Midterm 2 Flashcards
Why Study Primates
primate understanding explains our own behaviour
Linnó
first major biologist to insist that humans are primates
Richard Owen
last major biologist to insist not primates (darwin’s rival)
hippocampuses are different (or so he thought)
Thomas Huxley
proves Owen wrong - primates do have a hippocampus minor
Why Study Primates?
We are primates
reasoning by analogy
how does evolution shape behaviour?
Characteristics of primates
vision rather than smell
big brains
generalized dentition
manual dexterity
opposable thumbs, nails v claws
increased life spans + slower development
social
petrosaol bulla (not in fossils)
Where do Primates Live?
Africa, Asia, South/Central America
tropical regions + forests
fossils all over the world
gregarious
sociable
philopatry
which sex remains in group its born into
group structures
solitary, pair-bonded, one-male unit, polyandry (1 female), multi-male/multi-female, fission-fusion (flexible in group pattern)
activity patterns
nocturnal, diurnal, cathemeral (dawn + dusk)
food groups
frugivore, folivore, insectivore, gumivore, omnivore
tooth structure of primates
incisors, canines, premolars, molars
primate groups
lemurs & lorises, tarsiers, new world monkeys, old world monkey, apes
strepsirhine (lemers & lorises), haplorini (everything else)
catarrhine (old world monekys + apes)
prosimians (lemurs + lorises, tarsiers) & anthropoidea (monkeys + apes)
Lemurs & Lorrises
lemurs: madagascar
lorrises: tropical Africa and Asia
primitive features
longer snouts, wet curved nose, no color vision, tooth comb
tapetum lucidum: relective layer behind retina (indicate that early = nocturnal), long hind legs (leap)
no bone behind eyes
Lemurs
nocturnal or diurnal
solitary & gregarious
arboreal & terrestrial
mainly frugivorous
Lorises & Galagos
nocturnal
solitary
arboreal
fruit, gum, insects
Haplorhines
tarsiers, old + new world monkeys, apes
orbital closure, dry simple noses, no tapetum luitum, color vision, cascularization of brain and placenta
Tarsiers
nocturnal, arboreal, many similarities with lorises (prosimians)
carnivorous
big hind limbs for leaping
New World Monkeys
2 families: Cebidae and Pithelicida
Ceibidae subfamilies: Atelinae, Aotinae, Callitrichinae, Cebinae, Samirinae
diurnal (except for owl monkey)
arboreal
social system and diet vary – small: pair-bonded and gumivores; large: multi-male/multi-female and frugivores/folivores
amrs + legs same length
tail moves independently
ex: spider monkey, pygmy marmoset, red vakari
Catarrhine
Old World Monkey + Apes
all diurnal
arboreal + terrestrial
vary in social + diet
different in ways skulls fuse and dental formulas
Old World Monkeys
colobine (leaf eating) or cercopithicine
Colobines
branch of Old World Monkey
sacculated stomach, reduced thumbs
arboreal and folivores
babies diff color than adults
Colobus (Africa), lay monkey, proboscis monkey
Cercopithecines (cheek pouch monkey)
part of old work monkeys
diet + social systems vary
arboreal and terrestrial
female philopatry, strong F-F bond
macaques (snow monkeys) + baboons
Hominoidea (Apes)
Gibbons, Orangutans, Gorilla, Chimps, Humans
gregarious (except Orangutan)
mostly frugivores (except Gorillas)
arboreal + terrestrial
high diversity of social systems
Morphology
old world monkey: narrow, deep ribcage, scapula on side
ape: broad, shallow, scapula on back of the rib, long arms, short legs
Primate Diet
teeth well adapted to deits
body size adapt to diet (small = small amount of high quality food, larger: large amounts of low quality food)
basal metabolic rate does not scale 1:1
Sexual Selection
explains evolution of armaments and ornaments
Armaments
weapon-like structures that males have
Ornaments
showy structures - appear beautiful
secondary sexual characteristics
traits that funciton in reproduction but are not necessary
darwin’s theory of sexual selection
reduced survivorship of males w/ structure - compensated by advantage in reproductive success
intrasexual selection
male-male
intersexual selection
male-female
bateman principle
male reproductive success increases when partners increase
female reproductive success stays constant
provisioning
more food leads to bigger populations (instead of obesity, more babies)
food enhanced baboons
increase maturity and shorter inter birth intervals
age at gestation
young: still growing, higher mortality, lack experience
older: senescence, death
Dominance Rank Influence on Reproduction
higher social dominance – higher reproductive success
eat better - contest competition
earlier age at first rep, shorter IBC, higher infant survival, higher survival during epidemics
higher quality of infants (alpha male sons)
differ in small vs big groups - scramble competition
contest competition
higher rank eats/wins more
scramble competition
more competition in large groups due to shared resources
Sociality and Reproductive Success
F-F bonds promote reproductive success (infants more likely to survive)
ex: Okavango baboons - 50% more likely to survive
Female Trade-Offs in Reproduction
limited resources (allocation of energy to 1 at expense of others)
quantity v quality of offspring
weaning: time varies - infant needs to forage on own
Male Reproductive Strategies
sexual dimorphism
rank
sneaky copulation
behavioural flexibility
sperm competition
sperm plug
bacculum
sexual dimorphism
males are bigger and more agressive
compete for access to females
pair bonds –> little male-male comp –> little dimorphism
one-male/multi-female & multi-male/multi-female –> large dimorphism
sneaky copulation
lower ranking male copulates behind higher ranking male’s back
behavioral flexibility
in one-male units, can be more than one male if territory is hard to defend
male munquis - peaceful and no dominance - what???
