Ultimate Flashcard Extravaganza

1
Q

Evolution Before Charles Darwin

A

Enlightenment - no divine right to rule, natural phenomena are mechanically caused by external forces
Erasmus Darwin - Charles’ grandfather, organisms’ sensitivity to the environment shapes their minds and bodies, better forms have increased over time
Jean-Baptiste Lamarck

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2
Q

Jean-Baptiste Lamarck

A
  • animals have an internal drive to physically accommodate to environmental conditions and become more complex
  • persistently successful accommodations can become so habitual that they become physiologically based and get passed on to offspring
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3
Q

3 Influences of Darwin’s Theory

A
Charles Lyell (geologist)
Thomas Malthus (economist/demographer)
Alfred Russell Wallace (naturalist)
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4
Q

Charles Lyell

A

geologist, friend of Darwin

argued for a very slow and incremental pace of geological change

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5
Q

Thomas Malthus

A

economist and demographer
emphasized danger of uncontrolled human reproduction with limited resources
helped Darwin see the role of resource competition

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6
Q

Alfred Russell Wallace

A

independently discovered the theory of natural selection; letter prompted Darwin to submit their theories together in 1859

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7
Q

“Survival of the Fittest”

A

“fitness” is really “fittedness” - term was coined by Herbert Spencer, not Darwin
fitness is not determined by health or strength, but by reproductive success and ability to adapt to environment

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8
Q

3 dimensions of biological analysis

A

length - longitudinal analysis (homology)
breadth - comparative analysis (analogy)
depth - functional analysis (physiology)

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9
Q

How nature “backs up” her data

A
  1. Things naturally tend to fall apart and complicated mechanisms tend to wear out and fail
  2. One defense is to make copies
  3. Copying is never perfect - variation is inevitable
  4. Copying takes time and energy
  5. Some copying processes will be more profligate or successful than others
  6. Favored copying processes will be ones that best “fit” the conditions
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10
Q

Herbert Spencer

A

coined the phrase “survival of the fittest”
argued that evolution argued by Lamarckian use-inheritance
believed that learned habits could be passed on by reproduction –> social progress could lead to biological progress
argued that “primitive” societies were less evolved “races”

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11
Q

Haeckel and Progress

A

argued that evolution tends toward greater complexity

humans were presumed to occupy the highest rung on the biological ladder and were “the most evolved”`

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12
Q

Why Evolutionary Misconceptions are Wrong

A

Evolution is not linear and not necessarily progressive.
Its tendency is to diversify and expand into novel niches.
Evolution spontaneously tends toward increasing complexity because there is nowhere else to go.

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13
Q

“Planet of the Apes” Fallacy

A

nothing about natural selection produces inevitable trends, even improvement
humans didn’t replace or improve upon apes

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14
Q

Types of Selection

A

stabilizing selection - selection against extreme phenotypes that deviate from the mean
directional selection - selection favors extremes
disruptive selection - either extreme is favored
eg Japanese pheasants

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15
Q

The Red Queen analogy

A

the environment is always a moving target
it can look like there is an “arms race” between organisms adapting to the same environment, but they are just trying to keep up with the same changing environment
sometimes you have to run fast just to stay where you are

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16
Q

Mendel’s Basic Discovery

A

simple traits are controlled by an interaction between the two “doses” of each gene type (allele) that are present in each plant
because of this, they can interact or mask each other’s effects (dominant/recessive)
independently assort in subsequent generation according to simple binomial rule

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17
Q

Protein Functions

A

catalysts - aid chemical reactions, eg digestive enzymes
structural elements - or link other molecules, eg skin and hair
recognition or signaling - for cell cell communication
molecular “chaperones” - for other molecules that bind or transport eg hormone receptors and hemoglobin oxygen transport

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18
Q

SNPs

A

single nucleotide polymorphisms; different people can have different bases in a specific location
can be used for identification, diagnosis, and tracing ancestry

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19
Q

Genetic “drift”

A

statistical sampling effects producing random selection
there is always a 50% loss in genes from each parent
sex leads to inevitable gene elimination by chance

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20
Q

Founder Effect

A

a small group initially founds a population and diversifies from there
reduces genetic diversity

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21
Q

Why shift to a genetic perspective?

A

all bodies eventually perish! what persists are the genes that contribute to those traits

but: the particular combination of genes and traits that constitute an individual will likely never recur, except for in identical twins and asexual species
eg. Secretariat effect

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22
Q

Sickle Cell Anemia

A

sickle cell is only produced by the genetic mutation if both hemoglobin A molecules are sick type
hetereozygotes have 50% hemoglobin beta exhibiting mutation, which does not cause anemia but a low level of cell damage
this is sufficient to expose the malaria parasite to the immune system and help eliminate it
so: sickle cell heterozygotes are positively selected for
balanced polymorphism

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23
Q

Mitochondrial DNA

A

not contained within the cell nucleus but within the organelle
mitochondria are passed on in the cytoplasm of the ovum and therefore come only from the mother
mtDNA has bacterial origin!
(Y chromosome DNA is similar - only passed through male lineage)

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24
Q

Y chromosome inheritance

A

long arm of the Y chromosome does not recombine in sexual reproduction
inherited intact from father to son
therefore transmitted in all or none fashion and can be traced from individual to individual

