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Adaptations
Are:
built of existing variation (mutations).
often formed slowly
often formed cumulatively
specialized
costly
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may be out of date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.
frequency
Evolution by Natural Selection tends to make the
mean phenotype converge on the optimum.
trait value
frequency
Evolution by Natural Selection tends to make the
mean phenotype converge on the optimum.
trait value
frequency
Evolution by Natural Selection tends to make the
mean phenotype converge on the optimum.
trait value
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
frequency
trait value
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
Coffee
Men
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.