sometimes". • Why might a man proclaim loudly that he is monogamous? - It might convince his mate to be so too, so she will have only his kids. - It may give the man more influence/ power in social groups. - The "loudly" is suspicious: He may be doing that to get his neighbors to lower their guard.
1. The first paragraphs of this final chapter are a beautifully concise summary of a major argument of the book. Comment on the following sentence: "In fact, they could not study 'genetically determined' behavior even if they wanted to because it does not exist...." Is this too extreme? Use examples in your answer. P 217
First, behavior is only indirectly influenced by genes, as it is determined by the activity of the nervous system. That n.s. developed according to genetic information and with influences from the tissue and external environments. • Nevertheless, I think the statement is too extreme, because some behaviors have very little variation attributable to learning or other influences of the external environment: e.g., sneezing, yawning, withdrawal reflexes; grooming in mice; social signals in geese; various insect behaviors, etc. These behaviors are either reflexes or, on the output side, fixed motor patterns. • Thus, we can say that some behaviors are largely (but not totally) "genetically determined."
Explain exactly how the relative frequency of alleles B and b in Q3 could change (what could cause them to change) over multiple generations. (image on desktop)
For example, "B" could increase and "b" decrease in frequency for various reasons: • If b resulted in death before the age of reproduction more often than B • If b resulted in a behavioral difference that reduced the probability of successful reproduction in a particular environment, but not in other environments • If b resulted in no change in probability of reproduction, but it resulted in reduced parental care • Etc.
Tinbergen, N.
Founder of the science of ethology Distinguished four distinct questions asked by animal behaviorists
Lorenz, K.
Founder of the science of ethology The social organization of geese
2. Summarize Derek Freeman's critique of the writing of Margaret Mead, the cultural anthropologist whose ideas presented in her 1928 book, Coming of Age in Samoa, became so popular in the 20th century. p 132-133
Freeman published a book in 1983 critical of Mead. He dealt with the following questions: • What did she claim? (The claims turned out to be much too extreme.) • How did she come to believe these claims? • Why did she make such errors? What did she claim? Samoan society is very different from American society in having relaxed attitudes towards premarital sex by young women, and in the absence of rape and freedom from emotional turbulence during adolescence. • How did she come to believe these claims? At age 23, she had been told this story by another cultural anthropologist and wanted to verify it. She learned the basics of the language, went to Samoa and spent 12 weeks questioning a group of 25 young women. Also, remember that her teacher was Frank Boas, whose beliefs she had accepted. Why did she make such errors? − She did not remain in Samoa for extensive observations, and believed what the girls told her too easily. They were often kidding her. She heard what she wanted to hear. − Remember also that she was imbued with the beliefs of her teacher, and of many others in America, that humans are products of their culture, not their biology. − The arguments of Frank Boas are the same as those that have been faced by sociobiologists when they have applied their ideas and methods to humans In summary, Margaret Mead tried to do a scientific study, but she made big mistakes. • She published a popular book that had a wide influence despite the errors. These errors did not become known for certain for many years.
8. Why have male fruit flies evolved so they inject chemicals that harm their mate, chemicals injected along with their sperm? Explain in terms of evolutionary "fitness", following the logic of G.C. Williams (1966). (p 109-112)
From the perspective of the male, what counts is the number of eggs capable of hatching that he inseminates. It is in the interests of his genes to destroy sperm from other males, even if this entails reducing the genetic fitness of the female—by shortening her life or by reducing the total number of her eggs (as long as this reduction is not extreme).
What is the difference between genetic determination of behavioral traits and sociobiologists' views concerning genes and behavior?
Genetic determination of behavior- genes determine the development of specific social behaviors? Sociobiologists' views: - FAPs occur when the level of motivation exceeds a certain level, which is influenced by many environmental variables. - "nature-nurture" problem: Both are always involved, even in the case of FAPs.
5. Why did Trivers and Hare (1976) predict that in colonies of social insects, workers would care more for future queens than for future drones (males)? (p 101)
Genetics of the social Hymenoptera (See p 96-97 on Hamilton; also fig 6.1, and p 101 top): Fertilized eggs produce females; Unfertilized eggs produce males. One result: A female is more closely related to her sisters than she is to her daughters as well as to her brothers. Thus, a female worker's genetic fitness benefits more if she raises sisters than if she raises brothers or daughters. This reveals a possible reason why a sterile worker caste could evolve, but there are alternative reasons as well, as mentioned earlier
Statement by Stephen Jay Gould: "An evolutionary speculation can only help if it teaches us something we don't know already—if, for example, we learned that genocide was biologically enjoined by certain genes" (Natural History, 1996) Why does this illustrate a failure to distinguish proximate and ultimate causes?
Gould's example shows his concern for proximate causes—and seems to assume that specific genes cause a specific pattern of behavior. This is not what sociobiologists claim. They look for inherited tendencies and their functions, explaining such tendencies in terms of past evolutionary pressures that caused such tendencies to emerge. They do not claim that any specific genes can cause a complex behavior. They look for ultimate causes, not the proximate mechanisms underlying a behavior. (Proximate mechanisms include the genetic control of brain development and the resulting behavioral patterns.)
What is the main advantage of a "giant axon" in the triggering of an escape response, as in a squid or crayfish? (1 point)
Greater speed of axon conduction, resulting in greater speed of the escape response.
9. Explain the evolutionary logic of the mating behavior of hanging flies studied by Randy Thornhill (1976). Why does the male present the receptive female with a gift of food, like a dead moth, and why does the gift have to be above a certain size to be most effective? (p 113-115) [This came up in class previously]
Hanging flies, findings of Thornhill (1976): • If the food is all eaten before the male has finished, or even begun, transferring sperm, the female uncouples and flies off to find a male with a larger food offering. • After the sperm transfer is complete (in 20-25 min), the male and female often fight for what remains of the food. • CONCLUSION: The interaction between male and female hanging flies is "marked with genetic conflict, as each individual jockeys for maximum personal reproductive gain and thus maximum genetic success." Mate choice by females, after Thornhill (and Williams): "Thornhill's papers on the topic of female choice and conflict between the sexes marked the start of an era, still continuing, in which these issues have been actively explored. A battalion of adaptationists who have adopted the gene-counting view of evolution are asking questions such as the following: "How do female mating decisions promote the propagation of their genes? "What exactly do females (and their genes) gain when females reject some males in favor of others? "How do males manage to compete with rival males in a game whose rules were established by females?" (Alcock, p 115)
Why would evolutionary biologists (like sociobiologists) object to the speculative argument of Marvin Harris about the origins of human warfare?
Harris, a cultural anthropologist, argued that human warfare "stems from the inability of preindustrial peoples to develop a less costly or more benign means of achieving low population densities and low rates of population growth" needed to prevent overexploitation of essential resources. Harris' view does not conform to how evolution actually works. He makes species benefits more important than benefits to the individual.
Describe a situation that makes monogamy much more likely. Use an example with an explanation.
Harsh conditions (e.g. very cold; limited food) When encounters are rare (e.g. Deep-sea angler fish: They are sit-and-wait predators. When a pair does meet, the male attaches himself to the female as a parasite.)
Did E. O. Wilson invent the field of Sociobiology? What were the antecedants? What was Wilson's primary field of basic research in biology?
He invented the word, and synthesized the field. • His review and arguments were forceful, and promoted the importance of research on "ultimate" issues in social behavior. • Wilson was an entomologist, studying the behavior of social insects. (Now he has broadened his studies, and is a major promoter of conservation efforts and the importance of biodiversity.)
What is meant by the "prime movers of social evolution"—the title of chapter 3 in E. O. Wilson's Sociobiology?
He means the major factors that speed up or slow down evolutionary changes in social behavior. For example: - Reduced genetic variation and "genetic swamping" slow it down.
Karl von Frisch
Honeybees dance in the hive to communicate the location of nectar and pollen sources (waggle dance)
Describe one study supporting the adaptationist claim that EPCs by female red-winged blackbirds are adaptive.
Hypothesis: Extra-pair matings are adaptive for a female because they reduce the likelihood of laying infertile, and hence wasted, eggs. Test by Elizabeth Gray: 1% of eggs from clutches sired by 2+ males failed to hatch. 6% of eggs from clutches sired by the male mate alone failed to hatch. This difference was statistically significant. The test gives evidence that for the female, the EPCs were adaptive, but they were probably not adaptive for the male mate.
Are female red-winged blackbirds adaptively selective in their choice of a male for EPC?