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25
gene duplication --> functional divergence
eg hemoglobin: spontaneous degradation of duplicate genes produced beta-hemoglobin variants with different oxygen affinities problem of transferring oxygen from maternal to fetal hemoglobin provides "functional niches" that variant hemoglobins can fit
26
Regulatory Genes
produce proteins that control patterns of gene expression in the different cells of a body
27
Extended Phenotype
selectively favored effects are expressed outside the body that produces them genes can produce molecules whose primary focus is to control another species' development or behavior
28
Death as a Reproductive Strategy
trade-off point between maintaining a body and instead putting that energy into reproduction is different for different species/life stages salmon kill themselves in an effort to arrive upstream ahead of competitors and produce hundreds of offspring mantis males easier to be caught and eaten late in the breeding season when chances of reproducing are slim and nutrition from eating their bodies could aid female reproduction
29
Sex has evolutionary costs
1. only a random half of one's genome gets passed to each offspring, and some genes don't get passed on 2. good gene combinations tend to get broken-up in each generation (Secretariat effect) 3. time and resources are required to locate a mate, and often in fighting for mates 4. probability of encountering a potential mate is reduced by 50% 5. males use up resources and don't contribute to offspring nourishment and health
30
Sex requires social interaction
- over the course of evolution, sexual reproduction has played the dominant role in promoting social behavior and cooperative organization within a species - by distributing mutually exclusive reproductive adaptations among different individuals the advantages and disadvantages of each are separated - traded off against the costs of making autonomous reproduction impossible, resulting in different combinations of sexual traits
31
sexual reproduction involves a mix of:
1. Recombination (genes) 2. Anisogamy (sperm and ova) 3. Gender (male and female)
32
Why recombination?
genes must work in combination with one another necessary to have them linked to keep working combinations together during reproduction but this risks having a damaged gene ruin the reproductive chances of any linked gene periodic recombination (shuffling) allows genes to escape linkage with "bad" genes
33
Anisogamy
"not the same gametes" different gamete phenotypes: usually haploid, as in ova and sperm sperm selected for: high numbers, low production costs, easy dispersal, high genetic diversity --> small, mobile, expendable ova selected for: robustness, ample metabolic resources --> large, immobile, easily protected
34
Hermaphroditism
(both kinds of gametes) requires a compromise with respect to gender-distinct bodies where both dispersal-variation and investment-protection can be independently maximized usually in conditions where access to mates is reduced
35
Sex vs. Body Gender
sex - typically understood in terms of male and female, used to refer to either whole animal bodies or to the organs of reproductions in plants that carry sperm (pollen) or ova (egg cells) gender - linguistic designation of nouns and pronouns typically into masculine, feminine, and neuter grammatical types; has come to be used by analogical extension to refer to masculine vs feminine "roles" aka GENDER IS A SOCIAL CONSTRUCT
36
Conditions that Favor Asexual Reproduction
minimal competition for resource predictable conditions higher reproductive rate, lower variation
37
Conditions that Favor Sexual Reproduction
significant competition for resources unpredictable conditions lower reproductive rate, higher variation
38
Blue-Headed Wrasse
sex change all begin life as females live in a school defended by a single male, who is much larger on average, has a distinct blue head, and inseminates all eggs of the school if this male dies, the larger females will compete and one will transform into a male developing a blue head
39
Anemonefish
"clownfish" have an ability to prevent anemones from stinging them pairs "nest" in an anemone where they raise young who can feed off prey paralyzed by anemone begin life as males capable of producing sperm young males pair up with older females who have successfully defended an anemone "nest site" in which to raise the young older female dies, younger male undergoes a sex change to become a female and gonads begin to produce ova young males will be attracted to mate with female
40
Darwin's Theory of Sexual Selection
explains the evolution of apparently nonfunctional, superfluous, or harmful traits including human intelligence emphasizes Darwin's focus on reproduction basic logic - reproductive competition not only dissociates members of a species into distinct sexes, but can lead to competition within the same sex for access to reproduction
41
Darwinian Logic of Sexual Selection
1. better reproduction is more important than optimizing survival or access to resources 2. there are often major differences in an individual's reproductive output 3. possibility of increasing reproduction could lead to competition for mates 4. traits that trade health and survival for reproductive advantages will evolve where not blocked by natural selection
42
Modern Logic of Sexual Selection
- sex that contributes more time, energy, and risk in support of offspring is "limiting resource" for other sex - sex that invests more evolves greater discernment of mates; sex that invests less evolves a means to bias the selection in its favor by increasing the total number of mates - manipulation of mating changes may occur via aggressive exclusion of competitors, competition over valued resources, promiscuity, risky displays that signal health or vitality
43
Displays as Handicaps
eg widowbirds widow bird males have long tails that attract both females and predators experimental manipulation shows that females prefer longer than normal tails
44
Tournament Reproductive Strategy
about 98% of mammals, sexual dimorphism, male energy largely devoted to competition and no male parental investment, high variance in male reproductive success male display; female choice high polygyny - rival males are excluded
45
Pair Bonding Reproductive Strategy
95% of bird species sexual monomorphism, male energy divided between competition and parental investment, low variance in male reproductive success mutual courtship low degree of polygyny, some polyandry, mostly mated pairs
46
Male Defense: either resources or females
resource defense - males compete for territories that attract females, who spend more time there and are available for mating female defense - food is widely distributed and females feed in groups, so males compete to prevent other males from mating with them
47
Bowerbirds
