Download Chapter 6 Primate Behavior

Chapter 7
Primate Behavior
Chapter Outline
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The Evolution of Behavior
Why Be Social?
Primate Social Behavior
Reproduction and Reproductive Behaviors
Mothers, Fathers, and Infants
Primate Cultural Behavior
Language
The Primate Continuum
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.
Behavioral Ecology
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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.
The Evolution of Behavior
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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.
Primate Social Structure
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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.
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.
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.
Factors That Influence Social
Structure
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Distribution of Resources
 Leaves can be abundant will support large
groups of animals.
 Fruits and nuts occur in clumps. These can
most efficiently be 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.
Factors That Influence Social
Structure
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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.
Factors That Influence Social
Structure
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Relationships with Other,
Nonpredatory Species
 Many primate species associate with
other primate and nonprimate species
for various reasons, including predator
avoidance.
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.
Factors That Influence Social
Structure
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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.
Factors That Influence Social
Structure
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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.
Factors That Influence Social
Structure
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Activity Patterns
 Nocturnal species tend to forage for food alone or in
groups of two or three and many use concealment to
avoid predators.
Factors That Influence 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.
Primate Social Behavior:
Dominance
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Many primate societies are organized into
dominance hierarchies.
These impose a certain degree of order by
establishing 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.”
Factors that Influence
Dominance Status
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Sex
Age
Aggression
Time in the group
Intelligence
Motivation
Mother’s social position
Primate Social Behavior:
Communication
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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.
Primate Social Behavior:
Aggression
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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.
Primate Social Behavior:
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.
Primate Social Behavior
Affiliative Behaviors
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Common affiliative behaviors include
reconciliation, consolation, and simple amicable
interactions between friends and relatives.
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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.
Patterns of Reproduction
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In most primate societies, sexual behavior
is tied to the female’s 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.
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)
Male competition for mates and mate
choice in females are both examples of
sexual selection.
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.
Infanticide As 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.
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.
Monkeys raised without a mother were not able
to form lasting affectional ties.
The mother-infant relationship is often
maintained throughout life.
Primate Cultural Behavior
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Cultural behavior is learned; it’s 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.
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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These views have been challenged:
 Vervet monkeys use specific vocalizations to
refer to particular categories of predators,
such as snakes, birds of prey, and leopards.
 Other studies have demonstrated that
numerous nonhuman primates produce
distinct calls that have specific references.
The Primate Continuum
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Human brains are larger than primate brains,
but the neurological processes are functionally
the same.
That humans are part of an evolutionary
continuum is the basis for animal research, yet
we cage nonhuman primates without regard for
their needs.
Nonhuman primates should be maintained in
social groups and introduced to habitat
enrichment programs.
Quick Quiz
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.
Answer: b
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Dominance hierarchies result in
dominant individuals having priority
access to food.
2. Affiliative behaviors
a) arise when there is competition for
resources.
b) enhance group cohesiveness.
c) are rare among primates.
d) may include displays.
Answer: b
• Affiliative behaviors enhance group
cohesiveness.
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.
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.