Why Study Non-Human Primates?

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Why Study Non-Human Primates?
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Why Study Non-Human Primates?

• 1. Behaviors universal among modern primates
  give us clues to our ancestors behavior
• 2. Allows reconstruction of social structure,
  ecology, and intelligence of early humans
• 3. Compare and contrast primate social
  organizations, communication, intelligence
• 4. Better understand the environmental factors
  that led to the divergence of the human lineage
• 5. Learn how we can preserve the endangered
  primates

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The Evolution of Behavior

• Behavior has evolved through natural selection
• Individuals act to maximize their own
  reproductive success
• Natural selection acts on behaviors in the same
  way it acts on physical characteristics
• Behavior is the product of complex interactions
  between genetic and environmental factors

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Factors That Influence Behavior

• Quantity and quality of foods
• Spatial distribution of food resources
• Distribution and reliability of water supplies
• Body size
• Distribution and types of predators

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More Factors That Influence Behavior

• Distribution and types of sleeping sites
• Activity patterns
• Relationships with other nonpredator species
• Impact of human activities

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Comparing Behavior

• HOMOLOGIES Traits shared by 2 or more species
  through inheritance from a common ancestor
• Ex. chimps more homologous to humans (diverged
  5 mya) v. baboons humans (diverged 20 mya)
• ANALOGIES Traits shared by 2 or more species
  that are similar in function but not
  evolutionarily related
• Ex. bat and insect wings
• The more evolutionarily distant, the less useful
  the comparison!

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Dominance

• Relative hierarchical position of an individual
  in a social group
• Most primate societies are organized into
  dominance hierarchies
• Reduces the amount of actual physical violence
  determines who gets what when
• Dominant animals can often exert control with
  only a gesture

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Dominance (cont.)

• Measured by looking at access to limited
  resources, interactions between individuals
• Influenced by age, sex, personality, amount of
  time in the group, intelligence, mothers status,
  number of relatives in the group
• Status is learned

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Communication

• Transmission of information through the senses
• Scents, facial expressions, gestures, postures,
  vocalizations
• Displays repetitious behaviors that communicate
  emotional states
• May be unintentional or intentional
• Submissive gestures reduce aggression
• Functions threaten, invite play or grooming,
  express dominance, reassure, greet, warn about
  predators, etc.

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Aggression

• Conflict develops out of competition for
  resources
• Most situations are resolved through submissive
  and appeasement behaviors
• Competition for mates frequently results in
  injury, and occasionally death

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Affiliative Behaviors

• Physical contact promotes peace in social groups
• Grooming reinforces social bonds
• Relationships are crucial and bonds between
  individuals can last a lifetime
• Altruism is common among many primate species

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Affiliative Behaviors (cont.)

• Reconciliation, consolation, and friendly
  interactions
• Based on physical contact (hugging, hand holding,
  touching, kissing)
• Nonhuman primates form alliances two or more
  animals join together for a common purpose

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Play

• Difficult to define, but you know it when you see
  it
• Occurs most commonly in infants and juveniles
• Requires curiosity (intelligence?) and can be
  dangerousrequires parental vigilance
• Functions to build the individuals mental,
  social, and physical skills
• Time spent in play declines when the individual
  is stressed (e.g. malnutrition)
• Adults also play, but usually is oriented toward
  parenting responsibilities

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Patterns of Reproduction

• Females are receptive to males only when they are
  in estrus
• Permanent bonding is not common
• Sometimes, mating relationships are formed,
  temporary relationships that last while the
  female is in estrus

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Reproductive Strategies

• Estrus behavioral and physical changes that
  indicate that a female is ovulating and receptive
  to copulation
• Some primates (including humans, gibbons, and
  bonobos) mate throughout the females cycle and
  give no obvious signals of ovulation
• Influences how the two sexes interact and the
  species mating system

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Reproductive Strategies (cont.)

• Females spend almost all of their adult lives
  pregnant, lactating and/or caring for offspring
• Males try to secure as many mates as possible to
  increase genetic contribution to the next
  generation

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Mothers and Infants

• Basic social unit among primates
• Monkeys and apes raised in captivity without
  contact with their own mothers did not know how
  to care for infants
• Males do not participate greatly in the rearing
  of offspring

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Culture

• Culture is learned and passed on from one
  generation to the next
• May be learned through instruction (common only
  for humans) and through observation (common in
  all primates)
• Cultural traditions are behaviors that become
  common in the entire group
• Examples washing potatoes, tool use, dietary
  preferences, greeting styles

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Primate Behavior Some Key Terms

• AnthropocentricViewing nonhuman primates in
  terms of human experience emphasizing the
  importance of humans over everything else
• Dominance hierarchiesIndividuals within a group
  are ranked relative to one another
• GroomingPicking through fur to remove dirt,
  parasites, and other materials, reinforces social
  relationships

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Primate Behavior Some Key Terms

• Reproductive strategiesBehavior patterns that
  contribute to individual reproductive success
• Sexual selectionType of natural selection that
  operates on only one sex within a species
• AltruismAny behavior or act that benefits
  another individual but poses some potential risk
  or cost to oneself (adoption, protecting young,
  helping another in a fight)

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Langur Old World Monkey (Vietnam, India,
Cambodia)
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Langur Takeover Behavior

• Social Organization 1 adult male, several adult
  females, offspring other males live in
  bachelor groups
• Takeovers involve running out the resident male
  and killing all unweaned infants

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Why do Langurs Takeover?

• Males kill infants to cause mothers to begin
  reproductive cycles
• Takeover male can father offspring faster than if
  he waited 1-2 years for weaning to occur
• Male tenure in the group is short--3 years or
  less
• Takeover male is attempting to maximize his
  reproductive success

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Dettwyler questions

• Describe the goals and methods of the CARE health
  projects in the villages around Macina in
  northern Mali. What kinds of problems did the
  villagers face, and how did the CARE project help
  them deal wih their problems?
• Why does Katherine Dettwyler say that good
  nutrition may be more important than immunization
  against specific diseases or oral rehydration
  therapy, in the long run?
• How should development projects be designed?
  That is, who should decide what needs to be done
  and how to go about doing it? How much input
  should the villagers themselves have in designing
  and implementing projects? Give an example.