1. CHAPTER 7 Primate Behavior

2. Chapter Outline  The Evolution of Behavior  Why Be Social?  Primate Social Behavior  Reproduction and Reproductive Behaviors

3. Chapter Outline  Mothers, Fathers, and Infants  Primate Cultural Behavior  Language  The Primate Continuum

4. Focus Question  How can natural selection act on behavior, resulting in similarities between human and nonhuman primate behavior, including culture?

5. What is Meant By 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 aren’t necessarily the results of conscious decision making.

6. The Evolution of Behavior  The underlying principles of behavioral evolution lie in the interactions between a number of environmental and physiological variables.

7. Ecological Perspective  Pertains to relationships between organisms and all aspects of their environment (temperature, predators, vegetation, availability of food and water, types of food, disease organisms, parasites, etc.).

8. Behavioral Ecology  Focuses on the relationship between behaviors, natural environment, and biological traits of the species.  Based on the assumption that animals, plants, and microorganisms evolved together.  Behaviors have evolved through the operation of natural selection, or  Some behaviors are influenced by genes and are subject to natural selection the same way physical characteristics are.

9. Thinking about Humans  How is human ecology similar to and different from that of non-human primates?

10. The Evolution of Behavior  Behavior constitutes a phenotype  Individuals whose behavioral phenotypes increase reproductive fitness pass on their genes at a faster rate.  Genes do not code for specific behaviors, however (i.e. aggression, cooperation, etc.)  Species vary in their limits and potentials for learning and behavioral flexibility, set by genetic factors.  Natural selection acts on genetic factors shaped by ecological setting of past and present

11. Social Structure  The composition, size, and sex ratio of a group of animals.  The social structure of a species is, in part, the result of natural selection in a specific habitat, and it guides individual interactions and social relationships.

12. Primate Social Structure  Primates are among the most social of animals, and social behavior is one of the major topics in primate research.  The subject is broad, including all aspects of behavior that occur in social settings

13. Some Factors That Influence Social Structure  Body Size  Larger animals require fewer calories per unit of weight than smaller animals.  Larger animals are better able to retain heat and their overall energy requirements are less than for smaller animals.

14. Metabolism  The chemical processes within cells that break down nutrients and release energy for the body to use.  When nutrients are broken down into their component parts, such as amino acids, energy is released and made available for the cell to use.

15. Some 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.

16. Some Factors That Influence Social Structure  Larger primates consume large amounts of lower quality foods

17. Factors in Social Structure  Diet  Nutritional needs have evolved along with BMR and body size  Benefits are considered in terms of energy (calories) obtained from food versus costs (energy expended) of obtaining and digesting them.

18. Some Factors That Influence Social Structure  Distribution of Resources  Leaves are abundant, dense, and support large groups of animals.  Insects are widely scattered, causing animals to feed on them alone or in small groups of two or three  Fruits and nuts occur in clumps and are most efficiently exploited by smaller groups of animals; large groups break up into smaller subunits to feed.

19. Primate Social Groupings  Species that rely on foods distributed in clumps tend to be protective of resources, especially if the feeding area is small enough to be defended.  These subunits may consist of one-male, multi-female groups (example: baboons) or matrilines (example: macaques) that consist of a female, her daughters, and their offspring  One-male units, able to join with others because food is plentiful, form large, stable communities (examples: howlers and baboons)

21. Thinking About Humans  How does the distribution of food resources among humans and the diet of humans impact social group size and composition?

22. Some Factors That Influence Social Structure  Predation  Primates are vulnerable to many 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 multi-male, multi-female groups or congregations of one-male groups.

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

24. Some Factors That Influence Social Structure  Relationships with Nonpredatory Species  Many primate species associate with other primate and nonprimate species for various reasons, including predator avoidance.

25. Some 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.

26. Thinking About Humans  What patterns characterize human “dispersals”?

27. Some Factors That Influence Social Structure  Life Histories  Characteristics or developmental stages that typify members of a species and influence reproductive rates.  Examples: length of gestation, time between pregnancies, period of infant dependency and age at weaning, age of sexual maturity, and life expectancy.  Unpredictable environments favor shorter life histories and stable ones, longer lives  Today, the slow rate of reproduction increases the threat of extinction for all the great apes.

28. Some Factors That Influence Social Structure  Activity patterns  Most primates are diurnal, but several small- bodied promisians and the owl monkey are nocturnal  Nocturnal primates tend to forage for food alone or in groups of 2 or 3, and use concealment to avoid predators

29. Factors In 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.

30. Why Be Social?  Group living exposes animals to competition with other group members, so why not live alone?  Costs of competition are offset by the benefits of predator defense provided by associating with others.  Group living evolved as an adaptive response to a number of ecological variables.

31. Primate Social Behavior: Dominance  Many primate societies are organized into dominance hierarchies that impose order and establish parameters of individual behavior.  Higher-ranking animals have greater access to preferred food items and mating partners than lower ranking individuals.  Dominance hierarchies are sometimes called “pecking orders” that change throughout one’s life and are learned

32. Factors that Influence Dominance Status  Sex  Age  Aggression  Time in the group  Intelligence  Motivation  Mother’s social position

33. Thinking About Humans  How is social stratification similar to and different from the dominance hierarchies found in many primate species?

34. Primate Social Behavior: Communication  Any act that conveys information to another individual.  Frequently, the result of communication is a change in the behavior of the recipient.  Communication may be the result of involuntary processes or a secondary consequence of an intentional action.

35. Communication  Raised body hair is an example of an autonomic, or unintentional, response.  Gestures, facial expressions, and vocalizations are examples of deliberate communication.  The fear grin, seen in all primates, indicates fear and submission.  Grooming serves to indicate submission or reassurance.  Displays communicate emotional states.