sperm competition
sperm competes to reach egg
morphological: testes size; in one male, small, in multi-male, large
multi-male species have faster sperm swimming speeds
sperm plug
gelatinous proteins create plug at the end of an ejaculation
blocks other sperm from reaching eggs
prevent sperm competition
bacculum
penis-bone
dislodge sperm plugs and lengthen copulation duration
pair-bonding parental investment
increased investments, although extrapair copulation is common (mate-guarding=/= monogomy)
both invest and watch in offspring
titi+owl monkeys, marmosets, tomourins, gibbons, humans
cooperative breeding
males + other individuals help to raise young
marmosets + tamorins: obligate twinners - increase RS w/ help; humans
infanticide
not pathological!
when change in male residence/status (ex: change in male in one-male/multi-female units), results in resumption of female cycling
naturalistic fallacy: expanations do not equal justifications
Female Counterstrategies to Infanticide
paternity confusion
friendships
bruce effect
paternitiy confusion
Female Counterstrategies to Infanticide
swelling persists for 10 days (more than ovulation period)
copulate w/ many males - don’t know who the father is
friendships w/ males
Female Counterstrategies to Infanticide
male protect female, female grooms male
less corisol spike after new male takeover
babies feel safe w/ mom’s friends
bruce effect
Female Counterstrategies to Infanticide
female geladas
spontaneous aboriton after new infanticidal male takes over group
ornaments
are they evident of mate selection?
females are more likely to approach males w/ ornaments
ornaments associated with rank and agression
may serve as signal in male-male competition instead
benefits & costs to living in groups
benefits: vigilance, food, raise offspring
costs: visibility, competition, disease
primates as prey
common predators: raptors, felids, snakes
chimpanzees: predators of monkeys
benefits of groups against predators
more organisims - dilution
vigilance (can see)
active defense (can mob)
predation risk + group size
high risk + many predators – large groups
high risk – higher M to F ration
troops
predictable membership, always together
fision-fusion
predictable community membership, unpredictable party membership
socioecological model to group size
females form groups with kin to defend clumped, high quality food
females disperse from kin when food evenly distributed to avoid competition
wrangham 1980
gibbons socioecology
food in small patches (1 female)
1 male can only actively defend 1 female
result in small, pair-bonded, well defended territories
social monogamy, no philopatry
savannah bonobos socioecology
females defend group of high quality food
males come to defend whole group
multi-female/multi-male
polygamy, female philopatry
orangutans socioecology
food in small, densely distributed patches (1 female per)
1 male overlap several females (high sexual dimorphism)
uni-male polygamy, solitary female, no philopatry, no bonds
almost no food is available
gorillas socioecology
low quality, evenly dispersed food
female wander, not-constrained w/ low feeding competition
males wander and females group around to protect
high sexual dimorphism
no philopatry, weak F-F bonds, social unimale polygamy, one male unit
chimps socioecology
small, sparsely distributed patches - 1 female per patch
males cooperate to defend many females
multi-male polygamy, solitary females, male philopatry, strong M-M bonds
social org: never all together at one time (reduce scramble comp); males mroe social than females
females mate with all males, males form strong bonds but have strong competitions
bonobos socioecology
more food in habitat - females stay in parties together
strong F-F bonds, though unrelated
F-F bonds curb agression - coalitions dominant to single male
cooperation
act in manner than benefits others - costly
cheating is better strategy
why altruism?
altruism
altruism doesn’t help reproduction
coalition formation, food sharing, allo-maternal care, territorial defense, alarm call
how does altruism evolve?