Hypothesis: Males visited by females for EPC have unusual attributes, promising in an adaptive sense, relative to males that are not favored for EPCs. Observations • Female red-wings appear to choose older over younger males in the neighborhood (studies by Patrick Weatherhead and his group). • Observations on other songbirds: Females make such choices in non-random fashion, preferring males that have found mates early in the mating season, indicating that they had attributes making them more attractive.
A research team from Emory University has succeeded in transferring a particular gene from prairie voles, which are monogamous, to laboratory mice, which are typically promiscuous. Males of the genetically altered mice exhibited a much stronger attachment to their mates (provided the males also received an injection of the hormone vasopressin) than unaltered controls. Would it be wrong to say that the work demonstrates that prairie vole males possess a 'gene for monogamous behavior'? Explain what the phrase would have to mean in order to be accurate.
If this is taken literally, it would have to mean that a single gene can control the behavior. This is never true. • The influence of genes on behavior is never a direct one. • A behavior like monogamous mating depends on the influence of multiple genes.
How have the scientific fields concerned with animal behavior changed since Wilson's 1975 book?
Image on desktop
9. Answer Q1 in the Appendix for ch 9: "Imagine that someone [a sociobiologist] establishes that the maternal drive of women is on average greater than the paternal drive of men across most societies. Imagine that an adaptationist proposes ...[an explanation in terms of genetic fitness]" Is the sociobiolgist being irresponsible...[since people may misuse his conclusions]?
Imagine that someone establishes that the maternal drive of women is on average greater than the paternal drive of men across most societies. Imagine that an adaptationist proposes that this result arises because in past environments men that took time and energy from paternal activities and allocated them to the acquisition of mates gained fitness as a result, whereas women who did the same lost fitness relative to those who invested more into maternal care of their offspring. Is the sociobiologist being irresponsible, given that his hypothesis may be invoked by those who believe that women should stay home with their children while men earn income in the workplace?
7. What is "evolutionary psychology" and how is it distinguished from sociobiology?
Includes a strong critique of an aspect he perceives in sociobiology. "To quote one well-known sociobiologist, 'Humans are inclusive fitness maximizing blobs' (Alexander, 1991). I have labeled this view the sociobiological fallacy (Buss, 1991) because it conflates a theory of the origins of mechanisms (inclusive-fitness theory) with a theory of the nature of those mechanisms. If men had as a goal the maximization of fitness, then why aren't they all lined up to give donations to sperm banks, and why do some individuals decide to forgo reproduction entirely?" Does Buss really characterize sociobiologists accurately?Buss quotes Tooby & Cosmides, well-known evolutionary psychologists: "The nature of mechanisms as end products should not be confused with the causal process that created them. The sociobiological fallacy has led to some dubious speculating about how, if one really looks closely enough, one will see that person X really is maximizing fitness, even though the behavior seems anomalous with respect to this goal (e.g., suicidal, schizophrenic, dysfunctional). Evolutionary psychologists see humans as "adaptation executors" or "mechanism activators" rather than as "fitness strivers" (Tooby & Cosmides, 1990b)." This is similar to what Alcock has stated in his book. Ultimate and proximate causes are quite separate. Thus, Buss goes too far in his critique of sociobiology.Thus, an evolutionary psychologist likes to focus on studies of psychological mechanisms (proximate in nature), and is influenced by ultimate causes as well.
5. Appendix ch 10, Q3. Ian Tattersall describes how women in a surviving hunter-gatherer tribe breast-feed their infants for four or more years, a practice that blocks ovulation during this time and prevents them from becoming pregnant. He writes, "Their genes hardly seem to be screaming out for replication; and economic considerations, as virtually always, lie to the fore. For hunters and gatherers, then, it's fertility, not its lack, that is the enemy. Individual San women show no sign, conscious or unconscious, of wishing to maximize their output of progeny." Tattersall believes that he has identified a major weakness of sociobiology. Is he right?
Individual awareness concerns proximate mechanisms, not evolved adaptations. • There are fitness-enhancing advantages of spacing of offspring - Tattersall is wrong about fertility itself being the enemy. • There are other benefits of breast feeding: - Mother-child bonding, which promotes the welfare of the child, thereby increasing its potential for reproduction. - Transfer of immunities when the infant's immune system is not yet mature
Define infradian and ultradian rhythms
Infradian: cycle >24 hrs Ultradian: cycle <24 hrs
Lettvin, J.Y.
Innate releasing mechanisms found in frogs using microelectrodes
In cases where there is a pair of kittiwake chicks in a single nest and one of the chicks is larger and more aggressive than the other one, how might the weaker chick survive when its nestmate becomes dominant enough to get most of the food? (2 points)
It can sometimes move to a neighboring nest, where the adults will often adopt the chick.
What is the nature of the language called "Equus" by Monty Roberts? He put his knowledge of this language to use in developing a new method of training wild horses. (2 points)
It is a kind of sign language, almost completely visual. The horse uses and interprets eye and head direction, the angle of the body axis with respect to the position of the observer, the position of the ears, how high the head is held, etc.
How could a gene that has what appear to be maladaptive consequences be present in some animals or people today? Why has it not been lost?
It is a recent mutation, and will be lost; or it has its bad effects after reproduction; or it has its effects only in certain environments, and otherwise has benefits. Modern medical treatments Genetic swamping—This interacts with the above factors
Sociobiology has often been deprecated by recitation of the "myth of the deterministic sociobiologist." Give some reasons why this myth has been so enduring since the publication of E.O. Wilson's book that gave the field its name.
It is enduring despite the fact that all biologists know that every trait of every organism develops through an interaction between genes and environment. • It is the nature of human psychology: We believe in our ability to change our behavior, and other people's behavior. • For some, the flexibility of human behavior is "mistakenly taken as evidence that cultural factors are the only real determinants of our actions." (This view is especially common among cultural anthropologists.) • Championing free will and freedom of action is understandably popular: Humans appear to have evolved an enthusiasm for freedom of action, with a belief in free will. We all feel that we have freedom of action.
10. Stephan Jay Gould has written a critique of evolutionary psychology in which he claims, "Men are not programmed by genes to maximize matings, nor are women devoted to monogomy by unalterable nature. We can speak only of capacities, not requirements or even determining propensities. Therefore, our biology does not make us do it" (1996). Analyze this criticism of sociobiology in the context of the culture versus biology dichotomy. (We have dealt with such questions previously.)
It is not an either-or matter. Critique of Alcock p 147: In the final paragraph of chapter 7, Alcock sums up his conclusions about the "unlikely philosophy that Gould, Mead, and many social scientists and some feminists would have us accept largely on ideological grounds." Then he suddenly shifts the argument: "That this position has any residual credibility can be attributed largely to the power of wishful thinking that some special meaning accrues to human existence." He continues with a quotation: "It is not easy to accept that evolution is a 'meaningless tale told by an idiot'." His conclusion is then stated: "Indeed, most people find it hard to believe that blind evolutionary processes have created us, a creature whose unconscious ultimate goal is no different from that of the slime mold, the aardvark, the pine tree, and the earthworm. Although this point is evidently unpalatable, it is true nonetheless." Critique of Alcock p 147: Note his narrow definition of "ultimate goal"—in terms of the simple rule of evolution and genetic fitness. Is evolution a "meaningless tale told by an idiot"? (I find this extreme statement to be an unnecessary conclusion.) In my view, what is really incredible and amazing is that the simple and repeated process of genetic spread and change, following the biological law of natural selection, has led to such complex creatures with such cognitive capacities and with such an ability to ponder the nature of the world and its beings.Is the simple rule driving evolutionary change a reliable guide to human morality (or law)?
For Innate Releasing Mechanisms, what is the usual role of learning? (1 point)
It makes the mechanism more specific.
7. What is the explanation for why a male damselfly stays near a female he has first mated with rather than fly off in search of other females to mate with? What did G. A. Parker, in 1970, call this type of phenomenon? Would you expect it to be widespread across various species? (pp 104-109)
John Alcock, The Triumph of Sociobiology, ch 6: p 104f What did G. A. Parker, in 1970, call this type of phenomenon? "Mate guarding": not to help her but to prevent her from mating with other males. Would you expect it to be widespread across various species? Yes, if the females remain receptive after mating and can still be impregnated. (This has been verified.)
1. Explain the statement (p 150), that "the brain is essentially a reproductive organ...."
Like every other organ or mechanism that living things are born with, since they have evolved largely by the processes of natural selection—based on the maximal transmission of genes.
