Primate Behavior

1
Chapter 7

• Primate Behavior

2
Chapter Outline

• Primate Field Studies
• The Evolution of Behavior
• Sympatric Species
• Why Be Social?
• Primate Social Behavior

3
Chapter Outline

• Reproduction and Reproductive Behaviors
• Mothers, Fathers, and Infants
• Issue Primates in Biomedical Research Ethics
  and Concerns

4
Behavior

• Anything organisms do that involves action in
  response to internal or external stimuli.
• The response of an individual, group, or species
  to its environment.
• Such responses may or may not be deliberate and
  they arent necessarily the results of conscious
  decision making.

5
Free-ranging

• Pertaining to non-captive animals living in their
  natural habitat.
• Ideally, the behavior of wild study groups would
  be free of human influence.

6
Social Structure

• The composition, size, and sex ratio of a group
  of animals.
• Social structures are the results of natural
  selection in specific habitats, and they
  influence individual interactions and social
  relationships.
• In many species, social structure varies,
  depending on different environmental factors.
• Thus, in most primate species, social structure
  should be viewed as flexible, not fixed.

7
Observing Primates

• (a) Rhesus macaques spend much of their time on
  the ground and are easier to observe than (b)
  black-and-white colobus.

8
Behavioral Ecology

• An approach that focuses on the relationship
  between behaviors, the natural environment, and
  biological traits of the species.
• Based on the assumption that animals, plants, and
  microorganisms evolved together.
• Some behaviors are influenced by genes and are
  subject to natural selection the same way
  physical characteristics are.

9
The Evolution of Behavior

• Individuals with behavioral phenotypes that
  increase reproductive fitness pass on their genes
  at a faster rate than others.
• Behavior is a product of interactions between
  genetic and environmental factors.
• Species vary in their limits and potentials for
  learning and for behavioral flexibility.
• These limits and potentials are set by genetic
  factors favored throughout the evolutionary
  history of every species.

10
Primate Social Structure

• Social structures are the results of natural
  selection in specific habitats.
• They guide individual interactions and social
  relationships.
• Primates are among the most social of animals, so
  social behavior is one of the major topics in
  primate research.

11
Factors That Influence Social Structure Body Size

• Larger animals are better able to retain heat and
  their overall energy requirements are less than
  for smaller animals.

12
Factors That Influence Social Structure

• Basal Metabolic Rate (BMR) and Diet
• Smaller animals generally have a higher BMR than
  larger ones.
• Consequently, smaller primates require an
  energy-rich diet high in protein, fats, and
  carbohydrates.

13
Metabolism

• The chemical processes within cells that break
  down nutrients and release energy for the body to
  use.

14
Factors That Influence Social Structure

• Distribution of Resources
• Leaves can be abundant and will support large
  groups of animals.
• Fruits and nuts occur in clumps. These can be
  efficiently exploited by smaller groups of
  animals.
• Some species that rely on foods distributed in
  small clumps tend to be protective of resources,
  especially if their feeding area is small enough
  to be defended.

15
Distribution of Resources

• This male mountain gorilla has only to reach out
  to find something to eat.

16
Factors That Influence Social Structure

• Predation
• Primates are vulnerable to many types of
  predators, including snakes,birds of prey,
  leopards, wild dogs, lions, and even other
  primates.
• Where predation pressure is high, large
  communities are advantageous.
• These may be multimale-multifemale groups or
  congregations of one-male groups.

17
Factors That Influence Social Structure

• Relationships with Other, Nonpredatory Species
• Many primate species associate with other primate
  and nonprimate species for various reasons,
  including predator avoidance.

18
Factors That Influence Social Structure

• Dispersal
• Members of one sex leave the group in which they
  were born when they become sexually mature.
• Individuals who leave find mates outside their
  natal group, so dispersal is believed to decrease
  the likelihood of close inbreeding.

19
Factors That Influence Social Structure

• Life Histories
• Life history traits are characteristics or
  developmental stages that typify members of a
  species and influence reproductive rates.
• Examples length of gestation, length of time
  between pregnancies, period of infant dependency
  and age at weaning, age of sexual maturity, and
  life expectancy.

20
Factors That Influence Social Structure

• Distribution and Types of Sleeping Sites
• Gorillas are the only nonhuman primates that
  sleep on the ground.
• Primate sleeping sites can be in trees or on
  cliff faces, and their spacing can be related to
  social structure, predator avoidance, and how
  many sleeping sites are available.

21
Factors That Influence Social Structure

• Activity Patterns
• Nocturnal species tend to forage for food alone
  or in groups of two or three and many use
  concealment to avoid predators.