competing for mates using artifacts: male bowerbirds attract mates with elaborately constructed and decorated displays (bowers) that only superficially resemble nests females will mate in the bowers and then raise young on their own males compete for attractive objects to decorate their bowers, often stealing from other bowers
48
Factors contributing to pair bonding
- offspring that require extensive or prolonged care to reach a stage where they can forage for themselves - non-abundant, non-clumped food resources - limited nest or burrow sites, or sites requiring defense or significant effort to produce - low population densities
49
Bird and Mammal Cooperative Care
- cooperative rearing strategies are generally rare, but can be found in environments where resources (like nesting sites) are rare - because defending a nest site poses additional demand, sometimes this can require more than one male and one female - in these conditions it may be advantageous for fledglings to remain with parents, feed and defend the new brood until they gain skills to successfully establish a new nest
50
Helper-at-the-nest
larger the "clan" the better the nest site they can cooperatively defend helpers' short term postponement of their own reproduction is not a cost because it is unlikely that on their own the young offspring would survive by assisting their parents during this time they are passing on their genes "by proxy"
51
Lions
female lions - social carnivory, they cooperatively hunt and cooperatively care for offspring so while many females can hunt many others can remain behind to care for cubs male lions - compete to defend a pride of females, commit infanticide when females are not in estrus with the previous pride lion's cubs still nursing
52
Reciprocal Altruism in Vampire Bats
vampire bats roost in large social groups feeding is highly unreliable and high metabolisms make them susceptible to starvation and dehydration at some point most individuals will require supplemental feeding from roost-mates
53
Conditions Favoring Reciprocal Altruism
low cost to giving aid, high benefit of giving aid long-term association allows ample time to reciprocate and assess reciprocation means of identifying individuals means of punishing/exclusive non-reciprocators
54
Obligate Social Living
not just male and female - eg ants and bees can lead to segregation of gender functions into more than 2 body types 1. drone (haploid male, fertile) 2. queen (diploid female, fertile due to added hormones) 3. worker (diploid female, sterile due to lack of hormones)
55
Honeypot Ant Eusociality
- workers act as storage vessels called "repletes" for honey used to feed brood and others - specialized workers store honey in their abdomen for the colony to use when resources become scarce - specialized body types are a form of "kin" altruism
56
Termite Eusociality
exception that proves the rule about kin selection colony inbreeds generation after generation, resulting in very high levels of relatedness have many non-reproductive "castes" with distinct body types and behavioral predispositions gender roles are determined by hormones and pheromones as well as season, size, age of colony fertilized females (queen gives birth to both males and females) will attempt to establish their own colony
57
Naked Mole Rat
a eusocial mammal live in underground colonies, produced by a single breeding female who suppressed fertility of male and female workers with pheromones a few breeding males also act as guards if colony is threatened highly inbred, like termite colonies workers dig elaborate tunnel systems and bring food back to the breeding chamber
58
Colugo "Flying Lemur"
``` closest "outgroup" to primates location: Southeast Asia not a primate or a bat, arboreal glider frugivory-insectivory uniparous, carries young ```
59
Tupaia "Tree Shrew"
``` next closest outgroup to primates arboreal locomotion insectivorous grasping hands, primate-like ears, binocular vision large snout/nose ```
60
Initial Primate Specialization 65 MYA
arboreal, noctural, insectivore/carnivore large, forward-facing eyes clinging-leaping-grasping single birth, carries young arboreal nocturnal hunting requires the ability to see in the dark and judge depth
61
Prosimians: Tarsiers
SE Asia, nocturnal hunter of insects, frogs, reptiles clinging-leaping solitary hunters, pair bonds and small groups glaborous fingertips
62
Prosimians: Galagos ("Bush Babies")
nocturnal, clingers and leapers gumivory and insectivory pair bonding with joint territory defense multiparous litters nest in hollow trees where young are left
63
Prosimians: Lemur Catta ("Ring Tailed Lemur")
highly social, live in large multi-male multi-female groups, dominance hierarchies and male-male competition tails are used for social communication
64
Lemur Diversity
typically diurnal, reduced eyes and enlarged snout with wet nose include frugivores, folivores, and insectivores include solitary and group living species ancestors of lemurs were isolated on Madagascar with few predators or competitors and differentiated into diverse species with diverse adaptations
65
Prosimians
smaller bodies, smaller social groups, un-fused mandible, more insect and gum eating, nocturnal, some reliance on olfaction, limited color vision
66
Anthropoids
larger bodies, larger social groups, fused mandible, more fruit and leaf eating, diurnal, even less reliance on olfaction, extensive color vision
67
Locomotion
prosimians: clinging and leaping | monkeys and apes: arboreal quadrupeds, terrestrial quadrupeds, suspensory motion
68
Origin of the Anthropoid Primates
``` shift to diurnal feeding on fruit fruit co-evolved with birds as seed dispersers changes: 1. reduced eyes 2. change in tooth structure 3. reduced muzzle and nose 4. closure of the orbit ```
69
Loss of Vitamin C Synthesis
result of the shift to frugivory 1. ascorbic acid not in diet = selection for endogenous synthesis 2. dietary substitution 3. dependence and re-adaptation
70
Color Vision
fruit initially evolved for seed dispersal by birds, which have good color vision ripeness indicated by color dependence on dietary ascorbic acid associated with selection for 3-color vision, changes in taste receptors, tolerance for alcohol (from over-ripe fruit), etc
71
New vs Old World Monkeys
NWM - platyrrhine (outward facing nostrils), 3 premolars, can have prehensile tails OWM - catarrhine (downward facing nostrils), 2 premolars, never have prehensile tails
72
New World Monkeys: Assortment
marmosets - gumivores, defend territory owl monkeys - convergent adaptations with prosimians, only monkey adapted to nocturnal foraging spider monkeys - locomotion using prehensile tail howler monkeys - defend territory using loud vocalization aided by an enlarged lower jaw and hyoid bone uakari - Ally Boville
73
Old World Monkey Specialization
bilophodont molars, ischial callosities diverged from apes with respect to locomotor adaptations (quadrupedal monkeys vs suspensory apes) OWM further diverged into two groups with respect to dietary adaptations and specialized digestion (folivorous colobines vs omnivorous cercopithecines)
74
Colobines
