ANTH 1200 Human Origins
Exam 2 review sheet – Part 2
Primate Social behavior
• Primate Socioecology
• Socioecology: how ecology affects (social) behavior
• access to food and predator avoidanceà living in social groupsà
competition/conflict, cooperation, social complexityà social system
• Reproductive Strategies
*Male and female reproductive strategies differ
o Both males and females seek to maximize reproductive success (RS)
o Females always provide care for young
o Male parental care is absent/limited
• Reproductive Strategies: Females
§ Female RS limited mainly by food resources
o energy for pregnancy and lactation
o greater investment in offspring
o well-nourished females and higher infant survival = higher RS
§ Female strategies:
o maximize access to food resources
o mate choice
• Reproductive Strategies: Males
§ Male RS limited mainly by females
o not much energy needed to reproduce
o less investment in offspring rearing
o more females (mating) and more offspring = higher RS
§ Male strategies:
o maximize access to females
o mate competition
• Social and Mating systems
• *Social system = type of group in which primates live
• Three main components of primate social systems
o Social organization
o Mating system
o Social structure
• Social system: social structure + social organization
§ Social organization: group size and age and sex composition
§ Social structure: patterns of social interactions and resulting relationships
• Mating system: typical number of males and number of females within each group that
mate and reproduce
§ Monogamy: one male-one female
§ Polygyny: one male-multiple females
§ Polyandry: multiple males-one female
§ Polygynandry: multiple males-multiple females
• Sexual Selection
§ Male competition and Female choice
§ Sexual dimorphism: Difference between male and female in body size, shape,
color
§ Sexual Selection due to Male Mate Competition leads to
o larger body size
o larger canines
§ Polygynous and polygamousàmore sexual dimorphism
§ Monogamous and polyandrousàless/no sexual dimorphism
• Infanticide
§ Sexually selected male reproductive strategy
§ Speeds up female resumption of cycling
§ Changes in male residence or hierarchy
§ Female counter-strategies:
• paternity confusion (females mate with multiple males)
• lactating females form “friendships” with males
• Social systems
o Solitary
§ 1 adult female + dependent offspring in individual territories
§ Male range overlaps territories of few females
§ Mating system: Polygynous
• lorises
• galagos
• tarsiers
• some lemurs
• orangutans
o Pair Bonded
§ 1 adult male + 1 adult female
§ Mating system: Monogamous
§ Paternal care of infants
§ Paternity certainty for males
§ BUT extra-pair copulation
• titi monkeys
• owl monkeys
• some callitrichids
• gibbons and siamangs
o Cooperative Breeding
§ 1 adult female + >1 adult males
§ Mating system: Polyandrous
§ Male care of infants
§ Reproductive suppression of subordinate females
• marmosets
• tamarins
o One-Male Multi-female Groups
§ 1 adult male + >1 adult females
§ Mating system: Polygynous
§ All-male “bachelor” groups, solitary males
§ Takeovers
§ Infanticide
§ Male influx during breeding season
• some lemurs
• most colobine monkeys
• guenons
• gorillas
• howler monkeys
o Multi-male Multi-female Groups
§ >1 adult males + >1 adult females
§ Mating system: Polygamous
§ Dominance hierarchy for males
§ Male competition: alpha male has priority of access to estrous females
• macaques
• most baboons
• capuchins
• some lemurs
o Fission-Fusion
§ Less cohesive social groups
§ Mating system: Polygamous
§ Communities split up into temporary foraging parties
§ Male coalitions
§ Species eating clumped resources
• spider monkeys
• chimpanzees
• bonobos
o Multi-Level Social System
§ Multiple levels of organization
§ Mating system: Polygynous
§ Solitary males
§ Takeovers
§ Infanticide
• hamadryas
• geladas
• snub-nosed monkeys
o Socioecological ModelàResource DistributionàFemale Distributionà Male
Distribution à Social System
o Females are often organized into groups of related females who cooperate with
one another and compete with other groups for food resources
o Males then distribute themselves according to where the females are and how
many females they can defend from other males
Primate Conservation
• Threats to primates
o Habitat loss
§ Example:
§ Oil palm plantations
§ Indonesia and Malaysia
§ Slash and burn agriculture
§ Major threat to orangutans
o Deforestation: agriculture, logging and wood harvesting, cattle ranching,
roads, drilling, mining
o habitat fragmentation
o habitat degradation
o forest fires
o human-wildlife conflict
o Hunting
o Bushmeat
§ Subsistence and commercial hunting
§ Africa and South America
§ Effects on other species and forest ecology
§ Imported into non-habitat countries
o Traditional medicine
o Traditional folk practices
o Accessories and jewelry from monkey skins, bones and teeth
o Crop pests
o Live capture (Pet trade)
§ High demand for infants
§ Lactating mothers killed
§ Death and injury while trapping
o Export of animals for biomedical and pharmaceutical research
§ Late 1960s and 1970s:
§ Rhesus macaques in India (50,000/year)
§ development and testing of polio vaccine
o Climate change
o Global warming, increasing CO2, extreme weather, altered habitats
§ Effects on
§ Plant phenology: fruiting/leafing patterns, seasonality, nutritional
value à primate diets
§ Primate ranging
§ Primate reproduction
o Disease: Increased contact between humans and primatesà increased possibility of
sharing infectious diseases
• Solutions
o Protected areas
§ National parks, nature reserves, wilderness areas etc.
§ No development
§ Prevents hunting and poaching (in theory)
o Community-based conservation and education
§ Biological conservation and human development
§ Engaging and benefiting local communities
§ Education of local communities
o Ecotourism
§ Revenues à local economy + conservation
§ Issues:
o habituation of animals
o disease transmission
o pollution, habitat degradation, unethical practices
o Captive breeding
§ Reintroduction
o establishing a new population where the species previously existed but
has since disappeared
§ Restocking
o supplementing an existing population to increase its size
§ Issues:
o reproduction and survival in captivity may be limited
o costly
o reintroduction is difficult
§ Variable success
o e.g. golden lion tamarins in Brazil
