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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