specialized group of Old World Monkeys with adapted digestive system for folivorous diet arboreal quadrupeds
75
OMW Arboreal Quadrupeds
equal length arms and legs, rigid lumbar spine, four grasping hands, horizontal body
76
Cercopithecines
omnivorous includes baboons, macaques, guenons terrestrial quadrupeds
77
OWM Cercopithecines: Macaques
cheek pouches allow them to carry extra food without eating it live in multi-male, multi-female troops males usually emigrate from their troop to a new one while females stay with kin males often form small coalitions female dominance inherited from mother's rank
78
Advantages of Monkey Sociality
``` defense of patchy resources predator defense grazing tracking social transmission of foraging kinship continuity (of one sex) ```
79
Disadvantages of Monkey Sociality
sexual competition feeding competition male paternity uncertainty
80
Infanticide in Langur Monkeys
Hanuman <3 langurs live in large single dominant male polygynous troops when the dominant male is deposed, the new male systematically attacks and kills infants this brings females back into estrus females may feign sexual receptivity in order to protect their infants
81
OMW Cercopithecines: Baboons
widespread in sub-Saharan Africa and live in large multi-male, multi-female groups that tend to forage on the ground mandrills: baboon species that live in forests, form single-male polygynous groups and have been known to kidnap females from other groups; most sexually dimorphic baboons gelada baboons: forage on grasses in very large troops of smaller harems controlled by highly aggressive dominant males
82
Southeast Asian and African Apes
apes are far less numerous than monkeys, range is restricted to tropical forests of Africa and SE Asia reflects primary adaptations for aboreal locomotion and foraging range of apes used to be significantly greater 10-20 MYA
83
Ape Locomotor Adaptations
lack of tail, long curved fingers, highly mobile shoulder girdle and hip joint, shortened thumbs, four grasping limbs, vertical posture, mobile lumbar vertebrae, conical rib cage, wrist rotation, scapulae (shoulder blades) located on back
84
Asian Apes: Gibbons
small frugivorous brachiators specializations for brachiation, coupled with small body size, predispose gibbons to walk bipedally when on the ground gibbon pairs cooperatively defend a territory by singing duets twice a day each sex drives off rivals of the same sex
85
Asian Apes: Siamangs
like gibbons, sing to defend territory (but only males sing) and also pair bond specialized throat pouches for long distance vocalization
86
Asian Apes: Orangutans
Borneo and Sumatra sexually dimorphic, males distinguished by fat pads locomotion - quadra-manual, suspensory, mixed terrestrial forms of locomotion also: infant ventral clinging and dorsal riding isolated foraging
87
Orangutan Terrestrial Locomotion
variety of knuckle-, fist-, and wrist- walking strategies
88
African Great Ape Habitats
African apes except humans are confined to the equatorial forests (this environment is not good for fossilization) Gorillas and chimpanzee habitats overlap, but bonobos are separated by the Congo River
89
African Apes: Gorillas
- folivorous, enabled by large digestive systems - most of the day is taken up with eating and moving - single large dominant "silverback" male with 3-8 females, infants, and some adolescent males - no distinct territories and forage over large areas - mature males develop silver hair on their backs and defend troop females, while young males attempt to abduct females and form new troops
90
Gorilla Group Structure
``` single dominant, sexually dimorphic "silverback" male mobile female-group foraging female-defense polygyny female transfer (abduction) male emigration to form a new group ```
91
Gorilla Locomotion
Terrestrial: mostly knuckle-walking but some bipedal walking is possible Arboreal: possible but limited by size, more common in females
92
African Apes: Chimpanzee
Pan troglodytes - Central and West Africa omnivorous, arboreal and terrestrial foraging knuckle-walking large multi-male, multi-female social groups male cooperative territory defense male hunting of monkeys
93
Chimpanzee Foraging Patterns and Emigration
individual females and young forage together in male-defended territories female foraging territories overlap with each other females leave their natal troops at puberty to join nearby male territories, while males remain with their natal troops
94
Chimpanzee Male-Kin Coalitions
reduced male-male aggressive competition, male hierarchy weakly limits sexual access female fertility is advertised by perineal swelling and active solicitation during estrus male kin-cooperation: extensive repertoire of social communication, involving vocalization/grooming/tactile contact
95
Chimpanzee Group Structure
multi-male, multi-female groups modest sexual dimorphism territory defense by male coalition female transfer/ male continuity
96
Chimpanzee Tool Use
transmission of tool use by observation and crude imitation; no clear evidence of "training" mastering a complex skill may take many years also seen in capuchin monkeys made possible by combination of continued social living, need to extract difficult foods, hands, large brains
97
Chimpanzee Hunting and Violence
males engage in regular cooperative hunting of colobus monkeys kills are shared with females and young male groups may attack and kill isolated males from neighboring troops infanticide of infants brought into territory may also occur
98
Chimpanzee Infanticide
female "troop transfer" occurs when she reaches young adulthood, may be pregnant at this time males and females will often harass new females in the troop and can kill an infant she is carrying females have also been known to kill infants of other females within the same troop
99
African Apes: Bonobos
Pan paniscus - Central African forests omnivorous, forage in large multi-sex multi-age social groups minimal dominance hierarchy, weakly territorial, highly sexual bonobos do not overlap with chimpanzees and therefore are not in competition for the same foods
100
Bonobo Locomotion
versatile locomotion: agile arborealists, and on the ground both knuckle-walking and bipedalism are common foraging on the ground may require use of arms for carrying food and offspring while erect; infants usually ride dorsally
101
Bonobo Social Structure
mobile multi-male, multi-female foraging groups territorial but with minimal territory conflict and common troop exchange, mostly females minimal dominance hierarchy not predictive of mating priority, females often dominant over males, males inherit rank from mothers
102
Bonobo Sexual Behavior
sexual swelling in females is extensive and long-lasting and accompanied by intense interest; as a result, same-sex stimulation among friends is common interactions may involve many individuals of any sex or age why so frequent? food is widely available, not season, no hunting no competition with gorillas, etc., for ground-based foods minimal male-male competition, social groups are large and all individuals forage together