"Humans and chimps are, after all, the only species among the 4000 species of mammals in which male relatives form groups to raid other groups while living in and defending the area of their birth." Where would you look for possible exceptions to this claim?
Look in other mammalian groups with similar social organization (e.g., dolphins)—but we have inadequate information on cetaceans, as well as on many other mammalian groups. Questions: Is the behavior adaptive, so it could have evolved by natural selection? (If so, should it not be more common?) Suggestion: Warfare among human nations stems from conflicts between the much smaller human tribes and villages that predominated during most of human evolution. Nationalism is loyalty to the group: This was once only loyalty to the much smaller groups that were mostly relatives. The evolution occurred before the invention of modern weapons. What once was probably adaptive is no longer so. • Wars among birds: the egg wars - Parasitic birds: cowbirds, cuckoos, and cuckoo finches have incited host birds to fight back • Yellow warblers vs. brown-headed cowbirds: burying of the eggs when a cowbird egg is found • Reed warblers will mob cuckoos; the commotion alerts other reed warblers to be extra vigilant • Cuckoo mafia tactics against starlings (previously noted)
Describe evidence that gestures of threat have originated from superpositions. (4 points)
Lorenz produced a table showing drawings of a dog showing increasing motivation to attack along one axis, and increasing motivation to retreat on another axis. Pictures of dogs showing high levels of both of these motivations show a super position of the two expressions, and indicate the mood of threat.
2. What view of evolution was presented by the famous ethologist Konrad Lorenz in his 1966 book, On Aggression, a view of Darwinion theory that has been rejected by sociobiologists? Why did this mistake not impede K.L. in his major studies?
Lorenz wrote about species benefits, contrary to George C. Williams* (1966) who argued for the dominance in evolution of individual benefits, meaning the survival and propagation of specific genes carried by the individual. Why did this mistake not impede K.L. in his major studies? Lorenz focused on proximate questions. From Lorenz' writings about evolution: • In his book On Aggression (1966), his theoretical orientation was "group selectionist". • In his 1981 book, when he discussed purpose in evolution, he wrote, e.g., "...its explicit function was selected ... because of its species-preserving value" (p 29 in The Foundations of Ethology, 1981). • However, when he writes about genetic variation, he discusses the survival of individuals (p 26), and quotes Eigen (1975), "Life is a game in which nothing is stipulated but the rules."This was at least slightly similar to E.O. Wilson (1975, 1980), on "the morality of the gene" • "In a Darwinian sense the organism does not live for itself. Its primary function is not even to reproduce other organisms; it reproduces genes, and it serves as their temporary carrier" (1980, p 3). - At first this may seem ridiculous—until you realize that "purpose" or "function" from the standpoint of biological evolution is very restricted. Evolution follows a blind and simple rule. - When we think about consciousness and the great ontological questions, we place ourselves outside the realm of that rule. • The brain centers that "flood our consciousness with all the emotions— hate, love, guilt, fear, and others" have evolved by natural selection. The "hypothalamus and limbic system are engineered to perpetuate DNA." • But Wilson is also "group selectionist," albeit in a way that comprehends molecular genetics: Review the quotations on next slide From E.O. Wilson, Sociobiology, the abridged edition (1980) • The hypothalamic-limbic complex of a highly social species, such as man, "knows," or more precisely it has been programmed to perform as if it knows, that its underlying genes will be proliferated maximally only if it orchestrates behavioral responses that bring into play an efficient mixture of personal survival, reproduction, and altruism. Consequently, the centers of the [brain] complex tax the conscious mind with ambivalences whenever the organisms encounter stressful situations. Love joins hate; aggression, fear; expansiveness, withdrawal; and so on—in blends designed not to promote the happiness and survival of the individual, but to favor the maximum transmission of the controlling genes. (p 3-4) • The ambivalences stem from counteracting pressures on the units of natural selection. ...what is good for the individual can be destructive to the family; what preserves the family can be harsh on both the individual and the tribe to which its family belongs; what promotes the tribe can weaken the family and destroy the individual; and so on upward through the permutations of levels of organization. (p 4) - This shows his inclusion of group selection ideas
Describe the courtship behavior of the male water mite (Neumania pupillator, described by Scott) or of the male water strider, and how it must have evolved as an exploitation of an innate releasing mechanism of the female. (4 points)
Males of both of these small insects have a similar strategy, which must have evolved from their attraction to a certain prey animal: They use their front legs to make vibrations in the water that are very similar to those created by their usual prey. This attracts the female, and when she approaches, the male can copulate with her. At least in the case of the water strider, this copulation is forced.
2. What explanations for fitness-reducing behaviors have been offered by sociobiologists? P 218-219
Many of these behaviors are altruistic ones. Most altruism has been shown to be adaptive, either directly (involving genetic relatives) or indirectly (reciprocal altruism). Maladaptive altruism also occurs, and has potential explanations, e.g., • By-product hypothesis (There are behavioral by-products of proximate mechanisms that evolved for adaptive reasons.) • Novel environment hypothesis (Some behaviors were originally adaptive but the environment has changed and made them not so adaptive.)
3. Give an example of a medical issue that can be illumined by sociobiological ideas and data. P 195-196
Morning sickness (discussed by Alcock) Fever Pain Each of these has been found to have fitness benefits in a sociobiological sense.
Which kind of question (proximate or ultimate) is more important?
Neither, it depends on the purpose pursued by the scientist.
Name and define the different mating systems. How is the answer expressed by Nick Davies based on his studies of the reproductive behavior of the dunnock, a small European songbird (the hedge sparrow)?
Nick Davies et al: • We should view the mating game not as a cooperation between the sexes but as a conflict resulting in a compromise in the interests of one or both of them • Monogamy (social; genetic) • Polygyny: 1 male, >1 female • Polyandry: 1 female, >1 male
3. Contrast the "blank slate" view of human nature with sociobiological views. What do "blank slate" views of human nature predict about social structure and practices? p 134 - 136
Note how much more difficult it is to make believable predictions like this for non-human animals than it is for humans.We have discussed this issue previously. • Note two new things here: - Gould's claim about "biological potentiality" vs "biological determinism": He claimed that a human has "a brain capable of a full range of human behaviors and predisposed toward none" - Lack of rigorous tests of predictions of cultural determinism. Alcock suggests some predictions the critics should be testing: "Human behavior should differ greatly and arbitrarily from society to society." He gives examples. (p 135-136) • Do you agree with Alcock's arguments—in part or completely?
Interpret figure 3.1 by explaining how a difference in one allele (B vs b) could result in a behavioral difference between two adults.
Note that the figure depicts a kind of multiplier effect—because of the long period of development during which the genetic difference interacts with various environmental influences. In looking at the figure, think of the differences between hygienic and non-hygienic bees. • Both types of bees may inherit the same behavioral repertoire. • They may differ only (or mainly) in their olfactory sensitivity. • One gene difference could affect olfactory sensitivity and result in bees being hygienic, or non-hygienic. • This reasoning may apply to many differences in behavior—differences we call "genetic"
Opposition to sociobiology
Often, the arguments are against biology altogether when it concerns evolution, especially evolution applied to human beings. This is "Darwin's dangerous idea" (Dennett, 1995). The opposition to evolution, especially of humans, is not only due to interpretations common among followers of religions, but is found in academia, e.g., among sociologists, cultural anthropologists, and educators. The arguments contain commonly repeated errors. Examples next:
Describe an example from Lorenz'stories of Jackaws in Altenberg, Austria, of how an instinctive reaction can override a learned preference.
One example is that Jackdaws naturally want to fly after the fastest moving object in front of them, while Jock has been raised to follow his owner while he is walking or biking. Lorenz says that Jock sometimes instinctively would follow after someone that passed by Lorenz while biking or walking, then would realize his mistake and fall back behind Lorenz as he has been raised / taught to do.
What is the major adaptive behavior of meerkats for avoiding predators (as shown in the video "Meerkats United"? (3 points)
One meerkat always acts as a sentinel, going to a high place and scanning for predators. When it sees a predator that may attack, it's warning call makes all the meerkats run to their burrow for safety (where the sentinel also runs).
4. How are naked mole rats similar to the Hymenoptera (social insects) in a way that leads sociobiologists to predict altruistic behavior in these mammals? (p 97-98)
One queen, several male consorts. Workers are siblings or half siblings; inbreeding increases genetic relatedness. • The predictions of extreme altruistic behavior have been verified.
