Transcript Jurmain Ess 9e PPT ch 7

CHAPTER 7
Primate Behavior
Chapter Outline
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The Evolution of Behavior
Why Be Social?
Primate Social Behavior
Reproduction and Reproductive Behaviors
Chapter Outline
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Mothers, Fathers, and Infants
Primate Cultural Behavior
Language
The Primate Continuum
Focus Question
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How can natural selection act on behavior, resulting
in similarities between human and nonhuman
primate behavior, including culture?
What is Meant By Behavior?
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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.
The Evolution of Behavior
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The underlying principles of behavioral evolution lie
in the interactions between a number of
environmental and physiological variables.
Ecological Perspective
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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.).
Behavioral Ecology
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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.
Thinking about Humans
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How is human ecology similar to and different from
that of non-human primates?
The Evolution of Behavior
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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
Social Structure
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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.
Primate Social Structure
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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
Some Factors That Influence Social Structure
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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.
Metabolism
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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.
Some Factors That Influence Social Structure
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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.
Some Factors That Influence Social
Structure
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Larger primates consume large amounts of lower quality
foods
Factors in Social Structure
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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.
Some Factors That Influence Social
Structure
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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.
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)
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Thinking About Humans
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How does the distribution of food resources among
humans and the diet of humans impact social group
size and composition?
Some Factors That Influence Social
Structure
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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.
Predation
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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.
Some Factors That Influence Social
Structure
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Relationships with Nonpredatory Species
 Many
primate species associate with other primate and
nonprimate species for various reasons, including
predator avoidance.
Some Factors That Influence Social
Structure
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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.
Thinking About Humans
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What patterns characterize human “dispersals”?
Some Factors That Influence Social
Structure
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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.
Some Factors That Influence Social
Structure
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Activity patterns
 Most primates are diurnal, but several smallbodied 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
Factors In Social Structure
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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.
Why Be Social?
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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.
Primate Social Behavior: Dominance
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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
Factors that Influence Dominance
Status
 Sex
 Age
 Aggression
 Time
in the group
 Intelligence
 Motivation
 Mother’s social position
Thinking About Humans
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How is social stratification similar to and different
from the dominance hierarchies found in many
primate species?
Primate Social Behavior:
Communication
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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.
Communication
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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.
Primate Communication
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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.”
Chimpanzee Facial Expressions
Primate Social Behavior:
Aggressive Interactions
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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.
Serious and Fatal Consequences of
Aggression
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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
Intergroup Aggression
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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.
Territories
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Members of a chimpanzee “border patrol” at Gombe survey
their territory from a tree.
Thinking About Humans
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How are primate aggressive behaviors similar to
and different from the violent actions that are
present in human societies?
Primate Social Behavior: Affiliation
and Altruism
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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.
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Grooming
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Picking through fur to remove dirt, parasites, and
other materials that may be present.
Social grooming is common among primates and
reinforces social relationships.
Reproduction and Reproductive
Behaviors
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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.
Reproductive Strategies
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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.
Thinking About Humans
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How are human marriage practices similar to and
different from primate reproductive strategies?
Sexual Selection
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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.
Sexual dimorphism in mandrills
Infanticide: A Reproductive
Strategy?
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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.
Hanuman langurs
Testing Hypotheses: Does Infanticide
Provide Selective Advantage?
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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?
Mothers, Fathers and Infants
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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.
Primate Bonding
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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.
Primate Bonding
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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.
Primate Cultural Behavior
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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.
Examples of Cultural Behavior
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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
Anthropocentric
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Viewing nonhuman animals in terms of human
motives, and experience and capabilities;
emphasizing the importance of humans over
everything else.
Language
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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.
Language
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Vervet monkeys use specific vocalizations to refer to
particular categories of predators, such as snakes,
birds of prey, and leopards.
Kanzi
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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.
Thinking About Humans
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How is primate communication similar to and
different from full human language?
Evolution of Human Language
The Biological Continuum
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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
Why It Matters
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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.
Why It Matters
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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.
QUICK QUIZ
1. Dominance hierarchies
a)
b)
c)
d)
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.
Answer: b
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Dominance hierarchies result in dominant
individuals having priority access to food.
2. Affiliative behaviors
a)
b)
c)
d)
arise when there is competition for resources.
enhance group cohesiveness.
are rare among primates.
may include displays.
Answer: b
• Affiliative behaviors enhance group cohesiveness.
3. Vervet monkey communication
a)
b)
c)
d)
is used to support the theory that primate
vocalizations do not include external events or
objects.
is limited to scent marking and an occasional bark.
includes specific sounds for different categories of
predators (air, tree or ground).
is sophisticated with regard to food.
Answer: c
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Vervet monkey communication includes specific
sounds for different categories of predators
(air, tree or ground).
4. In a group's territory there is usually a
_________________ area where the highest
concentration of resources can be found.
Answer: core
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In a group's territory there is usually a core area
where the highest concentration of resources can be
found.