103
Chimpanzee vs Bonobo Sex and Social Function
chimpanzees: highly competitive male access, minimal male-female bonding, minimal same-sex copulation bonobos: no sexual competition, strong male-female friendships, considerable same-sex copulation with friends
104
Sahelanthropus tchadensis
``` possible hominin or ape ancestor or both mixture of traits: -small brain -small teeth, canines -heavy brow ridge -elongated skull -large orbital torus ```
105
Orrorin tugenesis
small teeth with thick enamel femora show evidence of bipedal locomotion but not conclusive upper limb evidence of climbing adaptation could be prior to pan/hominin split
106
Ardipithecus ramidus
4.4 to 5.8 MYBP woodland habitat anterior position of foramen magnum = upright posture and likely bipedalism molars intermediate between chimp and australopithecine larger canines than australopithecines, broader than in chimps
107
Suspensory locomotion - common ancestral condition?
evidence: 1. more horizontal ilia, cup-like pelvis 2. open mobile lumbar spine 3. more vertical posture, but 4. short legs, short arms
108
Australopithecines
bipedal apes with large thick enamel teeth, reduced canines, ape-size brains, high sexual dimorphism, savannah or open woodlands, mostly vegetarian diet
109
Australopithecine Body
``` compromise of locomotor adaptations 1. broad horizontal pelvis 2. extended "free" lumbar vertebrae but! 3. rib cage of a climber-brachiator 4. long curved fingers and slightly diverged big toe of a brachiator ```
110
Australopithecine: Small Stature
australopithecines were much smaller than modern humans would make upright locomotion preferential for a suspensory adapted body frame (like gibbons) ratio of weight to stature increases with size
111
Australopithecus africanus
3.6 MYA 6 lumbar vertebrae (one more than humans, 3 more than chimps) further evidence against knuckle-walking ancestry also bipedally adapted pelvis and femur
112
Australopithecine Teeth
reduction of canines and diastema regressive in all australopithecines greatest in early species, most reduced in later robust species
113
Australopithecus amanensis
3.9 to 4.2 MYA obligate biped 20% larger than A. africanus, sexually dimorphic larger molars than Ardipithecus, thicker enamel large elongated canines
114
Australopithecus afarensis
2.9 to 3.6 MYA clear bipedal adaptations: knee angle, wide bowl-shaped pelvis massive face, jaw, molars canines still protrude beyond tooth row and slight diastema significant sexual dimorphism
115
Australopithecus robustus
1 to 2 MYA large zygomatic arch and sagittal crest maybe from africanus?
116
Australopithecus aethiopicus
2.5 MYA | small brain, posterior foramen magnum, massive sagittal keel, and wide zygomatic arch
117
Australopithecus boisei
``` 1.2 to 2.3 MYA massive molars with extensive wear reduced canines and incisors sagittal crest broad zygomatic arch gorilla size brain likely lived at the same time (1.2 MYA) as some Homo species ```
118
Australopithecus sediba
many intermediate features long thumb, shorter stubby fingers shape of the pelvis is not as wide as other australopithecines (center) and more like later Homo
119
Australopithecus garhi
2.5 MYA large molars and incisors, sagittal crest femur elongation evidence of stone tool use: -broken and scratched bovid and horse bones -show regular parallel linear scratches -Oldowan type stone chips found at site
120
Oldowan Tools
Gona, Ethiopia 2.4 MYA used by A. garhi, H. habilis, H. rudolfensis, early H. erectus/ergaster appear to have been made "as needed" at butchery sites more evidence of scavenging than hunting
121
Australopithecine vs. Homo adaptations
Australopithecine - bipedal with some suspensory adaptations, grassland habitat, large molars, reduced canines, ape-size brain, high sexual dimorphism Hominine - fully bipedal, no suspensory adaptation, diverse habitats, small jaw and molars, canines, stay small, enlarged brain, low sexual dimorphism
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Homo habilis
1.8 MYA small molars, thin enamel, reduced incisor reduced face, rounded cranium, 550 cc brain reduced sexual dimorphism Oldowan tools
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Homo ergaster
1.75 MYA small molars, thin enamel, reduced incisors reduced face, rounded cranium, and 850 cc brain reduced sexual dimorphism extensive Oldowan tools
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Homo rudolfensis
1.8 MYA large brain (775 cc) rounded vaulted cranium heavy flat face large incisors and canines compared to molars first species with a brain size larger than other apes Australopithecus face; Homo brain
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Homo naledi
currently classified as a transitional species because that is the most parsimonious strange (cave) location in which it was found some evidence to suggest a much longer persistence of australopithecines
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Homo ergaster
1.75 MYA larger brain (850 cc), rounded cranium reduced face and zygomatic arch reduced molars, thin enamel, small canines compared to incisors extensive Oldowan usage robust but otherwise modern post-cranial skeleton, but smaller brain/long robust skull coexisted with A. boisei for a while (did they hunt boisei?)
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Transition to homo ergaster
marked by an increase in both body size and brain size over any australopithecines all correlates of arboreal adaptations vanish loss of sexual dimorphism
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Acheulean tool technology
first appear in Africa between 1.5 and 1.2 MYA sharp bifaced tools with complex shaped edges, made from carefully selected stone materials some of the sharpest are made from volcanic glass rare in Asia
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The Mind of Homo Erectus
brain size (900-1200cc) is in the low modern range (1000-2000cc) sexual dimorphism similar to modern humans highly mobile societies stable foraging adaptation adaptation to diverse ecosystems no external symbols (artwork)
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Homo heidelbergensis
``` 700,000 years ago modern brain size (1500-2000 cc) elongated cranium robust face, with large orbital torus prognathic, high forehead ```
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Homo neanderthalensis
confined to Europe and Middle East, including Iraq and Israel from 120,000 to 30,000 years ago brain size above the modern average size less prognathous robust face, orbital torus, large nose, extensive turbinates exhibit many distinctive skeletal features shared with earlier homo species but not modern ones extinction likely caused by low temperatures
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Mousterian technology
multiple stage tool manufacture with preparation of cores to better produce shaped flakes with broad continuous edges =complex planning and visualization of an indirect consequence specialized points; possible hafting
