anthrbio 201 midterm 4
grandmothers informing societies
- In some foraging societies, grandmothers spend more time per day foraging for wild plant foods than do mothers of young children or unmarried girls.
poor Nutritional cues... Fetus can "prepare" by
- Increasing metabolic efficiency - Slowing growth of organs - Slowing growth of size
good Nutritional cues... fetus can "prepare" by
- Reducing metabolic efficiency - Normal/fast rate of organ growth - Normal/fast rate of size growth
high maternal investment continues post-menopausally by
- Slow development - Secondary altriciality - Short interbirth interval
adolescence growth spurt in males
- The adolescent growth spurt occurs late in sexual development, thus males can practice behaving like adults before they are perceived as such
homo erectus locomotion
Fully terrestrial, efficient biped
adolescent growth spurt
There appears to be a suppression of skeletal growth up to puberty followed by a growth spurt after puberty. • No other primate has an adolescent growth spurt.
female RS determined by
female s RS is determined by her access to resources
mode 3
flakes made from carefully prepared cores
infancy
from birth to weaning (0 - 3 years)
kin selection of homosexuality
gay men compensate for their lack of children by promoting the RS of siblings
Human mandible
has a mental protuberance (mentum osseum or chin) and lacks an inferior transverse torus
mode 5 tools
microliths: a minute shaped flint, typically part of a composite tool such as a spear
what process lead to humans spreading around the globe
process dominated by replacement
large brain in homo erectus suggest
prolonged maturation and infant dependency, as in modern humans (although still growing up more quickly than modern humans)
what model receives the most support from fossil record and DNA for modern humans
replacement model
why in colder climates do mammals tend to have shorter and thicker limbs
to minimize loss of body heat.
Ultimate explanations
why humans in general are susceptible to some diseases and not others -Why questions about origins & functions
advantages of mitochondrial DNA (mtDNA)
(1) accumulates mutations 5-15 X rate of nuclear DNA (2) Maternal mode of inheritance - no recombination (3) always transmitted as a single unit (no exchange)
Barker's "Thrifty Phenotype" Hypothesis
*Noticed association between low birthweight and risk of cardiovascular disease in adults • Fetus receives information about nutritional environment from mother • Poor nutritional cues during development causes fetal development to change, so that it will be prepared for an environment in which resources are limited
Modern human behavior characterized by
- Abstract thinking -Planning depth -Behavioral, economic and technological innovativeness -Symbolic behavior
Male Adolescence
- Boys become fertile before they have the size and physical appearance of men. - Males start producing sperm at about 13 years of age.
full reproductive maturation in females
- Full reproductive maturation does not occur until 5 years after menarche; infants born before this time are at risk because of low birthweight, premature birth, and mothers are at risk for high blood pressure
growth of female pelvis
- Growth of female pelvis continues after adolescent growth spurt (around the time of menarche). -Pelvis continues to grow for several years after adult stature is reached and pelvis not mature until at least the age of 18, even in societies with young menarcheal age
Why Did Neanderthals become extinct
- They lacked language - Cultural inferiority (lacked symbolic capacities of modern humans) - Less efficient tools and hunting - Less efficient at processing carcasses (lacked meat and fat storage abilities) - Energetically demanding physiology and life history
Evolutionary paradox of homosexuality: how can a genetically-based trait persist when the individuals who possess that trait have reduced RS?
