Anthropology Chapter 3

Slides: Primate Habitats and sociality

Studying behavior

-Proximate — How did it develop

-Ultimate — Why did it evolve

Mating Systems

Monogamy - Breeding (1 male:1 female)

Polygyny - Breeding (1 male: multifemale)

Polyandry - Breeding (multimale: 1 female)

Polygyandry - Breeding (multimale: multifemale)

Social Systems

Solitary/semi-solitary

One male units

Multimale/multifemale group

One female, multimale units

Fission-fussion groups - Groups always changing in size and composition

Fission-fussion determinants

-Resources

-Leadership ability

-Species density

-Predation risks

Who takes care of babies

-Mostly mothers

-Sometimes males significantly help

-Sometimes other females

Who’s in charge

-Alpha males

-Alpha/mother female

*Baboon Social Rank

*Marmosets and tamarins

-Both/unknown

Foraging Theories

-Optimal foraging theory and Marginal Value Theorem

-Geometric Framework of Nutrition

Optimal Foraging Theory

• Maximizing intake of energy or nutrient/time
• Energy or nutrient = currency
• Other needs = constraint

• Useful and testable

Optimal Foraging Theory Criticisms

• Too simplistic

• Dynamic nature of food and nutrient interactions unaccounted for

• Constraints are not viewed as critical parts of model

Optimal Foraging Theory: Marginal Value Theorem

Leaving the space when the food supply is lower than average. The linger you spend in a place, the less consumption

MVT is not supported in…

• Meta-analysis

• Orangutans

• Gibbons

Geometric Framework of Nutrition

Seeking nutrients that you need.

Capital Breeders

-Organisms that build up
energy reserves prior to
breeding, then reproduce

Income Breeders

-Organisms that rely on
energy intake during
breeding season for
reproduction

Energy and Ovulation in Humans

Human female bodies automatically
regulate ovulation so that as the
energy levels decrease, the likelihood
of pregnancy decreases all the way to
anovulation and cessation of cycling

Theoretical Backgrounds

-Socioecological model

-Evolutionary Model

-Sexual Selection

Male Reproductive Competition

Sperm competition male chimpanzees

Female Reproductive Competition

When the females become more aggressive towards each other.

Ex: Gorillas – Females mate during pregnancy, mate more on days when
other females are mating

Primate Sexuality

Sexuality is situationally dependent

Ex: Female langurs solicit invading males even
though already pregnant (to confuse
paternity),

Bonobo sexuality

Not procreative sexual activity always

Estrus Swelling

• Attraction of many males
• Inciting competition -> best mate
• Confuses Paternity
• Infanticide avoidance strategy
• Allowing female transfer between groups