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Neanderthal DNA
possible to do genetic testing because not always fully fossilized (this is not true of any other ancestor) likely interbred with eurasians some likely had fair skin and red hair, some had brown eyes and brown hair deliberate Neanderthal burial sites have been found; evidence shows they cared for the infirm and elderly may have had complex cultural traditions and beliefs
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Tracing "Y Chromosome Adam"
long arm of the Y chromosome does not recombine in sexual reproduction inherited intact from father to son therefore transmitted in an all or none fashion and so can be precisely traced from individual to individual without loss "rooted" in Africa because the greatest genetic differences between individuals are found in Africa
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Low Genetic Variation
suggests a recent common origin from a small population all modern humans show less gene diversity than small populations of nonspecific apes even Neanderthals are closer to humans than different chimp populations are to one another genetic evidence: all modern human populations and "races" diverged from a common African population as recently as 70,000 years ago
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Body Lice
diversification suggests that migration out of Africa may have involved the first continuous use of clothing body lice live and reproduce in clothing and only contact skin to feed, large recent clade suggests that humans began to wear clothing 72,000 years ago
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Flynn Effect
mean IQ has been steadily increasing in industrialized countries (even when corrected for culture- and generation-specific content) IQ has high heritability
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Correlations with Absolute Brain Size
as body, brain, and life-span increase: slowing of metabolism, maturation, reproduction, and even reaction time greater opportunity for trial and error and learning from others instinct may be less critical for survival
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Encephalization
measure of brain proportion that tries to "correct" for allometric effects not just brain/body ratio (which changes with size) measure of positive deviation with respect to the average brain/body size trend of other mammals primates deviate above the average trend for all mammals
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Encephalization: The Chihuahua Effect
small dog breeds can be as encephalized as primates (like chihuahuas) some are nearly as encephalized as humans but this does not necessarily make them more intelligent - they have been artificially bred for dwarfism or gigantism
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3 Mechanisms for Encephalization
1. post-cranial reduction = primate shift (two phases) -embryonic reduction of tissues comprising post-cranial body structures but not the brain in early embryogenesis 2. forebrain stem cell over-production = human shift -prolongation of brain growth phase 3. reduced postnatal body growth = dwarfism -regulated by growth hormone influences on the post-cranial body after major fetal brain growth phase Humans combine mechanisms 1 and 2
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neurons
information processing cells of the brain unique in many ways: 1. once produced they do not divide again 2. ionically polarized, highly reactive surfaces (maintained by ion pumps) 3. elaborate specialized input (dendrite) and output (axon) 4. axons contact other distant neurons or synapses, where release of neurotransmitters stimulates or inhibits that neuron's activity 5. require support cells (glia) to provide oxygen and glucose
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Grey and White Matter
gray matter - densely packed neuronal soma white matter - densely packed myelinated connections gray matter sheets are called cortex gray matter clumps are called nuclei or ganglia white matter forms into tracts of parallel axons
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Frequency "map"
spiral shaped cochlea is organized as tono-topic map hair cells in the cochlea create nerve impulses when they are "bent" by pressure waves spiral shape distributes different sound frequencies to different positions within it preserved in the auditory cortex of the temporal lobe
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Visual "maps"
projections from the retinas partially cross at the optic chiasm, sending information from the contralateral (opposite side) visual fields to opposite sides of the visual cortex retinotopic map organization is preserved, but so is the binocular visuotopic map
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Brain Development and Cell Death
more nerve cells die in the first two years than during the rest of life span over-production and selective elimination due to competition is analogous to natural selection prenatal loss of spinal motor neurons is extensive, but allows the brain to "adapt" to the body
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Sensitive/critical periods
transient period during which neural development is responsive to environmental input biased learning with a narrow maturational window - eg bird song or human language cued by species-typical "expected" developmental environments (eg imprinting)
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Imprinting
super-learning salmon hatch in streams, then migrate, only to return years later based on subtle odor cues they imprinted on ground-dwelling birds must learn to recognize their parent within hours of hatching and develop a strong attachment; follow their parent to find food and avoid predation
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Behaviorism
BF Skinner: the blank slate argued that behavior can be divided neatly into instinct and learning, and that all learning depended only on laws of association and reinforcement eg stimulus response learning paired with rewarding or aversive consequences = reinforcement assumed that environmental contingencies can explain all complex non-instinctual behaviors
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Sauce Bernaise phenomenon and John Garcia
taste aversions can be learned within a single trial if nausea is produced within a short time (super learning) --> even if the food did not cause the nausea John Garcia: easy associations between smell/taste and nausea, sight/sound with electric shock exemplifies predisposed learning biases
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John Garcia: evolved biases for learning
learning is not just dependent on density and structure of reinforcement learning biases are innate and affect how experiences influence the development of behavior effects of "nurture" are biased by "nature"
