Genetic Influences on Behavior

( What are 3 Thought Pitfalls/how NOT to think in regards to Behaviour Genetics and evolutionary psychology? )

( 1] Genetic Determinism: is the false idea that genes have an invariant and unavoidable effect that cannot be changed. the idea that genes are destiny. it is simply NOT TRUE that just because our genes influence something, it is unavoidable or natural. for example, the discovery that diabetes has a genetic impact didn't result in medical science just abandoning diabetic patience because "nothing could be done about it." instead, they developed ways to prevent it. 2] Social Darwinism: is the False idea that those at the top of social hierarchy are the "best". I.e., survival of the fittest and the less fit need to go. eugenics movement= destructive. Nazi's against Jews= destructive. 3] Evolution is Purposive:. Defending the status quo: Trait came from evolution - it must be good= not true. There is in fact, no plan in evolutionary theory, there is only adaptation to environmental demands and the natural selection process that results.)

What is the Biological Reaction Range?

( Biological Reaction Range, the Environment, Personality & Intelligence Reaction Range tells us that in intellectual growth, much more is involved: genetic endowment, environmental advantage, personal characteristics and the interaction of these factors. ► Take 2 people who have identical reaction ranges. Don grows up in a deprived environment and Jaclyn, in an enriched environment. Don's environment hinders him from REACHING his potential and therefore, scores a lower IQ than Jaclyn. ► The concept of Reaction Range is how we visualize genetic-environmental interactions. ► Reaction Range for a genetically influenced trait is the range of possibilities- the upper and lower limits- that the genetic code allows. ► Thus, intelligence is not fixed at birth. Instead, an individual inherits a range for potential intelligence that has upper and lower limits. ►And it is environmental effects that will determine where the person falls within these genetically determined boundaries. ►Each of us, therefore, has a range of intellectual potential that is jointly influenced by two factors: 1} our genetic inheritance 2} the opportunities our environment provides for acquiring intellectual skills. ► In conclusion: genetic endowment is believed to create a reaction range within which environment exerts its effects. Enriched environments are expected to allow a person's intelligence to develop to the upper region or his/her reaction range. Whereas, deprived environments may limit intelligence to the lower portion of the range. The Reaction Range may cover as much as 15 to 20 points on the IQ scale.)

What are Dominance Hierarchies?

( Birds and mammals could remember the outcome of a past conflict with another animal and so, instead of having to compete a new fight each time there were resources to allocate and protect, social animals developed Dominance Hierarchies. Once a dominance hierarchy is established, and provided it is unchallenged, members of the group can determine access to resources without unnecessary, energy-expensive, and dangerous aggressive encounters. Hierarchies are established in the initial encounters between animals if the group is being formed or if a new member joins the group. After establishing a dominance hierarchy, primates do not need to rely on aggressive behaviour to maintain their dominate status- it is already established. Example, pecking order. {fight, establish who's the dominant one}. )

Whatever the specific topic, an Evolutionary Psychologist thinks about behaviour in terms of?

( Evolutionary Psychology thinks about behaviour in terms of functions and how those functions contribute to the success and adaptability of the individual. It tries to understand human behavior as a series of adaptive strategies, which are essentially behaviors that help a species survive. Basically, evolutionary psychologists are interested in the origins of human behaviour and believe that our tendencies stem from Darwin's concepts of natural and sexual selection. )

If the Reciprocal Altruism Theory is true, we should see?

( If the Reciprocal Altruism Theory is true, we should see: Then social animals should remember who has helped them in the past and should help those individuals. Furthermore, if theory is true, they should also not offer help to individuals who have failed to reciprocate. Transient members are unlikely to be present to offer assistance at some later date. Does not require relatedness )

What is the current theory of personality?

( The Five Factor Model argues that the human personality has a limited number of dimensions, and these basic dimensions [personality traits] are universal across all humans. Why should we find these traits so consistently in cultures around the world? Because these 5 personality dimensions/traits have helped achieve TWO overriding goals:. 1} Physical Survival. 2} Reproduction of Species. These traits include extraversion and emotional stability [helpful in attaining positions of dominance in mate selection]. Conscientiousness and agreeableness [helpful to group survival, as well as in reproduction and the care of children.] Thus, evolutionary theorists regard basic personality traits as having been sculpted by natural selection pressures until they become part of human nature.)

