Social InteractionsSocial Interactions

Chapter 46Chapter 46

Animal BehaviorAnimal Behavior

Observable coordinated responses to Observable coordinated responses to

stimulistimuli

Originates with genes that direct the Originates with genes that direct the

formation of tissues and organs of the formation of tissues and organs of the

animal bodyanimal body

Nervous SystemNervous System

Detects processes and integrates Detects processes and integrates

information about stimuliinformation about stimuli

Commands muscles and glands to Commands muscles and glands to

make suitable responsesmake suitable responses

Starling Nest DecorationStarling Nest Decoration

Starlings line nest Starlings line nest

with wild carrotwith wild carrot

Experiments have Experiments have

shown this shown this

behavior behavior

minimizes mitesminimizes mites

Experimental nests

Control nestsFigure 46.2 Page 826

Genes and Behavior Genes and Behavior

Some variations in behavior have a Some variations in behavior have a

genetic basisgenetic basis

Arnold showed that garter snakes’ taste Arnold showed that garter snakes’ taste

for slugs has genetic basisfor slugs has genetic basis

Hybrid snakes showed behavior Hybrid snakes showed behavior

intermediate between parental types intermediate between parental types

Hormones and Bird SongHormones and Bird Song

Sex hormones produced during Sex hormones produced during

development prime male birds to sing development prime male birds to sing

As adults, males will sing only when As adults, males will sing only when

days are long and levels of the days are long and levels of the

hormone melatonin are lowhormone melatonin are low

Instinctive BehaviorInstinctive Behavior

Performed without having been learnedPerformed without having been learned

Usually triggered by simple sign stimuliUsually triggered by simple sign stimuli

Response is a stereotyped motor Response is a stereotyped motor

program, a fixed-action patternprogram, a fixed-action pattern

Learned Behavior Learned Behavior

Responses change with experienceResponses change with experience

Some categories of learned behaviorSome categories of learned behavior

ImprintingImprinting Spatial learning Insight Spatial learning Insight

learninglearning Habituation Habituation

Classical conditioningClassical conditioning

Operant conditioningOperant conditioning

ImprintingImprinting

Time-dependent learningTime-dependent learning

Triggered by exposure to a sign Triggered by exposure to a sign

stimulus during a sensitive periodstimulus during a sensitive period

Young geese imprint on a moving Young geese imprint on a moving

object and treat it as “mother”object and treat it as “mother”

Classical ConditioningClassical Conditioning

First demonstrated by PavlovFirst demonstrated by Pavlov

An autonomic response becomes An autonomic response becomes

associated with a novel stimulusassociated with a novel stimulus

Salivation became associated with Salivation became associated with

sound of bell that accompanied feedingsound of bell that accompanied feeding

Operant ConditioningOperant Conditioning

A voluntary action becomes associated A voluntary action becomes associated

with its consequenceswith its consequences

A toad may attempt to eat a wasp with a A toad may attempt to eat a wasp with a

black and gold pattern and be stungblack and gold pattern and be stung

Thereafter, the toad will be conditioned Thereafter, the toad will be conditioned

to avoid eating similar insectsto avoid eating similar insects

HabituationHabituation

An individual learns not to respond to An individual learns not to respond to

a stimulus that has neither good nor a stimulus that has neither good nor

bad consequencesbad consequences

Pigeons in cities learn that people Pigeons in cities learn that people

are no threat and do not flee from are no threat and do not flee from

themthem

Spatial LearningSpatial Learning

Through experience with an Through experience with an

environment, an organism creates a environment, an organism creates a

mental mapmental map

Some blue jays remember the Some blue jays remember the

location of dozens of places where location of dozens of places where

they have stored foodthey have stored food

Insight LearningInsight Learning

An animal solves a problem without An animal solves a problem without

trial-and-error attempts at a solutiontrial-and-error attempts at a solution

Captive chimpanzees show insight Captive chimpanzees show insight

learning when they solve a novel learning when they solve a novel

problem, as when they stack boxes problem, as when they stack boxes

to reach food that is out of reachto reach food that is out of reach

Bird Song: Instinct + LearningBird Song: Instinct + Learning

Bird comes prewired to listen to Bird comes prewired to listen to

certain acoustical cues; instinctively certain acoustical cues; instinctively

pays attention to particular soundspays attention to particular sounds

Which dialect the bird sings depends Which dialect the bird sings depends

on what song it hears; it learns the on what song it hears; it learns the

details of the song from others details of the song from others

around it around it

Selection for Behavior Selection for Behavior

Some variation in behavior has a genetic Some variation in behavior has a genetic

basisbasis

Some behavior promotes reproductive Some behavior promotes reproductive

success (is adaptive)success (is adaptive)