4. What are the causes you can discern, or have learned about, for the extreme environmentalism in America? (It has been more extreme in America than in Europe.) P 221
Opposition to attitudes in European aristocratic society with its elitism based on inheritance. [Discussed in class in September] • In America, ideals of democracy include the belief that "all are equal", which should mean "equal opportunity under the law", but is often taken to mean equal at birth, with everything possible to everyone who has the will and can find the opportunity. • This was applied to the education system, with good outcomes despite the inaccuracy of the beliefs
Use optimal foraging to explain why crabs choose to feed on intermediate-size mussels instead of the more meaty large ones. (3 points)
Optimal foraging theory makes the assumption that animals make choices that will maximize their net energy gain and in doing so take in more energy than they expend feeding. Bigger mussels take longer to open and so the crabs may "spend" more energy to reach the food they contain. This can be expressed as an optimality model E/T.
Polygynandry, as in the Dunnock
Polygynandry is a mating system in which both males and females have multiple mating partners during a breeding season.
Distinguish between primary and secondary defense strategies of prey animals. Give an example of each. (4 points)
Primary strategies decrease the likelihood of being detected and attacked. • Example: Camouflage and other hiding strategies • Example: Group foraging Secondary strategies decrease the likelihood of a predator's success after initiating an attack • Example: high speed of flight • Example: playing dead/ tonic immobility
8. From the appendix, ch 7, Q3: What misunderstanding(s) are embodied in the following statement from a sociology textbook published in 1999. "In our view, the theory that there is actually a biological basis for reciprocity [among humans] remains unproven; general self-interest and an ability to see beyond the short term may be all that is required to generate such ... behavior."
Quote from a sociology textbook: "In our view, the theory that there is actually a biological basis for reciprocity [among humans] remains unproven; general self-interest and an ability to see beyond the short term may be all that is required to generate such ... behavior" (Wallace and Wolf, 1999: Contemporary Sociological Theory, 5th edition, p 391) Confusion of proximate and ultimate causes What misunderstanding(s) are embodied in this statement?
6. (Not discussed in Alcock's chapter 7) What attributes determine preferences shown by females in choosing males? How would you expect such preferences to differ from those of males for females?
Remember the discussion of this in the book by Scott**What attributes determine preferences shown by females in choosing males? • How would you expect such preferences to differ from those of males for females? Females have different concerns (as discussed in previous classes), so "maximum reproductive potential" has a different meaning. Note differences in age preferences: Mean age difference at marriage is 3 years, with males being 3-yr older.
What has DNA analysis revealed about female sandpipers who desert a first clutch of eggs and find another mate with whom she lays more eggs?
Sandpipers: • DNA analysis: The second clutch of eggs may have been fathered by the first mate and not the second. • In such a case, she has stored sperm from the first mate, and delayed its use! - She has been able to make a covert choice. [Cf. Kangaroo, with a back-up fetus]
Give an example of an artificial selection experiment that has shown strong genetic influences on behavior. How has this been supported by studies of humans?
Selective breeding for particular behavioral traits in laboratory studies - Crickets (loud singing group, silent group) - Rats (maze-bright, maze-dull strains) Human twin studies: Studies of concordance rates • Examples: concordance rates for monozygotic twins: - Schizophrenia, 40-60% concordance in monozygotic twins compared with 10-20% in heterozygotic - Similar for bipolar disorder—but the claims in the literature vary widely. - Type 1 diabetes, 67% concordance in one study. As low as 30% when studied at only one (early) time point, but this gets progressively higher when twins are studied over many years.
How does the female jackdaw respond to a male's attention in the way that signals an engagement? This happens 12 months before sexual maturity and actual mating. (2 points)
She assumes the ritual mating invitation posture in front of the male (without any actual mating at that time).
10. See Appendix, ch 5: Q2. Suppose someone said to you that given a choice between a cultural explanation for human behavior and a sociobiological one, you ought to give precedence to the cultural explanation because our behavior is so obviously shaped by the culture in which we live. How would you respond (if you were a sociobiologist)?
Should one type of explanation be given preference in explaining human behavior? It is a nature-nurture issue. As always, both are involved, so the scientist must keep an open mind about investigating the contributions of both.
E. O. Wilson
Sociobiology: The New Synthesis, manifesto against it because scholars at the time believed in Marxism and favored nurture over nature; argues that natural selection works not only on individuals but also on groups (as sociobiology develops/reviewed by Alcock - group selection rarely emphasized)
15. Find other examples of the biasing of the sex of offspring.
Soon after Komdeur's first report, a related finding appeared on tawny owls: Does variation of sex ratio enhance reproductive success of offspring in tawny owls (Strix aluco)? Bridget M. Appleby, Steve J. Petty, Jeremy K. Blakey, Paul Rainey and David W. MacDonald (1997) Proc R Soc London B, 264, 1111-1116 Tawny owls laid female-biased clutches on territories with more abundant prey (field voles) in June, the month that chicks fledge. Eggs were laid in March. From their introduction: "In this paper we present the results of a study on sex ratios from a population of tawny owls, which indicate that parent owls produce more female chicks on territories with higher numbers of their major prey, field voles Microtus agrestis, at the time the young are fledging.. This is adaptive because females but not males appear to enjoy a subsequent reproductive advantage from being reared under good food conditions."Tawny owls: The sex-biasing decision by the owls must be made in March, based on a prediction of what the prey density will be in June! Sex-biasing phenomena were known earlier, but benefits for genetic fitness were not investigated before Komdeur's studies of Seychelles warblers and this study of tawny owls
11. What are "eusperm" and "parasperm" and their functions?
Sperm competition and cryptic female choice profoundly affect sperm morphology, producing diversity within both species and individuals. One type of within-individual sperm variation is sperm heteromorphism, in which each male produces two or more distinct types of sperm simultaneously, only one of which is typically fertile (the 'eusperm'). The adaptive significance of nonfertile 'parasperm' types is poorly understood, although numerous sperm-heteromorphic species are known from many disparate taxa. This paper examines in detail two female-centered hypotheses for the evolution and maintenance of this unconventional sperm production strategy. First, we use game theoretical models to establish that parasperm may function to protect eusperm from female-generated spermicide, and to elucidate the predictions of this idea. Second, we expand on the relatively undeveloped idea that parasperm are used by females as a criterion for cryptic female choice, and discuss the predictions generated by this idea compared to other hypotheses proposed to explain sperm heteromorphism. We critically evaluate both hypotheses, suggest ways in which they could be tested, and propose taxa in which they could be important.
2. Formulate two statements summarizing a sociobiological finding, in the following manner: For one of them, make it sound like people ought to behave in a certain way. Then re-state the finding in a more objective way. P 193
Statement: "It is natural to being male for men to want to have power and dominance over others, including women." This sounds like approval or justification. Re-statement: Men, more than women, have a tendency, on average, to strive for positions of power and dominance. Natural vs Good (Alcock, p 193-194) • "...the improved understanding of something derived from the scientific process is analytical, not approving or disapproving, not accepting or rejecting on moral grounds." Evolved traits "have helped keep certain genes in the gene pool, not because it was good for the individual, good for the group, or good for the species as a whole, but because possession of these traits happened to be correlated with success in gene propagation." • "No moral lessons can be drawn from the unfeeling, blind process of natural selection."
7. Humans everywhere have a strong tendency to stay and act within groups, and these groups may compete with each other, sometimes violently. Try to specify a list of evolutionary fitness benefits of "groupism" feelings. p 143-147
Staying with a group: an innate preference Examples of fitness benefits of groupism feelings: • Higher probability of finding a mate • Higher probability of rescue and survival • Higher probability of better defense against predators • Higher probability of better defense against hostile human groups • Advantages in food acquisition: gathering, hunting, with sharing and specialization • Help in child rearing and education • Advantages in learning from older, more experienced group members
8. Is it true that "all rape is an exercise in power" and is not about sexual desires?
Susan Brownmiller (1975), Against Our Will. Her views became very widespread, and have been taught to students at many universities, in propaganda on the "myths about rape." Not true. Also note that it is widespread among animals, although certainly not in all species. What are some of the actual findings of studies that have collected real data? See especially p 210-211, and Fig 9.5: "Age distribution of rape victims differs significantly from that of homicide victims" Peak age for rape victims was 22-23 Peak age for murder victims was 32-33, and the distribution falls off with age less steeply
How does the body react to a novel stimulus? Describe two physiological measures. Then describe a behavioral response. (4 points)
Sympathetic nervous system arousal. One measure: changes, usually an increase, in heart rate Another: galvanic skin response Another: vasoconstriction in the limbs, as in the fingers (with decreased finger volume) Another: alteration in the regular breathing rhythm
11. See Appendix, ch 8, Q2: "If men and women differ in how much they invest in parental care, it is strictly because of the nature of societal influences they experienced when young, which shaped their view of appropriate sex roles?" How could you test this hypothesis?