22
Factors That Influence Social Structure

• Human Activities
• Virtually all nonhuman primate populations are
  impacted by human hunting and forest clearing.
• These activities disrupt and isolate groups,
  reduce numbers, reduce resource availability, and
  eventually can cause extinction.

23
Matrilines

• Groupings of females who are all descendants of
  one female (e.g., a female, her daughters,
  granddaughters, and their offspring).
• Matrilines also include dependent male offspring.
  
• Among macaques, some matrilines are dominant to
  others, so that members of dominant matrilines
  have greater access to resources than do members
  of subordinate ones.

24
Types of Nonhuman Primate Social Groups

• One male-multifemale.
• Am adult male, several adult females, and
  offspring.
• The most common structure, typically formed by a
  male joining a kin group of females.
• Females usually form the permanent group.
• Examples guenons, gorillas, some pottos, some
  spider monkeys, patas, some langurs, and some
  colobus.

25
Types of Nonhuman Primate Social Groups

• Multimale-multifemale
• Several adult males, several adult females, and
  their young.
• The presence of several males may lead to a
  dominance hierarchy.
• Examples some lemurs, macaques, mangabeys,
  savanna baboons, vervets, squirrel monkeys, some
  spider monkeys, and chimpanzees.

26
Types of Nonhuman Primate Social Groups

• Monogamous pair
• The least common breeding structure among
  nonhuman primates.
• Extra-pair matings arent uncommon.
• Species that form pairs are usually arboreal,
  show minimal sexual dimorphism, and are
  frequently territorial.
• Examples siamangs, gibbons, indris, titis,
  sakis, owl monkeys, and pottos.

27
Types of Nonhuman Primate Social Groups

• Polyandry
• One female and two males.
• This social group is seen only in some New World
  monkeys (marmosets and tamarins).
• Males participate in care of infants.

28
Types of Nonhuman Primate Social Groups

• Solitary
• Individual forages for food alone.
• This group is seen in some nocturnal prosimians
  (aye-ayes, lorises, and galagos).
• In some species, adult females may forage in
  pairs or may be accompanied by offspring.
• Also seen in orangutans.

29
Philopatric

• Remaining in ones natal group or home range as
  an adult.
• In most species, members of one sex disperse from
  their natal group as young adults, and members of
  the philopatric sex remain.
• In most of the nonhuman primate species, the
  philopatric sex is female.

30
Life History Traits

• Characteristics and developmental stages that
  influence rates of reproduction.
• Examples include longevity age at sexual
  maturity length of time between births, etc.

31
Strategies

• Behaviors or behavioral complexes that have been
  favored by natural selection to increase
  individual reproductive fitness.

32
Sympatric

• Living in the same area.
• Pertaining to two or more species whose habitats
  partly or largely overlap.

33
Primate Social Strategies
34
Home Range

• The total area exploited by an animal or social
  group.
• Usually given for 1 yearor for the entire
  lifetimeof an animal.

35
Predators

• When a baboon strays too far from its troop, its
  more likely to fall prey to predators.
• Leopards are the most serious nonhuman threat to
  terrestrial primates.

36
Primate Social Behavior Dominance

• Many primate societies are organized into
  dominance hierarchies.
• These impose order by establishing parameters of
  individual behavior.
• Higher-ranking animals have greater access to
  preferred food and mating partners than lower
  ranking individuals.
• Dominance hierarchies are sometimes called
  pecking orders.

37
Breeding and Suppressed Males

• Fully mature, breeding male orangutan with
  well-developed cheek pads (a) compared to a
  suppressed adult male without cheek pads (b).

38
Factors that Influence Dominance Status

• Sex
• Age
• Aggression
• Time in the group
• Intelligence
• Motivation
• Mothers social position

39
Dominance

• One young male savanna baboon mounts another as
  an expression of dominance.

40
Primate Social Behavior Communication

• Raised body hair is an example of an autonomic
  response.
• Vocalizations and branch shaking are examples of
  deliberate communication.
• Reassurance is communicated through hugging or
  holding hands.
• The fear grin, seen in all primates, indicates
  fear and submission.
• Displays communicate emotional states.

41
Threatening Behavior

• An adolescent male savanna baboon threatens with
  a characteristic yawn that shows the canine
  teeth.
• Note that the eyes are closed briefly to expose
  light, cream colored eyelids.
• This has been termed the eyelid flash.

42
Question

• Dominance hierarchies
• guarantee that dominant males are more
  reproductively successful.
• result in dominant individuals having priority
  access to food.
• don't guarantee a reproductive advantage in
  dominant males.
• are permanent.