36. Primate Communication  An adolescent male savanna baboon threatens the photographer with a “yawn” that shows the canine teeth.  The eyes are closed briefly to expose cream-colored eyelids.  This has been called the “eyelid flash.”

37. Chimpanzee Facial Expressions

38. Primate Social Behavior: Aggressive Interactions  Lead to group disruption, as opposed to affiliative behavior, which promote group cohesion.  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.

39. Serious and Fatal Consequences of Aggression  Dominant actions can keep subordinates away from food and using weight loss and poor nutrition, threatening reproductive success of subordinates  Competition can result in injury and death

40. Intergroup 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 it’s where the group is most frequently found.  The core area can also be said to be a group’s territory, and it’s the portion of the home range defended against intrusion.

41. Territories  Members of a chimpanzee “border patrol” at Gombe survey their territory from a tree.

42. Thinking About Humans  How are primate aggressive behaviors similar to and different from the violent actions that are present in human societies?

43. Primate Social Behavior: Affiliation and Altruism  Common affiliative behaviors include reconciliation, consolation, and interactions between friends and relatives.  Hugging, kissing and grooming are 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.

44. 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.

45. Reproduction and Reproductive Behaviors  In most primate societies, sexual behavior is tied to the female’s reproductive cycle--estrus.  Permanent bonding between females and males 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.

46. 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) (contrast r-selected)  Male competition for mates and mate choice in females are both examples of sexual selection.

47. Thinking About Humans  How are human marriage practices similar to and different from primate reproductive strategies?

48. 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.

49. Sexual dimorphism in mandrills

50. Infanticide: 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.

51. Hanuman langurs

52. Testing Hypotheses: Does Infanticide Provide Selective Advantage?  Infanticidal males don’t kill their own offspring.  Once a male has killed an infant, he subsequently fathers another infant with the victim’s mother.  What data would support the hypotheses?

53. Mothers, Fathers and Infants  The basic social unit among all primates is the female and her infants.  Except in species in which monogamy or polyandry occur, males do not participate in rearing offspring.  The mother-infant relationship is often maintained throughout life.

54. Primate Bonding  The role of bonding between primate mothers and infants was demonstrated in experiments at the University of Wisconsin.  Psychologist Harlow raised infant monkeys with surrogate mothers made of wire or a combination of wire and cloth.  Other monkeys were raised with no mother at all.

55. Primate Bonding  In am experiment, infants raised with no mother were incapable of forming lasting ties.  None of the motherless males successfully copulated, and females who were impregnated either paid little attention to or were aggressive toward infants.

57. Primate Cultural Behavior  Cultural behavior is learned; it is passed from generation to generation through observation and instruction.  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.  More complex, chimpanzee culture includes tools such as termite fishing sticks and leaf sponges.

59. Examples of Cultural Behavior  Japanese macaques and sweet potato washing  Orangutan nest building  Gorilla depth desting  Chimpanzee termite fishing, leaf sponges, hunting “spears,” nut cracking  Kanzi’s stone tool making

61. Anthropocentric  Viewing nonhuman animals in terms of human motives, and experience and capabilities; emphasizing the importance of humans over everything else.

62. Language  Nonhuman animals haven’t been considered capable of communicating about external events, objects, or other animals.  It has been assumed that nonhuman animals use a closed system of communication, where vocalizations don’t include references to specific external phenomena.

63. Language  Vervet monkeys use specific vocalizations to refer to particular categories of predators, such as snakes, birds of prey, and leopards.

64. Kanzi  Kanzi, a Bonobo, began using symbols when he was 21/2 years old and his younger half-sister began using symbols at 11 months old.  Both went to training sessions with their mother, but neither had been taught or were involved in the sessions.

65. Thinking About Humans  How is primate communication similar to and different from full human language?

66. Evolution of Human Language

67. The Biological Continuum  Human brains are larger than primate brains, but the neurological processes are functionally the same.  The necessity of close bonding with at least one parent  Need for physical contact  Developmental stages and dependence on learning  Capacity for cruelty, aggression, compassion, altruism, with humans more adept at cruelty and compassion and capability to reflect on behavior

68. Why It Matters  Can we learn anything useful for our own species by observing primates in their natural settings?  Evidence of self medication by chimpanzees suggests that we may be able to identify beneficial human drugs by observing chimpanzee behavior.

69. Why It Matters  Primatologist Richard Wrangham noted that chimpanzees occasionally seek out a leaf that isn’t normally part of the diet.  Analysis revealed the leaf has high levels of antibiotic properties, suggesting chimpanzees use it to control intestinal parasites.  Plants consumed by chimpanzees contain compounds that may be useful for controlling malaria, Staphylococcus infections, E. coli, and cancer.

70. QUICK QUIZ

71. 1. Dominance hierarchies a) guarantee that dominant males are more reproductively successful. b) result in dominant individuals having priority access to food. c) don't guarantee a reproductive advantage in dominant males. d) are permanent.

72. Answer: b  Dominance hierarchies result in dominant individuals having priority access to food.

73. 2. Affiliative behaviors a) arise when there is competition for resources. b) enhance group cohesiveness. c) are rare among primates. d) may include displays.

74. Answer: b Affiliative behaviors enhance group cohesiveness.

75. 3. Vervet monkey communication a) is used to support the theory that primate vocalizations do not include external events or objects. b) is limited to scent marking and an occasional bark. c) includes specific sounds for different categories of predators (air, tree or ground). d) is sophisticated with regard to food.

76. Answer: c  Vervet monkey communication includes specific sounds for different categories of predators (air, tree or ground).

77. 4. In a group's territory there is usually a _________________ area where the highest concentration of resources can be found.

78. Answer: core  In a group's territory there is usually a core area where the highest concentration of resources can be found.