Adaptations

Are:built of existing variation (mutations).often formed slowlyoften formed cumulativelyspecializedcostly

and:may be out of date

The Environment of Evolutionary Adaptedness (EEA)

Cognitive adaptations:

Not general-purpose fitness maximizer.

Rules of thumb:

Sex feels good, even with birth control

Masturbation feels good

Adoptive parents feel parental love

Emotional systems as internal rewards.

Evolution by Natural Selection tends to make the mean phenotype converge on the optimum.

trait value

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Evolution by Natural Selection tends to make the mean phenotype converge on the optimum.

trait value

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Evolution by Natural Selection tends to make the mean phenotype converge on the optimum.

trait value

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Sexual reproduction continually generates variation around the optimum.

Sexual Selection

Type of natural selection.

Selection builds adaptations of all types.

Sexual selection builds adaptations that increase mating success:

1. more mates

2. better mates

Selection builds adaptations that address recurring problems... faced by our ancestors.

Would the challenges of mate choice have been the same for ancestral males and females?

Theory of sexual selection says probably not.

Male reproductive success is less limited than female reproductive success.

Challenges for ancestral males: quantity.

Challenges for ancestral females: quality.

Likely to produce divergent adaptations:

Two optimal phenotypes

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Date solicitation experiment

Confederates asked unsuspecting subjects for a date.

Variable: coffee, apartment visit, sex.

Acceptance rate?

Date solicitation experiment

Confederates asked unsuspecting subjects for a date.

Variable: coffee, apartment visit, sex.

Acceptance rate?

Women Men

Coffee 50% 50%

Apartment 6% 69%

Sex 0% 75%

Evidence in favor of evolution

1.Existence and pattern of the fossil record.

2.Homology.

Evidence in favor of evolution

1.Existence and pattern of the fossil record.

2.Homology.

3.Universality of genetic code.

4.Analogy with plant and animal breeding.

5.Direct observation.