Title: Week 8: Primate Social Behavior
1Week 8 Primate Social Behavior
2Sociality
- Why be social?
- Social living involves costs
- Competition for all resources
- Intra-group violence (including infanticide)
- Disease transmission
- What are the benefits?
- Two reasons (Alexander)
- To avoid predation
- Safety in numbers (tend to form large groups)
- Harder to feed everyone
- Common resources capture
- Social hunters (tend to be small)
- Diminishing return problem
- Collective defense of territory or competition
with other groups - Balance of power
3Types of Primate Social Groups
Solitary Orangutans
Polygyny one-male Gorillas
Monogamous Gibbons
Polygyny multimale Chimps
Polyandrous Tamarinds
4(No Transcript)
5Brain to Body Weight Across Species
6Food or Social Interactions?
7Getting Enough to Eat
- Larger animals need more food overall
- Smaller animals need proportionally more calories.
8Nutrients and Toxins
- Primates have diverse diets
- Different primates eat different combinations of
foods - Need a good source of protein and a good source
of carbohydrates (sugars)
9Body Size and Diet are Related
10Different Diets have Different Adaptive Problems
11Eating, Traveling Resting
12Territories vs. Ranges
Territories are not overlapping, boundaries are
defended
Ranges are overlapping, not exclusive
13Predation
- Smaller primate more likely to be victims of
predators - Higher predation may lead to larger primates and
a shift in food - Effects choice of where you live
- Different defense mechanisms
- Shelters
- Activity patterns (diurnal, nocturnal)
- Warning calls
- Form of cooperation (Kin selection/Inclusive
Fitness - Multi species cooperation (Reciprocal Altruism)
- Different calls for different predators
14Resource Competition and Dispersal Patterns
- Resources are patchy and limited
- Greater competition and dominance hierarchies
- Within group competition greater than between
group - Females will form kin based coalitions
- Females will form dominance hierarchies
- Female philopatry Matrilocal
- Between group competition gt within group
competition - Females will be more egalitarian
- Females will still favor kin and be philopatric
15- Both within and between group competition is
strong - Combination of the previous two contexts
- Females favor kin groups philopatric
- Females more egalitarian
- When resources are dispersed you get scramble
competition - Females have little motivation to form dominance
hierarchies - Females have little reason to form coalitions or
be philopatric - Rare?
- Where are the males?
- Males go where the unrelated females are.
- If females are philopatric then males must leave
their natal group to avoid inbreeding depression. - The more females in a group the more they become
a defendable (patchy) reproductive resource for
males - The more females in a group the harder for one
male to monopolize them, especially if they have
asynchronous estrus.
16How do Chimps and Humans Fit in all of this?
- Not very well!
- Male philopatry Patrilocal (even Bonobos)
- The socioecological models presented in you book
would lead you to believe that Chimps and our
common ancestor live in a scramble competition
context, but they dont, and they are
territorial. - Other possibilities?
- Wrangham and Madson argue that
- Chimps and Human males will be territorial if
resources are defendable (patchy) and important
to females - If resources are not defendable, males will fight
over females
17Cost of Grouping Hypothesis (Wrangham)
- Males have an advantage in the cost of grouping
- Males can forage farther for the same energy
costs (more efficient) because they are caring
babies or the extra weight of pregnancy (women
paying a higher cost for reproduction) - You can put more males in a given area (fixed
amount of food) than you can put females - Because of the lower cost of grouping men form
larger groups than males. - They use there larger coalitions to compete with
other groups of males, but also to dominate
females.
18What about Bonobos?
- Bonobos dont compete with gorillas for food
- More food to eat
- The cost of grouping goes down for males and
females - Females are not longer disadvantaged in terms of
the cost of grouping - Females are better at forming coalitions (through
sex) despite male philopatry (Patrilocallity) - Females dominate Males
19Evolution of Culture
- Culture is about learning
- Cultural behaviors that are not innate
- Acquired in a social context
- Is culture unique to humans?
- NO
- Unique to Apes?
- NO but rare
- Social facilitation vs. Observational learning
- Monkeys dont ape
20Adaptations for Observational Learning led to
- The ability of innovations to spread through a
population without having to evolve new
adaptations. - Individuals not having to start from scratch,
they could build on the knowledge and skill of
others - Cultural explosion
- Homo Erectus tools (choppers) were vary useful
but did not change. - With Modern Humans there was something equivalent
to adaptive radiation with behaviors (tools, art,
subsistence practices, etc.,) - New Data indicate that Observational learning has
special features - Joint attention
- Functional understanding of cause and effect.