- allele(s) that influence attractiveness to the opposite sex (e.g. females prefer males with feminine features, or good parenting skills) may sometimes affect sexual orientation (i.e. genes usually increase RS, but not always) - allele(s) could have opposite RS effects in different genders (e.g. being strongly attracted to men; one study in Italy found that the maternal relatives of gay men had higher RS than the maternal relatives of straight men)
Evolutionary legacies: Evolutionary mismatch between conditions in current and ancient environments
- causing inability to synthesize vitamin C was neutral in our primate ancestors-->Results in scurvy when fruit not available -We may not be adapted to: • High population densities • Low levels of physical activity • Other novel aspects of the modern world
what does Africans displaying the greatest degree of variation in mtDNA suggest
- humans evolved in Africa and have been there the longest - human populations in Africa were larger
what does theAmount of variation in mtDNA in modern humans being low show
- humans evolved recently - humans passed through a population bottleneck
Human Revolution
--> modern human behaviors arose suddenly, and nearly simultaneously throughout the Old World about 40-50 kyr --->signals a cognitive advance, a possible reorganization of the brain, origin of language, manipulation of symbols
Neanderthal Nuclear DNA
-A tiny fraction (1-3 %) of non-African modern human DNA seems to have come from Neanderthals
evidence of meat eating for homo erectus
-Acheulean tools are found associated with butchered bones -Hypervitaminosis A in 1.7 Ma skeleton from Koobi Fora. This condition can be acquired by eating carnivore liver
Grandmother Hypothesis
-As women reach the latter part of their lives, it may be better for lifetime RS to start investing in existing children and grandchildren rather than have another baby that she won't be able to see through maturity -Women can continue to invest in their children, and their children's children, by providing food, childcare, knowledge
Predictions based on parental investment theory both sexes
-Both sexes are expected to form long-term relationships, as children with 2 parents have better outcomes (humans grow up slowly). -Both sexes may be open to extra-pair mating opportunities
Acheulean Industry (Mode II)
-Characterized by the "BIFACE": Flake a large core on all sides to create a flat form with an edge along the circumference -Bifaces have standardized forms and regular proportions--> This suggests the knapper had a design in mind.
When did adolescence evolve?
-Comparisons of dental age with skeletal age in young Neanderthal (Le Moustier I) and Homo erectus (Nariokotome Boy) skeletons suggest the human growth spurt had not evolved -The adolescent growth spurt may be unique to Homo sapiens.
Evolutionary legacies:Malfunctional design flaws
-Failure in the choking reflex -"understand the strange fact that every particle of food and drink which we swallow has to pass over the orifice of the trachea, with some risk of falling into the lungs, notwithstanding the beautiful contrivance by which the glottis is closed"
Predictions based on parental investment theory females
-Female parental investment is usually very high. Therefore females will be very selective in choosing mates. (Assume reliable birth control has not been available long enough to change female strategies). Females will be concerned about philandery.
Senescence genes
-Genes causing aging and death have been favored by natural selection. -These genes increase fitness
humans with disturbed FOXP2 gene
-Humans with disrupted FOXP2 (some cases are caused by a single dominant allele) have impaired selection and sequencing of orofacial movements during speaking. - It is therefore speculated that the gene contributes to spoken language.
Mother hypothesis
-Increase the survival and fertility of one s existing offspring, rather than have new offspring
hunting in homo neanderthalensis
-Lacked long distance weaponry -May have suffered from injuries due to close proximity to large game.
genetic evidence that supports the replacement model for modern humans
-Modern humans have shallow genetic roots -DNA suggests a ~recent population expansion from a small population; humans are much less genetically variable than Pan, and African populations are most diverse
features of Homo erectus teeth
-Molars reduced in size -Greater emphasis on tearing and biting with incisors; back of incisors "scooped out" -Brow ridge and occipital torus may be structural reinforcements against stresses associated with tearing and biting
homo neanderthalensis why did they have very large, projecting nose
-Need increased airflow because high activity levels -Need increased surface area to warm and humidify cold air
Neanderthal Mitochondrial DNA
-Portions of Neanderthal mtDNA from numerous individuals have been sequenced and are distinct from modern human mtDNA -does suggest that if they did interbreed, it had no detectable effect on [maternally inherited] mitochondrial portion of the human genome -Neandertals is ~one-third of that in contemporary modern humans, suggesting that the long-term effective population size of Neandertals was smaller than that of modern humans and extant great apes.