43
Answer b

• Dominance hierarchies result in dominant
  individuals having priority access to food.

44
Primate Social Behavior Aggression

• Conflict within a group frequently develops out
  of competition for resources, including mating
  partners and food items.
• Most intragroup aggression occurs in the form of
  various signals and displays within the context
  of a dominance hierarchy.
• Most tense situations are resolved through
  various submissive and appeasement behaviors.

45
Primate Social Behavior Aggression

• Primate groups are associated with a home range
  where they remain permanently.
• Within the home range is a portion called the
  core area, which contains the highest
  concentration of predictable resources, and its
  where the group is most frequently found.
• The core area can also be said to be a groups
  territory, and its the portion of the home range
  defended against intrusion.

46
Displays

• Sequences of repetitious behaviors that serve to
  communicate emotional states.
• Nonhuman primate displays are most frequently
  associated with reproductive or agonistic
  behavior.

47
Chimpanzee Facial Expressions
48
Ritualized Behaviors

• Behaviors removed from their original context and
  sometimes exaggerated to convey information.

49
Primate Social Behavior Affiliative Behaviors

• Common affiliative behaviors include
  reconciliation, consolation, and simple amicable
  interactions between friends and relatives.
• Hugging, kissing and grooming are all forms used
  in reconciliation.
• Relationships are crucial to nonhuman primates
  and the bonds between individuals can last a
  lifetime.
• Altruism, behaviors that benefit another while
  posing risk to oneself, are common in primate
  species.

50
Grooming Primates

• (a) Patas monkeys female grooming male. (b)
  Longtail macaques. (c) Savanna baboons. (d)
  Chimpanzees

51
Grooming

• Picking through fur to remove dirt, parasites,
  and other materials that may be present.
• Social grooming is common among primates and
  reinforces social relationships.

52
Question

• Affiliative behaviors
• arise when there is competition for resources.
• enhance group cohesiveness.
• are rare among primates.
• may include displays.

53
Answer b

• Affiliative behaviors enhance group cohesiveness.

54
Patterns of Reproduction

• In most primate societies, sexual behavior is
  tied to the females reproductive cycle.
• Permanent bonding is not common among nonhuman
  primates.
• Male and female Bonobos may mate even when the
  female is not in estrus, a behavior that is not
  typical of chimpanzees.

55
Estrous Swelling in a Female Chimpanzee
56
Reproductive Strategies

• Behavioral patterns that contribute to individual
  reproductive success.
• Primates produce only a few young in whom they
  invest a tremendous amount of parental care. (k
  selected)
• Male competition for mates and mate choice in
  females are both examples of sexual selection.

57
K-selected

• An adaptive strategy whereby individuals produce
  relatively few offspring, in whom they invest
  increased parental care.
• R-selected - An adaptive strategy that emphasizes
  large numbers of offspring and reduced parental
  care.
• K-selection and r-selection are relative (e.g.,
  mice are r-selected compared to primates but
  K-selected compared to many fish species).

58
Sexual Selection

• A type of natural selection that operates on one
  sex, usually males.
• Long-term, this increases the frequency of traits
  that lead to greater success in acquiring mates.
• Sexual selection in primates is most common in
  species in which mating is polygynous and male
  competition for females is prominent.
• Sexual selection produces dimorphism with regard
  to a number of traits, most noticeably body size.

59
Infanticide As A Reproductive Strategy?

• One way males increase their chances of
  reproducing is by killing infants fathered by
  other males.
• Individuals maximize their reproductive success,
  no matter the effect on population or species.
• When an infant dies, its mother resumes cycling
  and becomes sexually receptive.
• An infanticidal male avoids waiting two to three
  years for the infants to be weaned before he can
  mate with their mothers.

60
Mothers, Fathers and Infants

• The basic social unit among primates is the
  female and her infants.
• Except in species in which monogamy or polyandry
  occur, males do help rear offspring.
• Monkeys raised without a mother were not able to
  form lasting affectional ties.
• The mother-infant relationship is often
  maintained throughout life.

61
Primate mothers with young.

• (a) Sykes monkey. (b) Patas monkey.

62
Primate mothers with young.

• (c) Mongoose lemur. (d) Orangutan. (e) Chimpanzee.

63
Infant Macaque Clinging to Cloth Mother
64
Primate Cultural Behavior

• Cultural behavior is passed from generation to
  generation through learning.
• Nonhuman primate infants, through observing their
  mothers and others, learn about food items,
  appropriate behaviors, and how to use and modify
  objects to achieve certain ends.
• Chimpanzee culture includes tools such as termite
  fishing sticks and leaf sponges.