What are the TWO theories of Altruism?

( There are TWO theories of Altruism. 1} Kin Selection Theory: -this theory argues that altruism developed to increase the survival of relatives. -in showing altruism, one individual may perish, but if this increases the likelihood that genetically related individuals survive, the genes that support altruism will be selected for and spread through more and more members of the species among generations. -kin selection theory offers an explanation of why we are more likely to act altruistically toward genetically related individuals, and why the likelihood of altruism decreases as genetic relatedness decreases. 2} Reciprocal Altruism Theory: -this theory argues that altruism is, in essence, long-term cooperation. -that is, if I help you now, you will reciprocate the favor later. -reciprocity theory offers an explanation of why we also offer assistance to and request from non-kin. )

What kind of studies are used to study the correlation between genetics and personality?

( Twin studies are particularly informative for studying the role of genetic factors because they compare degree of resemblance between two individuals who share virtually all of their genes. ► Need 4 groups:. Identical twins reared together. Identical twins reared apart. Fraternal twins reared together. Fraternal twins reared apart. If identical twins who were reared in different environments, by different adoptive families, are as similar in personality as those reared together, then a powerful argument could be made for the role of genetic factors in contributing to personality. )

What is the theory of Evolution?

( ► A slow change in the genes {and therefore characteristics} of a population as they adapt to environmental demands over time. ► Population: an interbreeding set of individuals. ► Changes occur due to heritable genetic mutations. ► Mutations help to create variation within a population's physical characteristics. This makes evolution possible. )

What is the Evolutionary Personality Theory?

( ► Behaviour Genetics researchers attempt to understand how biological factors contribute to differences between individuals on personality traits. ► An approach called Evolutionary Personality Theory askes an even more basic question: Where did the traits come from in the first place? ► The Evolution Personality Theory suggests that personality comes out of Darwin's concepts of natural and sexual selection. So personality, like other traits, is based in biology. Personality traits can be more or less favorable or adaptive. And this evolves over the long course of human evolution. )

What are the two types of Adaptations?

( ► Broad Adaptations: Some evolved biological mechanisms allow broad adaptations {wide use}, such as the ability to learn a language, repeat behaviours that are awarded, and supress those that are punished, reason logically, and imagine future events. ►Domain-Specific Adaptations: Are designed to solve a particular problem, such as selecting a mate, choosing safe food to eat, avoiding certain environmental hazards {snakes, cliff edges, spiders}, detecting cheating and deception in others, and forming cooperative alliances with other people. Domain-Specific mechanisms suggest that the human mind is not a general, all-purpose problem solver but rather, it is a collection of specialized and somewhat independent modules that evolved over time to handle specific adaptive problems. )

What is a Monogamous mating system?

( ► If both female and male investment is high, then they have a Monogamous mating system. ► Equal parental investment. ► Since parental investment is high among both females and males, both sexes compete for mates, so there is no selection pressure for one sex to become significantly larger than the other. ► Therefore, Monogamous species show little sexual dimorphism in size and strength. Especially in birds [that's why male and female birds look so alike].)

What is Parental Investment?

( ► One difference across species is in Parental Investment. ►Parental Investment refers to the time, effort, energy, and risk associated with caring successfully for each offspring. ►Humans invest a lot in a small number of offspring [k-selected]. ►Mice produce large numbers of offspring and offer little care [r-selected]. )

What is a Polygamous mating system?

( ► Polygamous mating system arises when one sex has a higher parental investment than the other. Unequal contributions towards investment. ►*Polygyny*: Poly=many gyny=females -one male mates with many females. -if females of a species have high parental investment, and male investment is low, Polygyny would take place. -female investment is high, so they will be competed for [male competition drives evolution]. -so, since there aren't very many males, the few that are there have to maximize their fitness by producing many offspring with many females. -leads to larger and stronger males. ► *Polyandry*: Poly=many andry=males -one female mates with many males. -females compete with one another for access to the male. -so, it is female competition that drives evolution. ► *Polygynandry*: Poly=many gyn=females andry=males -many males, many females -promiscuity, in which all members of the group mate with all other members of the group. -reduces competition for a mate/peaceful )

What are some examples of Social Adaptations in Humans as time has evolved?