Epigenetics of homosexuality
-Sensitivity to testosterone is switched off in female fetuses; if it is switched off in males, it may affect sexual preferences -may involve "hundreds of genes" as well as heritable personality and temperamental traits
Menopause
-The cessation of the menstrual cycle subsequent to loss of ovarian function -Women rarely give birth after the age of 45, even in societies with good nutrition, low levels of physical labor and good health care. -female reproductive system abruptly shuts down before other body systems
features of turkana boy (homo erectus)
-Thick cortical bone (high activity levels) - Long legs (correlated with warm mean annual temperature ~30 ̊C) & narrow hips -Limb proportions like those of modern humans -males were 21 percent heavier
features of homo neanderthalensis
-Very robust and heavily muscled -Scapula with extensive muscle attachments -Longer, more robust distal thumb with broad pulp surface -Pubis a different shape but pelvic outlet no larger than that of modern humans -Hips more widely spaced; decreased locomotor efficiency
Childhood
-after weaning, but still dependent on parent for food; cessation of brain growth at end of stage (3-7 years) - brought on by early weaning relative to the apes; may be a way to shorten the interbirth interval and increase lifetime RS
what does Neanderthal genes that are involved in keratin filament formation suggest
-alleles that affect skin and hair may have helped modern humans to adapt to non-African environments
Regional Continuity Model (multiregional, Candelarbra)
-ancestral Homo erectus populations gradually evolved to modern Homo sapiens throughout the old world -gene flow among populations maintained a single species -modern human populations should have deep genetic roots, since homo erectus was established almost 2 million years ago -regional continuity of skeletal traits and transitional fossils should be found throughout the old world -modern humans should appear almost simultaneously thought the old world (but depends on gene flow) -evidence of hybridization
how is Mitochondrial analysis completed
-by studies of the Y- chromosome (which is only inherited paternally).
Juvenile
-capable of self- feeding but still dependent on parents socially (7-10 years for girls, 7-12 years for boys) - A time of conceptual and cognitive development that includes learning social and economic skills
what makes humans unique
-chin -language
FOXP2 gene function
-codes for a transcription factor that regulates gene expression in the brains of fetuses
time between giving birthed first menstrual cycle is time for
-girls the chance to learn adult behaviors (e.g. complex parenting skills) needed for reproductive success
FOXP2 gene difference in humans
-has 2 amino acid changes compared to chimpanzees -These amino acid differences are caused by nucleotide substitutions at positions 911 and 977 in exon 7 of FOXP2
AMHS (anatomically modern Homo sapiens)
-have longer limbs and a less robust skeleton (e.g., thinner cortical bone) than Neanderthals -AMHS are also less robust than Homo erectus
Homo floresiensis
-hobbit -between 14-40,000 years ago -1 m tall -400ccbrain -dwarfted from homo erectus
Replacement Model (out of Africa, Noah's Ark)
-homo sapiens had a single origin in Africa, then dispersed and replaced other populations with little or no gene flow -No regional continuity of anatomy -replacement -migration events -H. sapiens from Africa -modern human populations should have shallow genetic roots, because they are derived from a recent speciation event -little regional continuity of skeletal traits, except in Africa -modern humans should appear in Africa first -little or no evidence of hybridization
Male preference hypothesis
-if men and women of all ages mate, women's survival and fertility decrease together. -random mutations that affect fertility in older women are not selected against, because men do not want to mate with them. Menopause is thus maladaptive for women.
Female Adolescence
-includes a post-menarcheal period of infertility (1-3 years) (Pan females also experience up to 3 years of anovulatory menstrual cycles after menarche)
how did the socioeconomic organization of human groups effect humans
-increased population density, increase in group size, individuals lived longer (60), had less injury and disease -more elaborate shelters and more structured sites with hearths, pits, huts and tents.
Compared to H. erectus, H. heidelbergensis has these derived traits
-larger brain (12000 cc) -less projecting face -higher skull -no pointed occipital torus -smaller premolars and molars -Thinner cranial bones (but still thick)
what does it mean to be the genus homo
-larger endocranical capacity (in brain size) -decrease in tooth size -tool users -fully committed to terrestrial bipedalism
homo neanderthalensis projecting face
-may be adapted to resist torsion from high bite forces.
what was the nature of the behavioral transition to modern behavior?