Genes that encode adaptive behavior Genes that encode adaptive behavior

will increase in populationwill increase in population

Adaptive BehaviorAdaptive Behavior

Behavior that promotes propagation Behavior that promotes propagation

of an individual’s genesof an individual’s genes

Its frequency will be maintained or Its frequency will be maintained or

increase in successive generationsincrease in successive generations

Selfish and Altruistic BehaviorSelfish and Altruistic Behavior

Selfish behavior promotes an Selfish behavior promotes an

individual’s genes at the expense of individual’s genes at the expense of

othersothers

Altruistic behavior helps others at the Altruistic behavior helps others at the

expense of the altruist; may be expense of the altruist; may be

adaptive under certain adaptive under certain

circumstancescircumstances

Selfish RavensSelfish Ravens

Some ravens that find carcasses call Some ravens that find carcasses call

and alert othersand alert others

Are their calls altruistic? NoAre their calls altruistic? No

Callers are birds without territoriesCallers are birds without territories

Calling brings in others to help caller Calling brings in others to help caller

get food in a pair’s territoryget food in a pair’s territory

Communication Signals Communication Signals

Intraspecific signals will evolve only if Intraspecific signals will evolve only if

they benefit both signaler and receiverthey benefit both signaler and receiver

Variety of signal modalitiesVariety of signal modalities

PheromonesPheromones Tactile signalsTactile signals

Visual signalsVisual signals

Acoustical signalsAcoustical signals

PheromonesPheromones

Chemical signals that diffuse through Chemical signals that diffuse through

air or waterair or water

May bring about behavioral change May bring about behavioral change

in receiver or cause physiological in receiver or cause physiological

change (priming pheromones)change (priming pheromones)

Acoustical SignalsAcoustical Signals

Sounds used in communicationSounds used in communication

Used to attract mates, secure Used to attract mates, secure

territory, warn off rivals territory, warn off rivals

May also be used to communicate May also be used to communicate

danger, keep groups togetherdanger, keep groups together

Visual DisplaysVisual Displays

Important in courtship and in Important in courtship and in

aggressionaggression

Baring of teeth by baboon Baring of teeth by baboon

communicates threatcommunicates threat

Play bow in wolves solicits play Play bow in wolves solicits play

behaviorbehavior

Flashing of fireflies attracts matesFlashing of fireflies attracts mates

Tactile DisplayTactile Display

Signaler and receiver communicate Signaler and receiver communicate by touchby touch

Honeybee dance language Honeybee dance language

Figure 46.10 Page 833

Food close Food distant

Signal VariationSignal Variation

Some signals never varySome signals never vary

Others can be varied to convey Others can be varied to convey

information about the signalerinformation about the signaler

Composite signals combine Composite signals combine

information encoded in more than one information encoded in more than one

cue; more potential for variation and cue; more potential for variation and

informationinformation

Ritualized DisplaysRitualized Displays

Common behavior patterns are Common behavior patterns are

exaggerated and simplified exaggerated and simplified

Body parts may be enhanced or Body parts may be enhanced or

colored in way that enhances the colored in way that enhances the

displaydisplay

Ritualization is often important in Ritualization is often important in

courtship displayscourtship displays

Illegitimate SignalsIllegitimate Signals

An illegitimate receiver intercepts a An illegitimate receiver intercepts a signal meant for individuals of signal meant for individuals of another speciesanother speciesTermite smells pheromone of invading Termite smells pheromone of invading

ant and attacks itant and attacks itAn illegitimate signaler mimics An illegitimate signaler mimics

signalssignalsPredatory fireflies mimic females of prey Predatory fireflies mimic females of prey

speciesspecies

Sexual Selection Sexual Selection

Reproductive success is measured in Reproductive success is measured in

number of offspring producednumber of offspring produced

Reproductive success can be enhanced Reproductive success can be enhanced

by increasing the number of matings or by increasing the number of matings or

the quality of mates the quality of mates

Male Reproductive StrategyMale Reproductive Strategy

Produce energetically inexpensive Produce energetically inexpensive

sperm sperm

Often provide no parental careOften provide no parental care

Often maximize reproductive success Often maximize reproductive success

by mating with as many females as by mating with as many females as

possiblepossible

Female Reproductive Female Reproductive StrategyStrategy

Produce large, energetically Produce large, energetically

expensive eggsexpensive eggs

Often provide parental careOften provide parental care

Often increase reproductive success Often increase reproductive success

by increasing the quality of their by increasing the quality of their

matesmates

Choosy FemalesChoosy Females

Female choice can dictate rules of male Female choice can dictate rules of male

competition and shape male behaviorcompetition and shape male behavior

Selects for males that appeal to femalesSelects for males that appeal to females

Male sage grouse display in leksMale sage grouse display in leks

Male hangingflies offer nuptial giftsMale hangingflies offer nuptial gifts

Male ContestsMale Contests

Females of some species cluster in Females of some species cluster in

groupsgroups

Males of such species may fight one Males of such species may fight one

another for access to harems another for access to harems

Selects for large males that can Selects for large males that can

defeat other males in contestsdefeat other males in contests

Parenting BehaviorParenting Behavior

Enhancing the survival of offspring Enhancing the survival of offspring

can increase parents’ reproductive can increase parents’ reproductive

successsuccess

Parental behavior comes at a cost; Parental behavior comes at a cost;