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supernormal stimuli
herring gull chicks get their parents to regurgitate food by pecking a red spot on their beaks unlearned behavior can be elicited by a red pencil herring gulls can be tricked if their eggs are replaced by quite divergent alternatives (giant egg)
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Rule: A mental capacity evolves only if...
...there is an evolutionary consequence parasitized birds are capable of distinguishing their own eggs from a cuckoo's eggs, but not that they are feeding cuckoo chicks this is b/c by that time it is too late to start a new nest and raise chicks to maturity possibility of a mistake, risk of abandoning slightly variant chick
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facilitated learning
eg oyster-catchers, which spend many months in the company of their parents to learn to feed safely and effectively on oysters (so as not to break their beaks) no specific oyster-opening instinct, but many attentional/behavioral/social biases that facilitate learning
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facilitated learning + language
similar to bird song early learning of language, well before ability to read or write "wild children" isolated in early childhood offer evidence of a critical period for language acquisition "motherese"
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non-human "communicative" behaviors
whenever Ally makes noise innate, automatic, unanalyzed, non-combinatorial linked directly to arousal state interpreted innately or spontaneously iconic (looks/sounds like) or indexical (predictably correlated with) what it signals
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language vs. innate emotional vocalizations
innate emotional vocalizations = laughter, sobbing, grains language is cortically controlled innate vocalizations are controlled by the limbic system
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aphasia
Broca's: disturbance of the ability to produce speech difficult word production, loss of fluency, telegraphic speech, difficulties with production and comprehension of syntax Wernicke's: disturbance of language comprehension errors of word comprehension and production without loss of fluency, some semantic confusion
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What makes language unique?
- requires the capacity to learn to articulate a wide range of oral sounds by mimicking others' speech sounds - uses a repertoire many orders of magnitude larger than than any other species (vocabulary) - uses combinatorial means to generate new meanings and references (grammar/syntax) - uses variant sound combinations to create meaningful words (duality of patterning) - differs in its way of referring to things (symbolic): allows reference to past, future, abstract objects
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laryngeal operation
attached to the hyoid bone and suspended from the base of the skull and the tip of the jaw vocal fold tension is controlled by the muscles that move 4 cartilages with respect to one another steps: 1. inter-arytenoid muscles rotate the paired arytenoid cartilages inward to bring the vocal folds together 2. muscles rock the thyroid cartilage forward on the cricoid cartilage to create vocal fold tension
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3 basic semiotic relationships
iKON: reference by likeness drawing, pantomime, camouflage, sculpture index: reference by physical-temporal correlation pointer, symptom, correlated feature, sample symbol: reference by conventional symptom only word, insignia, religious icon
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human larynx
positioned lower compared to other primates | allows a wider range of vocal sounds with less nasality
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obstetric dilemma
human babies are born immature (altricial) compared to most other mammals birth is far more traumatic for both mothers and newborns than most other species human brains have enlarged in hominid evolution the pelvis has narrowed/shortened to provide efficient bipedalism
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uniparous vs multiparous characteristics
uniparous: mostly have precocial babies and relatively easy births; humans are the rare exception multiparous: litter size correlates with shorter gestation and immature neonates
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effects of hominid evolution on birth
human birth is difficult, human babies are altricial advantages of maintaining human gestation length were sufficient to prevent earlier birth (despite maternal pelvic constraints) human brain growth continues at fetal rates after birth, meaning that human infants are born more altricial and demand more prolonged and extensive care than other primates
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summary of childbirth stuff
1. human fetal brain growth is typical for a mammal 2. human gestation length is typical for an ape 3. increase in brain size --> increase in altriciality
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menopause
few remaining mature follicles cannot produce enough estrogen and progesterone to maintain hormonal feedback to the hypothalamus and pituitary leads to hormonal dysregulation and loss of remaining immature oocytes
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why menopause?
we age slower than our body size predicts --> suggests that menopause arose as a side-effect of extended lifespan for our body size not an adaptation
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possible aging mechanisms
``` evidence for damage theories: -basal metabolism (rate of living) -body size correlation -oxidative damage -telomere deletion/repair evidence for evolved obsolescence: -comparative reproductive trade-offs -iteroparity/semelparity differences -predation rate and arboreality effects -disposable soma theory -pleiotropic partitioning ```
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steroid hormones
regulate gene expression both water and fat soluble, pass easily through cell membranes, bind to receptor molecules in target cells, which modifies gene expression and protein synthesis hormones are synthesized from cholesterol and each other
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one control system: two sexes
male and female gonadal axes are regulated by the same hypothalamic and pituitary hormones LH and FSH perform homologous functions with respect to hormone production and gamete maturation in the two sexes
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sexual differentiation of the external genitals
male and female external genitalia are also formed from a common substrate testosterone and its metabolites differentiate the male, by closing the ano-genital opening to make penis and scrotum female form is the "default" pattern and does not require hormonal intervention to develop