( ► Remember, Evolutionary Psychology suggests that the essence of human nature is the adaptations that have evolved through natural selection to solve problems specific to the human environment. ► Innate ability to acquire language. -babies are born with an innate ability to acquire any language spoken in the world. Language is central to human thought and communication. ► Humans have developed a strong Responsiveness to human faces. ► We have acquired Group-seeking behavior because humans seem to have a strong need to belong and strongly fear being ostracized. ► Some universal emotions. smiling= positive emotion. )

What was the Minnesota Twin Study? According to the Minnesota Twin Study, what factors were the most important in determining personality?

( ► The Minnesota Twin Study was used to research the correlation between genetics and personality. ► For those twins who were separated and reared apart, the median age at separation was at 2.5 months old- demonstrating little shared experience within the same family environment. ► Through this study, it was found that: -Genetic factors accounted for 39% to 58% of the variation among people in personality trait scores. - Unique experience, such as school experiences, social interactions, and individual learning experiences accounted for: 36-56% of the variation in individual personality traits. -Familial environment: little or no effect. Surprisingly, the degree of resemblance did not differ much whether the twin pair were reared together or apart, showing that general features of the family environment, such as emotional climate and degree of affluence, accounted for little or no variation in any of the personality traits.)

What is Evolutionary Psychology?

( ► The field of Evolutionary Psychology seeks to understand how behavioural abilities and tendencies have evolved over the course of millions of years in response to environmental demands. This is based on the theory of Evolution. ►How are evolutionary mechanisms predisposing people to act the way we do? ►Evolutionary psychologists suggest that the essence of human nature is the adaptations that have evolved through natural selection to solve problems specific to the human environment. Evolutionary Psychology tries to understand human behavior as a series of adaptive strategies, which are essentially behaviors that help a species survive. Basically, evolutionary psychologists are interested in the origins of why we behave they way we do- and they suggest that it is stemmed in Darwin's concepts of natural and sexual selection. )

Despite competition for mates, food, and safe places to sleep, social animals help one another. What are the TWO broad categories of helping?

(Cooperation and Altruism. Cooperation:. one individual helps another and gains some advantage. E.g., cooperating to achieve a goal. able to achieve more when together. finding food, dealing with predators, protecting territory, caring for young. Increases likelihood of survival. Altruism:. occurs when one individual helps another, but in doing so he or she puts themselves at risk. On the surface, altruism may not appear to make evolutionary sense; because, by engaging in altruism, individuals decrease the likelihood that they will survive. )

To what extent are differences in intelligence due to genetic factors? To what extent are differences in intelligence due to environmental factors?

(Heredity, Environment, & Intelligence: ► The question of IQ being determined by genes or environment is a very controversial question. ► IF intelligence was really determined totally by genes than in that case, any two individuals with exactly the same genes would have identical IQs. ► So, the correlation between the test scored of identical twins would be close to +1.00. And, the correlation between fraternal twins- who only share 50% of their genes with each other- would be lower. ►Extending the argument further, the correlation between a parent's test scores and his/her children scores should be about the same as that between siblings, because a child inherits 50% of their genes from each parent. ►In fact, correlations between test scores of identical twins are actually higher than fraternal twins. The correlation for identical twins raised apart is actually nearly as high as that of identical twins reared together, and higher than that for nonidentical twins raised together. ► So, YES- the truth is, the more genes people have in common, the more similar they are in IQ. So, genes DO play a major role in intelligence. ► But, the correlation for identical twins raised together is still higher than the figure for identical twins raised apart and not exactly the same. ► So, this shows that genes are NOT entirely responsible for our intelligence. ►Genotype, therefore, really only accounts for 50% to 70% towards our Intelligence {IQ}. ► Thus, environment, TOO, contributes significantly to intelligence. ► The REAL question should be: "How does heredity AND environment INTERACT to affect intelligence?)

Over the course of several years, what structure of the human body has evolved the most? How has it impacted human behaviour?

(► The greatest pressure was placed on the brain structures involved in the abilities most crucial to the emerging way of life: -attention -memory -language -thought ► These mental abilities became important to survival in an environment that required the ability to learn quickly and solve problems. ► The brain tripled in size, and the most dramatic growth occurred in the FRONTAL lobe- the part of the brain that is set for higher mental processes. ► Thus, evolved changes in behaviour seem to have contributed to the development of the brain, just as the growth of the brain contributed to evolving human behaviour. )

Think back to the 3 Levels of Analysis. Biological, Environmental, and Psychological. How can Behavior Genetics be categorized into these 3 levels?