drains time and effort that could be drains time and effort that could be

spent producing additional offspring spent producing additional offspring

Benefits of Social Living Benefits of Social Living

Improved detection of predators; many Improved detection of predators; many

eyeseyes

Improved repulsion of predatorsImproved repulsion of predators

Musk oxen Musk oxen

SawfliesSawflies

Selfish HerdSelfish Herd

A group held together by self-interestA group held together by self-interest

Other members of the group form a Other members of the group form a

living shield against predatorsliving shield against predators

Individuals may compete for the Individuals may compete for the

safest spots; positions in the center safest spots; positions in the center

of the groupof the group

Dominance HierarchyDominance Hierarchy

Some individuals accept subordinate Some individuals accept subordinate

status to othersstatus to others

Dominant members have higher Dominant members have higher

reproductive success than subordinatesreproductive success than subordinates

Subordinates may do better over long Subordinates may do better over long

term than if they were on their own term than if they were on their own

Costs of Social Living Costs of Social Living

Increased competition for food, mates, Increased competition for food, mates,

and other limiting resourcesand other limiting resources

Increased vulnerability to disease and Increased vulnerability to disease and

parasitismparasitism

Risk of exploitation by other group Risk of exploitation by other group

membersmembers

Altruistic Behavior Altruistic Behavior

Nonbreeding helpers are found in Nonbreeding helpers are found in

mammals, birds, and insectsmammals, birds, and insects

Altruists apparently sacrifice their Altruists apparently sacrifice their

reproductive success to help othersreproductive success to help others

How are genes for altruism perpetuated?How are genes for altruism perpetuated?

Theory of Indirect SelectionTheory of Indirect Selection

Proposed by William HamiltonProposed by William Hamilton

Genes associated with caring for Genes associated with caring for

relatives may be favored by selectionrelatives may be favored by selection

Altruists pass on genes indirectly by Altruists pass on genes indirectly by

helping relatives who have copies of helping relatives who have copies of

those genes to survive and reproduce those genes to survive and reproduce

Social Insects Social Insects

Workers in colonies of social insects are Workers in colonies of social insects are

sterilesterile

These colonies are extended familiesThese colonies are extended families

Workers pass on their genes indirectly Workers pass on their genes indirectly

by helping relatives reproduceby helping relatives reproduce

TermitesTermites

Workers and soldiers are sterileWorkers and soldiers are sterile

A single queen and one or more A single queen and one or more

kings are the parents of the entire kings are the parents of the entire

colony colony

HoneybeesHoneybees

Workers are sterile femalesWorkers are sterile females

A single queen is the mother of all A single queen is the mother of all

members of the colonymembers of the colony

At certain times of the year, the At certain times of the year, the

colony produces drones--fertile males colony produces drones--fertile males

that leave the colony and matethat leave the colony and mate

Naked Mole-Rats Naked Mole-Rats

Only mammals known to have a sterile Only mammals known to have a sterile

worker casteworker caste

Single queen reproduces with one to Single queen reproduces with one to

three malesthree males

DNA evidence shows clan members are DNA evidence shows clan members are

all closely relatedall closely related

Considering Human Behavior Considering Human Behavior

Some human behavior may be adaptive Some human behavior may be adaptive

or may have been adaptive in the pastor may have been adaptive in the past

Testing hypotheses about human Testing hypotheses about human

behavior can help us understand how behavior can help us understand how

they arose they arose

Redirected BehaviorRedirected Behavior

Certain behaviors that are normally Certain behaviors that are normally

directed toward relatives may directed toward relatives may

sometimes be directed toward sometimes be directed toward

nonrelativesnonrelatives

In this case, the redirected behavior In this case, the redirected behavior

is nonadaptiveis nonadaptive

Human AdoptionHuman Adoption

Evolutionary theorists predict that Evolutionary theorists predict that people would be more likely to adopt people would be more likely to adopt related children than nonrelativesrelated children than nonrelatives

Studies have shown that in Studies have shown that in traditional societies this is truetraditional societies this is true

Adoption of nonrelatives may be an Adoption of nonrelatives may be an example of redirected behaviorexample of redirected behavior

Moral QuestionsMoral Questions

A behavior that is adaptive may or A behavior that is adaptive may or may not be desirable or moralmay not be desirable or moral

Some behaviors that were adaptive Some behaviors that were adaptive in small groups, such as adoption, in small groups, such as adoption, may no longer be adaptive in large may no longer be adaptive in large societiessocieties

A nonadaptive behavior may be A nonadaptive behavior may be socially desirable socially desirable