Testing a cultural determinism hypothesis How could you test this hypothesis? (Are all malefemale differences in parental care learned?) Cross-culture studies. Why is it that nearly all cultures are similar in this? Twin studies: Are variations in parental care genetically influenced? Effects of deliberate attempts by caregivers to influence children...
Why did a group of scientists write a "manifesto"against a large new book by Edward O. Wilson entitled Sociobiology: The New Synthesis? What were their claims, and what was the nature of the intense political activity on campuses in the mid-1970s?
The New Synthesis, manifesto against it because scholars at the time believed in Marxism and favored nurture over nature; argues that natural selection works not only on individuals but also on groups (as sociobiology develops/reviewed by Alcock - group selection rarely emphasized) Their claims 1. Wilson's theory could be used to justify existing social inequalities. 2. It was founded on the kind of false science that had been used to support the eugenics policies of the Nazi party. The intense political activity of the mid-1970s • The anti-war movement, opposed to the war in Vietnam, included much intense political activity on campuses, much of it supported by left-leaning professors.
6. Why should it matter to European wood ant workers whether their mother mates with one male or with several? (p 102)
The ant workers behave very differently. This presents us with a puzzle. How can the puzzle be solved? It involves gene counting Why should it matter to European wood ant workers whether their mother mates with one male or with several? p 102 • Because the gene calculations are very different if she mates with one male or more than one. - One male: The female workers share up to 75 % of genes with sisters, and only 25% with brothers. - Two males: Workers who are half-sisters share only 25% of genes, the same as with brothers. • Somehow the workers know, because proportional investment in females by workers does depend on the mother's mating status. Sisters get more care only if mother is monogamous.* • "No one would ever have looked for such a thing if they had not been educated by Hamilton and Williams." (Key papers: W.D. Hamilton, 1964; G.C. Williams, 1966.) W
How has evidence been obtained that the stars are used to guide long-distance migrations of birds? Describe a specific experiment. (3 points)
The birds were placed inside a planetarium shortly before the time when they would begin migration. Initial flight directions were recorded. These directions were found to depend on the positions of the stars. The overhead sky could be rotated so it did not correspond to the actual position, with the same results, indicating that the earth's magnetic field was not determining the initial flight directions.
Leyhausen, P.
The ethology of various species of cats
9. From the appendix, ch 7, Q2 (quoting Alcock): Languages vary greatly among human societies. If someone claims that this fact clearly demonstrates the greater importance of culture than biology in the control of human behavior, what would a sociobiologist say in response?
The important issue is language vs no language, not the details of a particular language. Humans are born with an innate ability to learn any language.
How is the motivation for tool activities different from the motivation for other activities? (3 points)
The level of motivation (ASP) has an endogenous increase that occurs at a much faster rate, [since these multipurpose movements are used more often than other activities].
12. According to a study published in 2006, this kind of love is one of two related but distinct inherited drives (FAPs). [Reference: Gonzaga, G. C., Turner, R. A., Keltner, D., Campos, B., & Altemus, M. (2006). Romantic love and sexual desire in close relationships. Emotion, 6: 163-179.] How can these be distinguished experimentally? Are there really only two drives associated with what is called"love"?
The two drives: 1) Romantic love, related to commitment • Expressive actions are correlated with oxytocin release 2) Sexual desire, related to reproduction Abstract (Support for two distinct drives/FAPs) Drawing on recent claims in the study of relationships, attachment, and emotion, the authors hypothesized that romantic love serves a commitment-related function and sexual desire a reproduction-related function. Consistent with these claims: • In Study 1, brief experiences of romantic love and sexual desire observed in a 3-min interaction between romantic partners were related to distinct feeling states, distinct nonverbal displays, and commitment-related and reproductive-related relationship outcomes, respectively. • In Study 2, the nonverbal display of romantic love was related to the release of oxytocin. Discussion focuses on the place of romantic love and sexual desire in the literature on emotion. If you check the literature more broadly to include psychological studies and reports by counselors and by psychiatrists, you will find claims of a much greater number of distinct feelings/motivations subsumed under the term "love."
1. What big change in animal behavior research occurred after about 1970? (pp 94-95)
There was a shift in emphasis from proximate causation to ultimate causation, i.e., adaptive significance. An exception was in the behavioral studies by scientists focused on brain mechanisms, including neuroethologists and others working on brainbehavior relationships.
6. Why do humans engage in behaviors that seem to reduce their fitness?
They may not really reduce fitness; they are Darwinian puzzles. Sociobiologists attempt to solve them. - Keep in mind that behaviors that evolved to increase fitness may no longer do so in greatly altered environments. • Examples: - Pet love (previously discussed) - Alcoholism (A preference may have evolved because alcohol was present in ripe fruits that were healthy to eat.) - Acts of altruism: studied by Robert Trivers (1985) and by Richard Alexander (1987): reciprocal altruism, and the value of a reputation for charitability - Use of spices? (See next question) - Voluntary reductions in family size; the demographic transition (See question 7)
2. What would the long-range evolutionary outcome be if, at a given time, most people had "blank slate" brains at birth? (p 153)
They would have to learn everything with no innate biases, so they could be fed information that would allow them to be taken advantage of - exploited - by variants who had more targeted brains. With genetic variation, the totally blank-slate individuals would decrease and disappear. Noam Chomsky: "The blank slate brain is a dictator's dream."
In discussions of evolution, one hears the terms "natural selection" and "sexual selection." Contrast these terms. Give examples of a behaviorally related trait that evolved by natural selection and one that evolved by sexual selection.
Traits evolve due to natural selection because they increase and individual's survival until reproduction. Traits evolve due to sexual selection because they make an individual more attractive to a potential mate (thus benefitting reproduction). Example of trait that evolved due to sexual selection: long/elaborate/decorative tail feathers of the male Bird of Paradise. More long and elaborate tail feathers make the male more attractive to females. They don't serve any survival purpose (not natural selection). But since they have few natural predators and the tail doesn't affect foraging, it was able to evolve through sexual selection. Trait evolved by natural selection: alarm calls of various monkeys, ground squirrels and other species; benefit an individual's survival for reproduction.
Why do honeybees dance in the hive, communicating the location of nectar and pollen sources? Describe one ultimate and two proximate hypotheses.
Ultimate hypothesis: • The cause of the dance is to increase the amount of nectar brought to the hive to feed the queen, the larvae and the others, promoting reproduction. Proximate hypotheses: • Worker bees can detect their flying directions and compute the directions to and from the source of nectar. • The bees use the position of the sun for directions.
3. In 1964, William D. Hamilton published a very influential paper that included an analysis of the altruistic behavior of sterile workers in colonies of social insects. What knowledge that had been unavailable to Charles Darwin did Hamilton apply to this problem? (p 96)
Unlike Darwin, Hamilton had knowledge of genes: He focused on the genetic consequences of extreme altruism. He pointed out that, in a colony of social insects, males are haploid, but females are diploid. If a queen's eggs are all fertilized by one male, then sister offspring share 50% of the mother's genes, 100% of the father's, hence 75% with each other. This should promote altruistic behavior of female workers toward sisters who are future queens. It increases chances of reproduction of their own genes• What are the alternatives to Hamilton's theoretical analysis in explaining the evolution of a sterile worker class in social insects? See the article posted online: "The evolution of eusociality" by Nowak MA, Tarnita CE & Wilson EO (2010), Nature 466: 1057-1062. The authors present an alternative to the "inclusive fitness" theory, but not to natural selection.A few of the arguments against relying on inclusive fitness theory to explain the evolution of eusociality: • Eusociality has evolved in species without haploiddiploid reproduction. • In many haploid-diploid species, eusociality has not evolved. • The predictions of inclusive fitness theory are very complicated and difficult to work out. • Eusociality can be accounted for using only adaptive natural selection, without using inclusive fitness theory. Eusociality, the highest level of organization of animal sociality, is defined by the following characteristics: cooperative brood care (including brood care of offspring from other individuals), overlapping generations within a colony of adults, and a division of labor into reproductive and non-reproductive groups. ...
