behavior, part 1

Behavior

What organisms do

37.1-8, 10-12

39.1-8, 10-12

Behavior is shaped by evolution, like physical traits

Behavior is also flexible enoughto change with the environment

Behavior is widespread

Proximate Cause

Genetic or physiological mechanismfor a behavior

Ultimate Cause

Evolutionary, adaptive cause for a behavior

Human taste and food choice

Proximate causesWhat regulates hunger cravings?

Ghrelin

a hormone that stimulates hungerproduced by cells in the stomach and pancreas

Ghre

lin leve

lTime of day

increases before meals and decreases after meals

Pleasure

Dopamine

Ultimate causes:Why did we evolve to like certain

foods?

Sodium (mg) 700 2300-6900

Late Paleolithic Contemporary American

Amount of Sodium in Diet

Proximate cause

Hormones trigger pleasure in our brain

when eating certain foods

Ultimate causeHumans evolved to prefer salty food

in a low sodium environment

Nature vs Nurture

Nature:- Instinctive/Innate Behaviors- Behavioral Genetics

Fixed Action Pattern fixed response to a stimulus

KonradLorenz

Stimulus: egg outside of nest

Fixed Action Pattern: roll into nest

Stimulus: egg objectoutside of nest

Fixed Action Pattern: roll into nest

Most behavioris not fixed, but can still have a genetic basis

fosB gene controls maternal care in mice

Mutant fosB allelle Normal fosB allele

38

Twin Studies

Studies of identical twins show strange behavioral coincidences:

“Springer and Lewis found they had each married and divorced a woman named Linda and remarried a Betty. They shared interests in mechanical drawing and carpentry; their favorite school subject had been math, their least favorite, spelling. They both had sons whom one named James Alan and the other named James Allan. And they both owned dogs which they named Toy.”

University of Minnesota twin study, Bouchard et al

Studies of identical twins show strange behavioral coincidences:

“Oskar was brought up Catholic in Germany and joined the Hitler Youth. Jack was raised a Jew and lived for a time in Israel. Yet they had similar speech and thought patterns, similar gaits, a taste for spicy foods and common peculiarities such as flushing the toilet before they used it.”

MAOA “warrior” gene

MonoamineOxidase A

Enzyme breaks down neurotransmittersin the brain (including adrenaline)

People with an allele for low MAOA activity tend to respond more aggressively when provoked

Nurture:Learning

Learning:from simple to complex

Habituationrepeated stimuli produce weaker responses

Sensitizationrepeated stimuli produce stronger responses

Classical Conditioning

associating behavior with a new stimuli

Operant Conditioning

Associating behaviorwith a reward or punishment

Imprinting

Filial Imprinting:offspring form innate social attachments

Cognition

Can non-human animals think?

Naturevs Nurture

Naturevs andNurture

White-crowned sparrow (WCS)

• Normal song

• No song

• Wrong song

In lab experiments, newly hatched WCS maleswere played:

Song sparrow song

Peter Marler’s research

• Normal song: sang correct song

• No song: sang poorly developed version of WCS song

• Wrong song: sang poorly developed version of WCS song

In lab experiments, newly hatched WCS maleswere played:

MAOA “warrior” genePeople with low MAOA activitywho experienced a traumatic event as a childwere more likely to exhibit antisocial, violent behavior as adults

People with low MAOA activity who did not experience a traumatic eventwere not any more likely to be violent than control groups