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Nature Nurtureversus

All behavior is the product of an inextricable interaction between heredity and environment

during development, so the answer to all nature-nurture questions is “some of each.”

-Steven Pinker

What determines a particular phenotype?

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5/15/08: Development of BehaviorLecture objectives:

1. Understand that behavior is a product of gene-environment interactions

2. Be able to figure out whether differences in a behavior arise from genetic and/or environmental differences

3. Understand features of development and the adaptive value of learning

+

Behavior 1

Behavior2 ? ?

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Behavior is a complex product of gene-environment interactions

Environment influences expression of genes

(protein production)

Development unfolds over time

Genes encodeinformation

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Example (pgs. 56-59): Gene-env interactions underlie the development of honeybee foraging

Effect of social environment:When foragers (old bees) are scarce, young bees will rapidly become foragers

Nurse(young)

Forager(old)

Gene 1Gene 2Gene 3

.

.Gene n

Nurse(old)

Forager(young)

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Example cont: Gene-env interactions underlie the development of honeybee foraging

nurse forager

Concentration of JH

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Even learning has a genetic contribution

Example: Different species show different imprinting tendencies

Learning

Gene-environment interactions

Blue tit Great tit

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Nature Nurtureversus

All behavior is the product of an inextricable interaction between heredity and environment

during development, so the answer to all nature-nurture questions is “some of each.”

-Steven Pinker

X

Info in genes is only expressed Development & learning require the

What determines a particular phenotype?

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Lecture objectives:

1. Understand that behavior is a product of gene-environment interactions

2. Be able to figure out whether differences in a behavior arise from genetic and/or environmental differences

3. Understand features of development and the adaptive value of learning

+

Behavior 1

Behavior2 ? ?

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Members of the same species often differ in behavior

What underlies differences in development/behavior?- differences in genetic info?- differences in environmental inputs?- both?

Black-capped chickadee:

caching behavior

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Differences in development/behavior can arise from environmental differences

Idea:

Environment A

Environment B

Behavior/Phenotype 1

Behavior/Phenotype 2

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Example: social behavior differences in paper wasps arise from early olfactory experiences

I don’t fight with my sisters!

Can experience shape a wasp’s tendency to tolerate unrelated wasps (nonkin)?

Home nest Foster nest

Tendencyto fight

Sisterwasps

Fosterwasps

Sisterwasps

Fosterwasps

Demonstrated by manipulating

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Differences in development/behavior can arise from genetic differences

Idea:

Behavior/Phenotype 1

Behavior/Phenotype 2

Genotype A

Genotype B

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Example: “Good mommy” behavior differences in mice arise from genetic differences

Demonstrated by a

fosB

fosB Expression is “knocked out”

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Example: Slug-eating behavior differences in tiger snakes arise from genetic differences

Demonstrated by a

X

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Example: Cotton collection differences in mice arise from genetic differences

Demonstrated by an

x

x

x

?

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You suspect that the difference in food-caching ability of these two bird populations has a genetic basis, but there hasn’t been much work done on this question before. You only have 2 years of funding for the project. How will your research team go about investigating this question?

1. Come up with a project plan that seems feasible – write/draw your experimental design2. List why you chose that design over the other possible designs you could have chosen3. List your predictions for the hypothesis that the trait difference has a genetic basis

Black-capped chickadee:

caching behavior

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Lecture objectives:

1. Understand that behavior is a product of gene-environment interactions

2. Be able to figure out whether differences in a behavior arise from genetic and/or environmental differences

3. Understand features of development and the adaptive value of learning

+

Behavior 1

Behavior2 ? ?

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“Normal” development is often robust, even under adverse genetic or environmental conditions

Gene knockouts

Genetic system likely has high

informational redundancy

Rhesus monkeys develop normal social behavior with only

15 minutes of socialization/day

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Sometimes there is more than one form of “normal” development ( >1 discrete phenotype)

Proximate: what env. cues activate a different developmental pathway?

Ultimate: what fitness benefits do animals gain from being able to “choose” how to develop?

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There are costs and benefits to learning

Costs: Benefits:

Adaptive modification of behavior based on experience

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Natural selection favors investment in learning when the ability to learn confers reproductive advantages

Benefits > Costs

The ability to learn would probably be beneficial for male thynnine wasps.

Yoohoo! Where is my Romeo?

Something isn’t quite right here…

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An animal’s ability to learn certain associations or solve certain problems often makes biological sense

Example: Rats have an easy time learning certain associations and a hard time learning others

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An animal’s ability to learn certain associations or solve certain problems often makes biological sense

Example: Sex differences in spatial learning ability are linked to home range size

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Summers' remarks on women draw fireBy Marcella Bombardieri, Globe Staff | January 17, 2005

“The president of Harvard University, Lawrence H. Summers, sparked an uproar at an academic conference Friday when he said that innate differences between men and women might be one reason fewer women succeed in science and math careers. Summers also questioned how much of a role discrimination plays in the dearth of female professors in science and engineering at elite universities.”

What is your reply to the following assertions? Explain your answers.

• Genes determine the ability of women to succeed in science.• Upbringing and culture determine the ability of women to succeed in science• Differences in the abilities of men and women to pursue scientific careers

might arise from genetic differences• Differences in the abilities of men and women to pursue scientific careers

might arise from cultural differences• There is a gene or group of genes that determines scientific ability.