Describe the very different ways in which an animal can maximize its reproductive output.
Very different between males and females: - It is easiest for the male to increase number of offspring. - For the female, with limited egg production, it is better to try to maximize quality of offspring (including the choice of a father with "good genes" and with good resources to contribute). Additional factor: reproductive investment, which is quite variable as just described.
11. See Appendix, ch 5: Q1, first question. (The other questions are also interesting.) In the study of EPCs by birds, are there gender biases in the topics of study? Are male and females scientists different in their approaches and biases? (See Alcock's wordings of several questions on p 227.)
Why did earlier studies of EPCs in birds focus only on males? (Did they?) Most of the earlier studies were done by male scientists. Was it just a case of gender bias, and is such bias built into selectionist theory? (There were fewer female scientists then.) Can you suggest a sociobiological hypothesis in which male and female scientists are proposed to have different perspectives and interests on matters of animal reproduction? As persons, not scientists, they do have different interests. As scientists, they are obligated to use as many perspectives as possible.
Why is variation within species so important for evolution?
Without diversity, when environmental changes occur, a species may not be able to adapt successfully over multiple generations. • When a species becomes endangered, the number of individuals may become small so the variation may not be sufficient for any of them to survive. • This could lead to extinction of the species.
What was the thesis of Wynne-Edwards in his 1962 book, which was forcefully countered in 1966 by George C. Williams? Describe Williams' counter thesis, which is a key for understanding modern sociobiology (since 1975).
Wynne-Edwards: Animal Dispersion in Relation to Social Behavior - 1962, interpreted almost every aspect of social behavior to be altruistic self-sacrifice that advances the welfare of the species George C. Williams: Adaptation and Natural Selection - 1966, evolved adaptations are extremely unlikely to promote long-term advance of the species at the expense of individual reproduction
5. Give a sociobiological interpretation of the finding that Yomybato men tend to prefer females with a figure that is heavier and with a larger waist-to-hip ratio than preferred by most men in more advanced cultures. p 141-142
Yomybato men's preferences: • Alcock's suggestion (somewhat fuzzy, & not yet fully tested): p 141-142: - Obesity was all but impossible in pre-colonial Amerindian groups, and being underweight was probably more common. - If a woman was slightly overweight, there was a greater probability of her being fertile. • This suggestion should apply to other groups. • If the findings are due to isolation from modern cultural influences, it should be similar for other groups that have been isolated from modern societies. • We need more information about the advantages of extra body weight for withstanding diseases, etc. • Also note: One exception does not disprove the general finding.
"One sometimes reads that sociobiologists are attempting to make the case that certain differences between individuals or races are genetic in origin. Thus, the supposed goal of the sociobiologist is to establish that the criminal differs hereditarily from the noncriminal or that the average IQ score differs among racial groups because of genetic differences between individuals or populations. How would a sociobiologist respond to this claim?"
a) Both criminality and intelligence involve complex behaviors that involve many genes and large influences of environment. b) In the case of criminality, it has been claimed that a chromosomal anomaly (XYY, Klinefelter's Syndrome) results in greater probability of violence and criminality. However, recent studies have attributed such results to differences in socioeconomic level rather than genetics. c) In the case of intelligence: • First an important caveat: The measures that have been done show very small but statistically significant differences between populations, but the variations among individuals in each group greatly exceed those population differences. • Secondly, a critique of the idea of "intelligence" as defined by any specific test: Environmental and cultural effects have been demonstrated repeatedly. In addition, multiple intelligences have been supported by strong evidence. (For some of these there are definite genetic influences but there are always environmental influences as well.) The existence of a measureable "general intelligence" independent of environmental and cultural effects has been questioned by scientists many times.
Definitions: a) Population b) Deme c) Species d) Society e) Social homeostasis f) The multiplier effect g) The evolutionary pacemaker h) Adaptive demography i) Behavioral scaling j) Compromises in social evolution k) Ultimate vs. proximate causation
a) Population • A set of organisms belonging to the same species and occupying a clearly delimited area at the same time. • The population is bounded by a zone of sharply reduced gene flow. (Compare with "society" below.) b) Deme The special population used by model builders, defined as the smallest local set of organisms within which interbreeding occurs freely. c) Species a population or set of populations within which the individuals are capable of freely interbreeding under natural conditions. d) Society The society is bounded by a zone of sharply reduced communication. e) Social homeostasis regulation of colony subgroup sizes, caste proportions, etc. f) The multiplier effect - Occurs when a small evolutionary change in individual behavior results in major effects on social behavior patterns. - Example: baboons, hamadryas vs. olive: Hamadryas males "possess" particular females long-term, whereas Olive males do so only during estrus periods of females. Result: great differences in social structure. g) The evolutionary pacemaker - Evolutionary changes in behavior generally occur before changes in body structures involved in the behavior. Wolfgang Wicker has found good evidence of this in fishes & birds. Example: the puffer fishes What starts as adaptive anti-predator behavior has evolved into structural properties of some species within the same group of fishes. h) Adaptive demography Relative proportions of individuals of different ages and sizes can be influenced by selection in favor of groups of certain ages vs the individual. i) Behavioral scaling With no difference in genetics, behaviors can change as a function of conditions. E.g., increases in population density can drastically alter aggression and territoriality. j) Compromises in social evolution Evolution leads to compromises in social evolution, as adaptations at one level may not be adaptations at another level (e.g., individual, family, population levels). Example: the evolution of altruistic behavior in groups—resulting in behavior that may not be adaptive for an individual but is for the group. k) Ultimate vs. proximate causation A proximate cause is immediately responsible for causing something observed, and ultimate cause is considered the underlying or real cause. Separating these two meanings leads to better understanding of events.
William Kimler
also misguidedly critiqued sociobiology - failed to recognize that proximate motivational states are distinct from ultimate results (in reality, proximate and ultimate hypotheses are different but complementary)
Alcock
claims: human behavior should differ greatly and arbitrarily from society to society, "genetically determined" behavior doesn't exist
Derek Bickerton and Michael Rose
misconceptions about sociobiology, critiqued sociobiology based on the belief that fitness is about conscious intent (wrong because fitness is NOT about conscious intent)
Robert Ardrey
misused the comparative method; claimed that humans have territorial instincts because of widespread occurrence of territoriality in non-human animals, wrong because territoriality not universal in humans and varies widely from culture to culture
Flying in birds, like various locomotor gaits in mammals, is innate. Describe how, although this is true, Jackdaws (as well as other birds) learn many details of flying from their experiences. What is Lorenz' argument for this?
older birds, not young birds, are faster and acrobatic; only experienced birds engage in playing with the wind
Stephen J. Gould
one of the critics of sociobiology, claimed that evolutionary speculation can only help if it teaches us something we don't already know (like that a gene is linked to genocide); bad claim because sociobiologists look at ultimate mechanism but he critiqued them based on proximate ones; also said that human brain has lots of capabilities but not predisposed to any (in regards to cultural development)
10. What is meant by "cryptic female choice" in sociobiology? Would you expect such phenomena to be found in mammals? Humans? (p 116) It is found also in plants! Remember from Scott: the female spotted sandpiper; the behavior of male and female dunnocks; sperm removal by some male insects.
p 116 (alcock) Phenomena of cryptic female choice Alcock introduces this with an example from botany (p. 116-118), describing a female flower's response to pollen of various origins. "...as soon as researchers began to employ gene thinking, they started finding fascinating things about plant reproduction that previous workers had overlooked." Also discovered: the equivalent of sperm competition by chemicals released from pollen that landed on nearby parts of the style surface.• Remember the female spotted sandpiper: She leaves her first mate with her first clutch of eggs, and flies off to establish a nest and 2nd clutch with another male. • However, she may inseminate the second clutch of eggs with stored sperm from the first male!• "Last sperm precedence": a strategy that has evolved in females of many species - The ability of female birds to store sperm in tubules near the junction of vagina and uterus: they fill up from the back, so the last sperm in are the first to be released at the time of fertilization. • How have males evolved to counter these cryptic abilities of females? - The male dunnock can increase the chances of successful fertilization by his sperm by two behaviors: 1. Frequent copulation, enhanced when he notices his mate in the vicinity of another male 2. Pecking of the female's cloaca prior to copulation contractions that cause sperm excretion - The female can choose whether to allow this behavior, normally conducted as a ritual.Bed bugs are an example of insects, particularly beetles, that practice a violent insertion of sperm into the body cavity of females without using the genital tract. Some females have evolved specialized body parts (thicker outer coverings) to deal with this so there is less trauma to them.Traumatic insemination is most widely practiced among heteropterans (the "typical bugs"), but the phenomenon has also been observed across a variety of other invertebrate taxa.