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sex chromosome disjunction errors
Kleinfeldter's Syndrome: XXY karyotype, male hormones until puberty when breasts enlarge (gender identity is male) Turner's Syndrome: X0 karyotype, female genitalia but some physical abnormalities (gender identity is female) Androgen insensitivity syndrome: XY chromosomal male with faulty testosterone receptor, feminized external genitalia (gender identity mostly female)
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4 idependently modifiable dimensions of gender-specific behavior
1. attachment - affiliative-nurturant vs aggressive-detached 2. sexual partnering/male choice - long-term reluctant vs variety-promiscuous - status attributes vs physical attributes 3. erotic target - male vs female physique 4. self image - male vs female physique
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atypical "life history" in humans
``` life history = typical sequence and schedule of maturational/senescence events human heterochrony: immature birth prolonged brain maturation prolonged childhood adolescence post reproductive life extension ```
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adolescence as a bio-social creation
with industrialization, there has been a significant decline in the age of sexual maturity in both sexes and a significant postponement of marriage and first conception in pre-industrialized societies, marriage is generally close to the age of sexual maturity --> social consequence of spending nearly a decade of life sexually mature but societally prevented from reproducing?
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self-domestication of humans
domestication = relaxation of selection on a number of critical physiological, emotional, and cognitive adaptations 1. possibility of language depends on a loss of innate biases rather than introduction of an innate language faculty 2. novel artificial niche - resulting in unprecedented natural selection on mental functions 3. produces changes in brain size, regional proportions, and connection patterns to adapt to these special demands
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finch analogues in language
1. both have lost the link with specific emotional states 2. equalization of transition biases from sound to sound 3. increased influence of auditory learning for vocalization 4. many more widely distributed forebrain structures were recruited and function synergistically 5. vocal repertoire largely determined by social transmission 6. innate call features are still used to express emotion as speech prosody
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mutually exclusive mnemonic mechanisms
procedural memory - frontal-striatal-cerebellar circuit creates memory traces for skilled action by constant repetition and fine tuning episodic memory - sensory-hippocampal circuit creates memory traces for singular experiences by correlations between features language: source of a new synergistic form of memory (narrative memory)h
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humans' symbolic "savant" syndrome
we compulsively expect to interpret things symbolically symbolic reframing of iconism uniquely human emotions, result of dissonant icons
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niche construction
short-circuit of natural selection beavers modified their ecosystem so that beaver bodies have had to adapt to the aquatic niche created by beaver activity symbolic niche evolution
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dual inheritance theories
refers to the parallel transmission of information and influence both by genetic and by communication-learning mechanisms two forms of inheritance aren't symmetric b/c the ability to transmit and acquire non-genetic information is a consequence of evolved capacities form and content of the communication and biases of the learning processes that support socio-cultural-technological transmission will tend to be influenced by evolved psychological biases
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maladaptation
modern environments diverging from the human EEA | EEA = environment of evolutionary adaptation
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causes of maladaptation
1. selection conditions change eg agriculture, industry, migration 2. causality is not understood, or hard to discover eg Kuru, colostrum denial, birth control 3. elites (empowered individuals) manipulate others eg war, religious sacrifice, status polygyny 4. costs of exploitation accumulate over time eg ecological over-exploitation, global warming
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Kuru
a prion disease prions = proteins related to naturally occurring brain proteins bind to these normal proteins and change their shape (conformation) these then become prions, which are not broken down, accumulate in the brain, cause neuron death cultural enhancement of prion propagation = cannibalism
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colostrum "pre-milk"
thick yellowish liquid that has little protein, fat, or milk sugar primary breast "milk" for the first days afterbirth fills breast alveoli prior to birth rich in igG antibodies - may have evolved to protect the alveoli from infection ingestion by neonate protects the infant from intestinal bacteria, etc. withheld from some newborns in some cultures as bad milk --> hard to link to infant mortality
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demographic transition
how technology fools biology increased female education and autonomy, increased education generally --> reduced birth rates, later marriage, upward shift in age pyramid increased localized population densities = increased interdependence among strangers increased communication and information sharing --> decreased personal violence and decreased tolerance for accepting inequality and suffering --> predictive science and increased potential for innovation
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Final Summary
1. humans have inherited evolved learning biases, social emotions, and behavior tendencies relevant to a past EEA 2. these "expect" and depend on certain environmental inputs for normal development 3. we have been evolving for over 2 million years in an artifically constructed niche of symbols and tools 4. this forms a parallel inheritance process that has its own evolutionary logic that is still poorly understood 5. human psychological adaptations have co-evolved with this artificial niche and our brains "expect" this culturally transmitted information to inform normal brain development 6. this dependency has produced a kind of self-domestication that has produced considerable flexibility of behavior 7. industrialization has produced an environment very different from our EEA (more maladaptation) 8. knowledge and communication can "fool" our evolved tendencies into producing maladaptation (not all of which is bad)