Although the focus so far has been on genetics and behaviour, all 3 scientific Levels of Analysis- biological, environmental, and psychological- are involved in the context of discovery. ► Biological: -human genome research is unlocking the secrets of our genetic structure and has already dispelled long-held beliefs, such as that concerning the number of genes in the genome. -genes influence the development, structure, and function of the cells by controlling the production of proteins. -genes can be switched on and off, which provide insight on biological structures. ► Environmental: -evolutionary researchers focus on the environmental factors that have fostered behavioural adaptations through natural selection processes. -twin studies {especially twins raised apart} provide insights into genetic factors as well as shared and unshared environmental factors. -research on the manner in which genetic factors influence the learning environments that people select or create through their own behaviour sheds light on gene-environment interactions. -cultural learning can affect the expression of gene-influenced behaviours. ► Psychological: -the psychological products of gene-environment interactions cannot be studied without an understanding of the behaviours and psychological processes of interest. -specific ways in which environment and genetic factors exert their individual and combined effects on behaviour.

As animals evolved larger, more complex brains and more sophisticated mental functions, an important change occurred in competition:

As animals evolved larger, more complex brains and more sophisticated mental functions, an important change occurred in competition: animals acquired the ability to recognize others and to remember past encounters.

What do Women and Men prefer in their mates?

Both Women and Men want: -Mutual attraction -Dependability -Emotionally stable Women want: -Earning -Status -Ambition -3 and 1/2 years older -Symmetrical face (free of parasites, healthy development) -High parental investment Men: -Psychical attractiveness -Good health -Young & Health -Symmetrical face

What is Human nature?

Human nature is the expression of inborn biological tendencies that have evolved through natural selection. Each of us is an evolutionary success story. The vast majority of genes we share in common with all other humans create the "human nature" that makes us like all other people.

If parental investment is unequal, which sex will be more highly competed for? And who will be more picky in selecting a mate?

If parental investment is unequal, there will be more competition for the sex that makes the highest parental investment [usually female]. The sex with the highest investment will be more picky in selecting a mate.

If the Kin Selection Theory is true, we should see?

If the Kin Selection Theory is true, we should see: A Positive relationship between acts of altruism and degree of relatedness. I.e., more altruistic acts toward relatives.

Why has the use of Aggression developed?

May have evolved to: protect one's mate, young, territory, food take/co-opt another's resources gain access to new resources

What to we have to take into account to study the correlation between genetics and personality?

Need to study: Genetic contribution Shared family environment Unique individual experiences

What do our personal adaptations to life result from?

Our personal adaptations to life result from our interactions with immediate and past environments. Theorists propose that as the human brain evolved, it acquired adaptive capacities that enhanced our ability to learn and solve problems. That is, we are predisposed to learn.

Genetic Relatedness percentages for: Parents: Grandparent: Identical Twins: Fraternal Twins:

Parent = 50% Grandparent = 25% Identical Twins = 100% Fraternal Twins = 50%

What do sex differences in parental investment explain?

The two parents may not invest equally in offspring. These sex differences in investment can explain mating systems (Trivers).

Does the environment have a role in how genes determine traits?

Yes, our unique characteristics as individuals arise from the combination of our learning experiences and the environment in which we behave, reflect the interaction between genes and the environment. All of our behaviours reflect the interactions between genes and the environment. Favorable and unfavorable environmental conditions act on genetically determined potential differently. Opportunities provided by the environment influence the expression of genetically based differences.

Besides the development of the brain having an impact on human beaviour, what else was the evolution of behaviour impacted by?

► Evolution of behavior also impacted by culture. ► From an evolution perspective, culture provides important environmental input to evolutionary mechanisms.

What is Natural Selection?

► Heritable characteristics that increase your likelihood of surviving remain in the population and become more common over time. ► You don't die therefore, you pass on more genes than those that did die. "Survival of the fittest." ►Adaptations: the traits that occur due to natural selection.

Is personality heritable?

► The extent to which personality is genetically acquired is a very vague and much debated concept. ► Research has indeed, however, found evidence for specific genetic components of some personality characteristics.

What are Evolutionary Adaptations?

► The products of natural selection are called Adaptations. ► Adaptations allow organisms to meet recurring environmental challenges to their survival, thereby increasing their reproductive ability.