4. Attributes that determine young men's attraction to young women (on the average) have shown considerable consistency, even across cultures. ("Beauty" is not a myth or a politically determined creation, as claimed by Naomi Wolf.) What is the major, general signal value of these attributes, fitting the expectations of sociobiologists? p 137-139
p 137-139 See next slide, and Table 7.1 in Alcock. Note that what is fashionable does not always match what men actually prefer in a mate. Only the latter is of great interest to sociobiologists. Note also that in poorer societies, higher BMI (body mass index) may indicate greater wealth and therefore be attractive. See Table 7.1 in Alcock (p 138): Some attributes in women that men find attractive and their probably signal value as indicators of high reproductive potential: - The attributes listed indicate health, fertility, sexual maturity and youth. - Together, these are indicators of "lifetime reproductive potential". - Keep in mind that there is always a range, and there are always exceptions to the general rule. Sociobiological hypotheses are not about "always" and are not disproved by "sometimes".There is some variability in measures of the relative importance of different factors, e.g, the Body Mass Index and the waist-to-hip ratio.The authors found that the BMI was a much better predictor than the waist-to-hip ratio. Other studies have not shown such an extreme difference. In fact, the ratio has been often been reported to be more important. See figure 7.1. Both measures are important indicators.
The evolution of long tail extensions in male swordtail fish occurred because of a process known as ______________ (1 point).
sexual selection
Peter Churcher
study of hunting by house cats in England, their hunting plays significant role in population of small animals
Jane Goodall -
study of wild chimpanzees (mentor = Louis Leakey)
1. Give three examples of the misuse of scientific findings or claims in service of political goals. At least one of these examples should concern sociobiology or Darwinian theory. P 189-192
• A "eugenics" argument: Nazi claim that racism, and even genocide, was based on genetics • 19th century "social Darwinism": used to justify dominance and superiority of the rich • The claim that infidelity is natural, therefore understandable, therefore, justifiable. (See Q#7) • Similarly, claims justifying the subjugation of women
3. Conditional strategies are common in humans. Give an example of a conditional strategy in an insect, showing that insect behavior is not always rigidly preprogrammed. (p 156-159)
• A Rove beetle in Costa Rica, L. versicolor is a dung beetle that feeds on flies. • Large males are territorial, with larger jaws. • Smaller males mimic female behavior and are courted by the larger males. While being courted, they can catch flies and mate with females. • The same males change to male behavior in different situations.Conditional strategies Be sure to note that individuals following one or another mating strategy are probably not different genetically. The underlying genes could be the same, but could code for the development of conditional strategies.
What is a lek? How can a male in a lek who never succeeds in mating with a female nevertheless "benefit" by his participation?
• A lek is a congregation of males - in a lek many males come to one area where females come to view them and choose one of them. It's a timesaving and efficient way for females to find a mate in a limited window of time. More females come to larger leks. • Hot Spot Model - males go somewhere that is in females line of travel (females likely to come by) • Hot Shot Model - males congregate around a high-quality male where lots of females will come • Kin Selection Model - many males in a lek genetically related. Even if a male doesn't mate, he contributes to the lek by making it bigger and more attractive to females, and he still benefits from his kin passing on genes • These models are not mutually exclusive
7. The use of spices in cooking seems at first to be a human luxury with no particular adaptive value, and thus their widespread use, and the great value placed on spices in human history, presented a Darwinian puzzle. What adaptive value of spices has been supported by data? (p 177-179)
• Anti-microbial properties. Hence, used more in hot climates. See p 179 figures - Spices that inhibit 100% of bacteria in tests: garlic, onion, allspice, oregano. - Eleven other spices inhibited 75% or more of the bacteria • Also note: East African practices by Maasai and Batemi. They use plant additives in milk that lower cholesterol (saponins, phenolics)
What ecological pressure makes solitary foraging more likely?
• Chronic food shortages make solitary, anti-social behavior more likely (e.g., the moose)
How is the comparative method used by adaptationists (sociobiologists) to test hypotheses about adaptive social behavior?
• Comparative Methods = animals of different species should show the same type of adaptive social behavior if (1) they are faced with sufficiently similar social selective pressures, and (2) they have a similar social organization • Means that you can test a hypothesis on multiple species if these conditions are met • Geese have similar social structure to humans/meet these conditions, so its reasonable to hypothesize about humans based on Lorenz's work with geese
Instincts are sometimes said to be more strongly controlled by genes than is learned behavior. Do you agree or disagree, and why? In your answer, discuss your view of how genes influence the development of the physiological systems necessary for activating an instinct (the innate response to a particular cue) or for controlling a learned behavior (which requires the use of information acquired from experience to modify an individual's behavior)."
• Complex behavior is influenced by multiple genes, and is never free of environmental influences • On the motor side, many instincts have fixed motor patterns that depend on inherited CNS mechanisms. • Learning depends on inherited brain mechanisms as well. What is learned, of course, varies with the learning experience. • In the case of a learned influence on the stimuli that elicit an instinctive behavior, the genetic control cannot be said to be more important than the learned control. • Thus, whether genes are more strongly in control of a behavior depends on which aspect of the behavior you are focused on. The question is only rarely meaningful for an entire behavior pattern.
What is meant by serial polyandry in sandpipers? Explain the female sandpiper's ability to exercise cryptic choice.
• Female and male mate, female leaves eggs with male, then she goes and mates with someone else and she takes care of those eggs • DNA shows that sometimes the second clutch was fathered by the first male and not the second - she stored sperm from the first male and makes choice depending on quality of the second male - female cryptic choice
Discuss sexual cannibalism in the praying mantis with regard to variability and with regard to interests of male and female.
• Females don't always eat male - well-fed female produces heavier eggs (more likely to survive), so she'll only eat the male if she's hungry • Males try to avoid getting eaten because it's less advantageous for them because they can mate again
Define "fitness" as the term is used by sociobiologists. What are fitness costs and fitness benefits? Give examples
• Fitness = number of an individual's genes passed to surviving offspring • Fitness costs = reduce probability of gene survival • Fitness benefits = increase probability of gene survival Example: Think of possible fitness benefits & costs to a female bird when she engages in extra-pair copulations (EPCs). Are these the same for a male bird? Then think about how you could gather information to test these possibilities. (This is what sociobiologists do.)
In more recent studies, how representative of songbirds is the red-winged blackbird? Do the benefits of EPCs always outweigh the costs for the female? And for the male?
• For females of many species, the costs often outweigh the benefits. The costs: reduced parental care by the male. • For males, benefits may be more likely to outweigh costs. • A number of studies have cast doubt on the generality of any broad conclusions of the study of redwinged blackbirds by Elizabeth Gray. In 10 of the 14 species reviewed, EPCs benefitted only males doing it, not females.
The relevant principles of population biology
• Formula for rate of change in population size: dN/dt = rN [(K-N)/K] Note the variable "K", the carrying capacity of the environment. If N becomes greater than K, the population's rate of change becomes negative; if it is below K, the population grows at a rate described by the formula. • r selection: found in a species capable of very rapid growth in numbers by a high birth rate. This allows opportunistic proliferation during short periods of favorable conditions. Usually in such species there is poor survival beyond the earliest periods of life. • K selection: found in species with more stable numbers, often close to the carrying capacity of the environment. There is slower growth of a population because of few births per female and a more prolonged period of development. Density dependent behavior, and population cycles (true cycles vs. "intercompensation", when population density shifts from one equilibrium number to another with a change in the environment) • Life tables: numbers of individuals plotted according to age ranges. In this figure, Wilson seems to be showing that some human groups—e.g. in India—are closer to r selection than to K selection.
Give two strong reasons why foraging in a group of herbivores may be better for an animal (like a bird) than foraging alone. (4 points)
• Greater likelihood of finding food (with more eyes looking) • Greater likelihood of seeing predators; overall vigilance more continuous and widespread • Less likelihood of being the one attacked by a predator [the dilution effect] • Confusion of a predator (faced by large numbers of escaping animals)
Eibl-Eibesfeldt extended the field of ethology to humans. In his studies of humans, what were his two major approaches and his major findings? (4 points)
• He filmed a variety of emotional expressions and social gestures in children born deaf and blind, and found them to be very similar to those of unimpaired children. • He filmed emotional expressions and gestures in people of various tribal people that had been isolated from contact with the outside world. He did this without their realizing they were being filmed. The results showed expressions similar to those of people in in the civilized world and to those of the first study.