-more elaborate tools -shift from flakes to blades
adaptive advantages of chin
-reduction of mechanical stress -Reduction of testosterone levels as humans adapted cooperative behavior -sexual selection
genetic parents in industrialized countries who give up child to someone else
-regretfully give up children when cannot afford to raise them
Microsatellites
-short stretches of DNA that contain many repeats of 2-5 nucleotide segments. -They evolve rapidly, and analyses of these regions suggest an origin of modern humans at 156 ky.
genetic parents in oceania when give up child to someone else
-still look out for welfare of child -regretfully give up children when cannot afford to raise them
Adoptive parents in Oceania
-usually closely related to offspring -have no dependent children currently or are wealthy
mode 3 tools function
-variable -May reflect different activities including butchery and woodworking.
Adoption in nonhumans
-voluntary extended care of another s young is uncommon
handax functions
1) Butcher large animals 2) Dig (tubers, burrowing animals) 3) Strip bark 4) Thrown at prey 5) Source of flakes
Why we get sick: Darwinian medicine
1. Genetic trade-offs 2. Evolutionary legacies 3. Co-evolution of pathogens and hosts 4. Evolution is about fitness, not health
Schematization of factors associated with the increased risk of obesity in the industrialized nations
1. Low Physical Activity 2. Consumption of foods rich in fat and sugars 3. Consumption of high density and low cost foods
Schematization of factors associated with the increased risk of obesity in the developing nations
1. Low Physical Activity 2. Consumption of foods rich in fat and sugars 3. Consumption of high density low cost foods 4. Expression of the "thrifty gene"and Chronic Undernutrition
Pathogens advantages
1. Reproduce & evolve rapidly 2. Larger numbers
antibiotic Variation
Bacterial resistance to antibiotics arises through rare mutations
evidence modern behavior shows up well before humans herein Europe
Blades -in Kenya @ 285,000 - in Ethiopia @ 180,000 -in South Africa @ 80,000 Transport of obsidian - from Kenya to Tanzania (300 km) @ 130,000 Marine exploitation of resources -@ 125,000 in Eritrea Fine bone tools - @ 70,000 in South Africa Barbed harpoons and bone tools - @ 130,000 in Congo
what does both mtDNA and y-chromosome show
Both MtDNA and Y-chromosome data have shown that some ancestral DNA signatures still persist in modern Khoisan people of Sub-Saharan Africa and can be dated to 120-145 ky.
brain size of homo neanderthalensis
Brain: 1245-1740 cc; avg. = 1520 cc
Proximate explanation of heart attacks
Eating fatty foods and having genes that predispose to atheroscelerosis* are major causes of heart attacks
high variability in Dmanisi sample used to argue that...
Homo habilis/ rudolfensis/ergaster/erectus all one species: Homo erectus
large teeth in homo neanderthalensis
Large, worn anterior teeth suggest paramasticatory activity (e.g. may have pulled meat or hide through clenched teeth; this inference is supported by microwear)
Reduction of testosterone levels as humans adapted cooperative behavior
Less testosterone = smaller/softer craniofacial structure behind chin, making the chin prominent
predictions based on parental investment theory males
Male parental investment may be very high. Therefore males will be very selective in choosing mates. Males will be sensitive to loss of female fertility at ~45. Males will be concerned about being cuckolded. -males may be more sensitive to mating opportunities that do not involve long- term commitments.
FOXP2 gene in Neanderthals
Neanderthals also possessed the function the 2 amino acid substitutions have for language ability.
Modern humans appeared in Africa well before....
Neanderthals disappeared from Eurasia
what was the purpose of portable art?
Need to communicate abstract information by means of symbols
conception
Poor nutritional cues during development cause fetal trajectory to change by turning certain genes "on", so that it will be prepared for an environment in which resources are limited
Hypotheses for the evolution of the chin Biomechanical explanation 2:
Speech stresses the mandibular symphysis due to tongue and orofacial muscle activity, i.e. the chin resists stresses caused by oblique contractions of the genioglossus muscle during speech.