assortment with other altruists
if with kin, larger chance of them having gene to be altruist
if they group together and the non-altruists die, the frequency of altruists increase
hamilton’s rule
altruism limited to other altruists
share genes through kin - likely help those that share this gene
altruism is favored by kin selection when benefits * relatedness >cost to altruist
if kin, also supports inclusive fitness (inclusive fitness theory)
kinship benefits
grooming is most likely between mother and infant
coalitions mostly with kin
social bonds are strengthened by kinship
in male philopatric socieites, males more cooperative
cooperative breeding: helpers + defense
familiarity
recognizing kinship
mothers don’t recognize own infants at birth - familiarity is important
when mother + infants stay together, form familiar bonds with siblings
age-proximity
recognizing kinship
in one-male units, age proximity tied to paternity
facial cues
recognizing kinship
can recognize shared features
non-kin cooperation
prisoner’s dilemma - why choose instance that could be really detrimental?
prove trustworthiness
reciprocity
reciprocal altruism
cooperate if parter cooperated before
immediate cost payed back later
cost to donor < benefit to recipient
opportunity for role reversal (not in despotic societities)
captive studies: once a chimp/tamarin knows that one is not cooperative, will not pick them
evidence: grooming (NOT: vampire bats, male coalitions)
life history
description of key events in an individuals life cycle
growth, development, reproduction, death
life history theory
energy is allocated to growth, maintenance, and reproduction
trade off in quality and quantity of offspring
correlated traits w/fast + slow reproduction
fast: reproduce early, small body, small brain, short gestation, large litters, high mortality, short life span
slow: reproduce late, large body, large brain, long gestation, small litters, low mortality, long life spans
fixed energy model
can grow or reproduce, not both
wait too long - may die before reproducing (extrinsic mortality = disease, predation, starvation) - high chance of death–> early reproduction favored
delay maturity + wait: improves offspring survival
primate life cycles
slow maturation (grow HUGE brain)
low extrinsic mortality
Senescence
why do we grow old and die?
energy allocated towards growth + fertility @ expense of longevity
allele for late death not removed by natural selection - passed on
Antagonistic Pleiotropy
pleiotropy affects genes that favor early fertility
ex: testosterone - positive effects on fitness at early ages, link to prostate cancer and heart disease
Mortality: Chimps v Hunter-Gatherers
human hunter-gatherers live longer than chimps - stay alive post reproduction
why? Grandmother hypothesis
Grandmother Hypothesis
evolutionary benefit to living post-menopause
invest in grandkids
Hadza: contribute substatially to food (shared w/ children + grandchildren - more likely to survive and pass on gene)
presence of mother: reduce age at first birth and increase survival of first borns
longevity of male: by products
Need to Learn Hypothesis
brain size because social and ecological complexity takes a long time to learn
lot of time and energy to grow such a big brain
(chimps recognize numbers in order, macaques wash food)
Brain Structure
hindbrain (cerebellum & brain stem)
midbrain
forebrain or cerebrum (4 lobes - occipital, frontal, temporal, parietal, neo cortex)
folding: more surface area for neocortex
Intelligence & Brain Size
brain size inconsistently related to IQ
relative brain size doesn;t account for selection on body size
relative neocortex size/executive brain ration
neocortex/whole brain
cognitive ability & reversal learning correlates
*relationship dependent on how you measure the brain
constraints on brain
expensive (never stops using calories)
expensive tissue hypothesis
tradeoff expensive tissues in brain with expensive tissues in gut
primates with better diets & smaller guts –> bigger brains
Social Brain Hypothesis
not a lot of support!
large brains to navigate social arms race
other tools are just by products
prediction: bigger social groups –> bigger brains
only works if seperate apes and monkeys
Ecological Brain Hypothesis
some types of foraging are more cognitively demanding than others
for given body sizes, frugivores have bigger brains than folivores
ex: apes have biggest brains and most sophisticated foraging techniques
Behavioral Flexibility Hypothesis
learn new solutions to problems from others
cope w/ ecological and social challenges
selected for flexibility and problem solving
correlation between relative neocortex size and innovation + social learning
Cognition
refers to process of information and application of knowledge
ex: chimps can recognize themselves in a mirror (great ape specialty)
Theory of Mind
can understand what others think
humans develop after the age of 4
macaques + chimps can infer obvious human behavior
subordinate more likely to stay back when dominant knkows where the food is
primates have basic theory of mind
Social Cognition: Humans vs Apes
2yo and apes - same test
same physically