Why are there so many different mating strategies?
• In different species males and females have different costs and needs associated with parenthood. Sometimes two parents are necessary to raise an offspring, sometimes one parent can be less involved, etc. Mating = conflict resulting in a compromise in the interests of one of both parents.
What could cause a non-adaptive change in the evolution of social behavior?
• Incidental effects of pleiotropy (multiple effects of the same gene) - One of the hypotheses about pet love in humans - Why has the tail bud persisted in the human embryo? Loss of the gene may cause maladaptive effects if the gene has pleiotropic effects • Degenerative effects of genetic drift - Can occur most easily in small populations - Hypothesis about the deficient immune system of the modern cheetah, a species which is believed to have gone through a population bottleneck about 10,000 years ago Genetic Drift= variation in the relative frequency of different genotypes in a small population, owing to the chance disappearance of particular genes as individuals die or do
Is it true that "No genes for human behavior have been found" ?
• Is the absence of evidence really evidence of absence of noninvolvement of genes in social development? - Specific genes are being found, but they are not really "for" a behavioral trait, they code for proteins. - Social behavior is always influenced by multiple genes. Current research on genes and social behavior: a few examples Autism ADHD
11. Is the phenomenon of romantic love--the "falling in love" experience—an invention of medieval court life, as has been repeatedly asserted? Does it occur only in certain cultures? State a sociobiological hypothesis concerning its origins.
• Is the phenomenon of romantic love, the "falling in love" experience, an invention of medieval court life, as has been repeatedly asserted? The idea was invented by people who could not accept the idea of innate motivations in humans • Does it occur only in certain cultures? • State a sociobiological hypothesis concerning its origins.Does it occur only in young people? If it has evolved as a human FAP, it is adaptive in a sociobiological sense. Like many evolved tendencies, it can produce conflicts not only in the society, but within the individual. (And this can cause "cognitive dissonance" which the individual will struggle to resolve in one way or another.)About "falling in love" Consider WHY it must have had to evolve in early human groups. Think of the close bonds acquired in growing up in an extended family, within which there were bad consequences of inbreeding. It was necessary for genetic fitness to have a motivation that could occur in strength after sexual maturity-- strong enough to cause a young person to leave his natal group. Result: Roaming in search of a mate; forming secret liasons, eloping, and all of the other characteristics of the falling-inlove phenomenon (including behaving "stupidly" and irrationally, disregarding long-established habits, etc.) Related to this: the breaking of bonds of parental authority, especially between sons and their fathers.
0. Is rape a "natural" behavior?
• It is practiced only by a small minority of men, hence it is not natural in the usual sense. • In some species, forced copulation is more widespread. • However, it becomes more common in humans under certain conditions, as in wartime conquests. (Thus, it could be considered to be a "conditional strategy"—however abhorrent this may seem.)
What is the difference in meaning of the terms "releaser" and "key stimuli"?
• Key stimuli are the simple stimuli that elicit a fixed motor pattern (i.e., they are part of an FAP). • A releaser is a particular movement or visual property of an animal that has evolved so that it is a key stimulus that causes (releases) an FAP in a conspecific.
What are two of the distinct functions of birdsong? (4 points)
• Males attracting females • Females judging males for purposes of mate selection • Territorial advertisement: usually male-male • In some species it also functions in pair-bonding, with duets sung by a pair.
6. Appendix ch 9, Q2 [Repeated from previous class] Defend sociobiology against the following charge: "Sociobiology predicts that only immoral or amoral actions can evolve. When sociobiologists are confronted with the existence of true altruism and moral behavior, they then change their tune and say that these cases illustrate that human beings are able to resist our evolved impulses. But why would we resist if our actions really have evolved via natural selection?"
• Morality itself has evolved, with proximate as well as ultimate causes. • Sociobiologists have studied adaptive values of altruism and moral behavior, and have found explanations. • We have evolved with multiple proximate systems of the CNS, each for adaptive reasons, but conflict is common among these systems. (We did not evolve to be happy!) - We are capable of learning how to deal with these conflicts.
5. What does adaptationist thinking (by sociobiologists) predict about human marriage and step families? These predictions have been tested and verified. P 200-203
• More conflict within step families (less stability), at least when children are involved. • Greater child abuse by step parents, especially step fathers. See figure p 202, on the frequency of criminal child abuse in families. • More divorce when there is a greater number of step children.
What are major factors that slow evolutionary changes in social behavior?
• Phylogenetic inertia: factors that slow evolutionary changes in social behavior: e.g., - Reduced genetic variation (as in periods of very reduced population size) - Genetic swamping • One subgroup begins to change because of altered environmental conditions, but occasional inter-breeding with another subgroup prevents the less adaptive genes from disappearing. • Food type and distribution influences social behavior, e.g., distributed, predictable food sources make territorial behavior more adaptive. However, if food sources change, a group may not change its habits because of genetic swamping.
Give an example of how in some species different individual males adopt very different mating strategies.
• Scarab beetles: big and with horns or small and without horns, small ones are more agile and are able to sneak past a large male into the female's tunnel he's defending and mate with her before the large male can get out and turn around to attack him • Large toads croak loud to attract females, small toads can't croak as loud, so instead they just hang near a large toad and sneak quick copulations with approaching females
Why did such traumatic insemination evolve?
• Sperm competition: Males that do not mate first and were faced with a sperm plug, blocking the female genital duct, could bypass the blockage and get their sperm closer to the ovaries. • It was also a way to reduce the mechanisms of cryptic female choice: e.g., sperm storage pouches could be bypassed. Female evolutionary responses • Evolution of thickenings on body surface, and behavior to direct the male to these areas • One function of these thickenings: production of immune system defenses against bacteria from the male. This was particularly important if the male ejaculate invaded the bloodstream.Phenomena of cryptic female choice
Give an example of the extreme differences in reproductive investment of males and females of some species.
• Stickleback fish: male does al the nesting and care of the eggs (female jus lays eggs and swims of or even tries to eat them) • Many other species of fish: male departs after fertilizing eggs • Lions: females invest more than two years (gestation plus two years of care), males do comparatively little
What are the misunderstandings of sociobiological thinking we can see in the statements of Derek Bickerton, Michael Rose and William Kimler, quoted by Alcock? (pp 25-27)
• The mistakes of Bickerton and Rose: Fitness is not about conscious intent. • Kimler's mistake: He missed that proximate motivational states are distinct from ultimate results.
What problems often happen when animals are bred exclusively for a single physical trait?
• When animals are bred exclusively for a single trait, e.g. a particular physical trait, it is common for behavioral problems to appear. • Example: collie dogs since 1950-60 have been bred for narrower and narrower skulls to emphasize a needle nose. The result has been "brainless ice picks"
What is runaway selection, and what limits it? Use at least one example in your answer.
•Females find a certain trait attractive in males, through evolution that trait becomes so exaggerated until it's ultimately maladaptive physically/hurts their survival •Limited by interference with ability to escape predators or ability to forage or feed mate
Explain the difference between homeostatic and hedonic motivation. (4 points)
•Homeostatic: Motivation created when a value of something that is homeostatically regulated (temperature, glucose level, etc.) deviates more than a certain amount from a set point. •Hedonic: Motivation to experience the pleasure of a rewarding sensation—which may not lead to any benefit for any necessary physiological regulation.
Describe two phenomena that give evidence for individual recognition among jackdaws of a colony (flock). (3 points)
•Jackdaws know their position in the social hierarchy relative to all the other jackdaws in the colony. •A jackdaw always recognizes its mate, even from a distance.
Describe how an older jackdaw can entice a young one to return home—using two IRMs of a jackdaw. (4 points)
•The older jackdaw flies near and utters the "fly home with me" call [recognized by all jackdaws] •The older jackdaw flies near, within easy sight of the young one, and then flies rapidly away, uttering that call. •The sight of the bird flying away, plus the sound of the call, provide two difficult-to-resist key stimuli that induces the young bird to follow.
How can a "wandering spider" catch its prey without using a web, by a kind of touch sensitivity that does not involve direct contact? How does this spider detect the prey animal and how does it respond? (4 points)
•The tiny hairs covering the spider's body are sensory hairs that respond to tiny air currents created by a nearby flying bug, and the pattern allows localization of the flying bug. •The spider responds by leaping into the air and grabbing the bug.