Ch 7 Primate Behaviour Flashcards
Behavioural Ecology
“The way an animal adapts behaviourally to their environment”
• Behavioural similarities represent millions of years of evolution (natural selection)
• Genetic drift, founders’ effect… could be related to any of these, most related to natural selection
Homoplasy vs. homology
Homoplasy – similarity due to convergent evolution (derived)
Homology – similarity due to evolutionary descent (ancestral)
First Primate Studies:
Free ranging, field studies, lab studies
17th Century – anatomy of captive primates
Colonies of free-ranging primates
Field studies began 1960s/70s
Laboratory experimental studies began 1950s/60s
Behavioural Genetics
- Study of how genes affect behaviour
- Behaviour must be viewed as a complex interaction between genetic and environmental factors
- Primates have very high capacity for behavioural flexibility
Factors Influencing Social Living:
Diet, body size, BMR
Diet
- Large animals that don’t need energy dense foods can eat almost anything, so they don’t expend much energy looking for food, because it’s everywhere
Body Size
- Small mammals need to eat more than large mammals per unit of weight
Basal Metabolic Rate (BMR)
- Smaller animals have a higher BMR
- Smaller animals require an energy-rich diet (insects, fruits, seeds; NOT leaves)
Factors Influencing Social Living:
Resources, predation
Distribution of Resources
- Abundance vs. scarcity; dense vs. spread-out; clumping, seasonality
Predation
- Smaller animals can be prey for snakes, leopards, wild dogs and other primates
Factors Influencing Social Living:
Dispersal
- Members of one sex leave the group upon sexual maturity
- Male dispersal most common, many with female dispersal, some species with both
- Minimizes conflict and inbreeding
Factors Influencing Social Living:
Life history
- Characteristics of developmental stages
- Identify the species and influence reproductive rates
Ex. Length of gestation, length of interbirth interval, age of weaning, age of sexual maturity, life expectancy
Factors Influencing Social Living:
Activity Patterns, human activities
Activity Patterns
- Diurnal vs. nocturnal
Human Activities
- Most populations are now imp acted by human hunting and forest clearing
- Disrupt, isolate groups, reduce numbers, reduce resources, cause extinction
Social Living:
Advantages
- Maximize food exploitation
- Sharing information and defending food sites
- Improved reproductive fitness (more partners available)
- *Protection from predators
- Help in caring for offspring
- Transmission of knowledge/ behaviours
Social Living:
Disadvantages
- Increased conflict, greater aggression
- Increased competition for food
- Increased competition for mates (can result in lower birth rates)
- Larger groups more likely to spread infectious disease
Dominance Hierarchies
- Rank determined by competition (strength, aggression, alliances)
- Sometimes parental rank
- More common in multi-male/multi-female groups
- Provide social stability and reduce conflict
- Higher ranked females often have higher infant survival rates and decreased inter- birth intervals
Language and Communications
1) Visual (body position, facial expression)
2) Auditory (vocal)
3) Olfactory
4) Tactile (grooming)
Purposes of communication in primates
- Mark territories
- Warn of predators
- Convey interest in mating
- Draw attention to food resource
- Threaten or avoid aggression
- Reconcile with former opponent
Do NHP really possess language
In the 1960s sign language studies began
- Understand the symbol (ex. blueberry) but does not have grammar and syntax (does not know what a blueberry is)
By this definition they do not have language
Agnostic Behaviours
Acts of aggression common
- Threatening facial expressions/gestures
Ex. Baring canine teeth, chest thumping
- Physical fighting
- Male aggression more often brief & face-to-face
- Female aggression more often prolonged & indirect
- Documented in chimpanzees, bonobos, orangutans, baboons
- Rare in gorillas
Affiliative Behaviours:
Alliances
- Evolved indirectly through kin selection
- Tendency to direct beneficial behaviour toward biological relatives in same social group
- Indirect way to pass along genes
Ex. Getting access to food, sex, protection, hunting parties, territorial defence
Affiliative Behaviours:
Grooming and Physical contact
- Grooming reduces stress, reinforces social bonds, curries favours for food, sex, protection
- Lowers cortisol levels (reduces stress)
- Can occur between males and females, relatives, strangers
- Frequency and duration depend on many actors
Affiliative Behaviours:
Reconciliation
- Common in groups with a lot of agonistic behaviours
- ‘Make-up’ and ‘move-on’ Debates about empathy & altruism
- Taking our ideas and applying them to these behaviours (anthropomorphism)
K vs. R selection
- Primates are K – produce few young and invest a lot of energy
- Burden carried by the female
- Length of reproductive cycles
• Interbirth intervals
• The more males help, the more the interbirth interval decreases
Sexual Strategies:
Female
Choose ‘most fit’ and ‘quality’ male
Because higher degree of parental investment
- Choose dominant, or affiliative males
- Mate with multiple and unfamiliar males
Sexual Strategies:
Male
As many females as possible ‘quantity’
- Because lower degree of parental investment
Results in male-male competition
- Larger body & canine size, ‘flashy adornments’
- Dominance rank, ability to coerce females
- Causes sexual dimorphism
Sexual Strategies:
Male- Infanticide
- Killed young offspring that might not have been theirs, the offspring remaining who were born could have been their offspring
- Collected genes to test this, and yes it showed that the Alpha male may have more reproductive success
Sexual Strategies:
Polygynous Groups vs. Multimale/female groups
Polygynous groups
- Alpha male spends a lot of time and energy actively excluding other adult males
Multimale/Multifemale groups
- Males usually compete in the presence of estrous females, within dominance hierarchy
- *Dominance rank not always associated with higher reproductive success
Sexual Strategies:
Bonobos
Hetero and homosexual behaviour - Between related and unrelated individuals - Humans and bonobos only species to have regular face-to-face sex Many purposes beyond reproduction - Facilitate female group transfer - Reinforce social bonds - Reduce tension - Establish power alliances
Do non-human primates have culture?
Culture
- Things that are learned, shared and socially transmitted within a society and across generations
- Most biological anthropologists say yes
Tool use:
Chimpanzees
- Twigs to extract termites
- Hammerstones to crack
- Sticks to dig for tubers, roots, bulbs
- Fashion spears from twigs to hunt bush babies
- Use different tools to get at subterranean vs. above-ground termites
Tool use:
Bonobos
- Captive male “Kanzi” – taught to make and use stone tools
- Wild population uses leaves as sponges, throw sticks, use twigs to scratch, fend off bees
Tool use:
Orangutans
Only seen in a few groups- absent in most populations
- Use sticks to scratch, fend off bees, modify sticks to extract fruit, honey, insects
- Transmission of behaviour to other group members
Tool use:
Gorillas
- Use stick to test water depth, shrub trunk as a bridge
Tool use:
Monkeys
- Capuchins use stones to dig for grubs, tubers, crack open cashew nuts, and use sticks to get insects, honey
- Monkeys have used stone tools for hundreds of years
Zoopharmacognosy (Primate Medicine)
Consumption or anointment with plants, insects, soils, not for nutritional purposes
Examples:
• Capuchin monkeys rub themselves with citrus fruit containing antibacterial compounds
• Wedge-capped capuchins rub themselves with millipedes containing an insect repellent compound
• Geophagy (intentional consumption of soil) observed in many primates: Can neutralize plant toxins, treat GI upsets, protect against malaria