HANDAXE (very common)
Teardrop shaped with sharp point
Competition and differential reproduction of antibiotics
The presence of an antibiotic causes the initially rare mutant strain to increase and gradually replace the ancestral type
Ultimate explanation of heart attacks
Why hasn't natural selection eliminated the genes that promote craving for fat and cholesterol deposition
Compared with modern humans, Homo erectus has
a larger face, lacks a chin, and has a more angular vault and smaller brain
Evolutionary legacies
a. Malfunctional design flaws b. Evolutionary mismatch between conditions in current and ancient environments
where are living humans derived from?
africa with an origin b/t 100-200 ky
Adolescence
after onset of puberty, but before skeletal maturity (from 5-8 years after onset of puberty)
Adulthood
after skeletal growth in stature ceases (> 20 years)
homo erectus behavior
better made Acheulean tools, big game hunting, fishing
mode 4 tools
blades
Human chin
can be divided into regions and exhibits sexual dimorphism
Antibiotics
chemical warfare agents that evolved in fungi and bacteria to protect them from pathogens. They have been shaped by millions of years of natural selection to exploit the vulnerabilities of bacteria while being non-toxic to hosts.
Two life history stages humans have that no other primate has
childhood and adolescence
Hypotheses for the evolution of the chin Sexual selection hypothesis:
chin shape variation is a consequence of sexual selection; studies of facial attractiveness suggest that a "broad chin" in males is correlated with social dominance
male RS determined by
his access to fertile females
Developmental History
history of individual since conception
Classic Medical History
history of individual's complaints and illnesss
evolutionary History
history of individual's lineage
Proximate explanations
how the body works and why some people get sick while others don't -What & How questions about structure & mechanisms
how was upper paleolithic blade technology different?
made more efficient use of raw material than earlier tool technologies did because blades had longer cutting edges per pound of raw material
homo erectus body size
increase in body size -decrease in body size dimorphism
homo sapines change in skull
increase in cranial volume, decrease in robusticity.
5 stages of human life history
infant-child-juvenile-adolescent-adult
Homo heidelbergensis what derived features does it lack
lacks the derived features of modern Humans (e.g. chin) and Neanderthals (e.g. huge nose).
primitive traits persist in homo heidelbergensis
large face sloping forehead supraorbital torus
Secondary altriciality
selection for encephalization (larger size of brain) coupled with obstetric limits of bipedality led to infants who experienced significant postnatal brain growth
transition from H. erectus to other forms of homo was what kind of transition
slow, widespread, uneven process
abstract thinking
the ability to act with reference to abstract concepts not limited in time or space
planning depth
the ability to formulate strategies based on past experience and to act upon them in a group context
Symbolic behavior
the ability to represent objects, people, and abstract concepts with arbitrary symbols, vocal, or visual, and to reify such symbols in cultural practice
Hypotheses for the evolution of the chin Biomechanical explanation 1:
the chin acts as a buttress against masticatory stress (i.e. in absence of inferior transverse torus)
Penicillin resistance
• In 1941, all staphylococcal bacteria were vulnerable to penicillin. • By 1944, some strains had already evolved resistance. • Today, nearly all staph is resistant.
Genetic trade-offs: Sickle cell anemia
• Sickle cell anemia is caused by a single, recessive allele, S (alternative allele = A) • SS homozygotes are lethal • Frequency of S is 10% or more in some W. African populations • S allele increases fitness of AS heterozygotes by protecting them against malaria • Where malaria is prevalent, AS heterozygotes are 15% more likely to survive to adulthood than AA homozygotes
Tuberculosis
• TB is a common cause of death in developing countries, with nearly 2 million people succumbing each year. • About 1⁄2 million cases of multi-drug resistant TB occur every year
number of children per women influenced by
• age at menarche • age at menopause • interbirth interval - Energy balance - Breast feeding (causes lactational ammenorhea)
Adaptive explanations for menopause
• females who stopped reproduction before the end of their lives had a selective advantage over still- fertile conspecifics • effort better directed toward existing offspring, rather than new offspring
Cultural arrangements help to
• minimize male- male competition (as does concealed ovulation?) • protect females from mating aggression • maximize paternity certainty
adoptive parents in Industrialized Countries
• often couples who cannot procreate • have no dependent children currently or are wealthy
