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A Brief History
of Sex
From Primordial Ooze to Evolutionary
Psychologists
Males
produce
sperm.
Females
produce
eggs.
Sex by Definition
Why have sex?
Asexual reproduction allows genes to
reproduce themselves exactly.
Sexual reproduction seems to serve
the species at expense to the individual,
which is contrary to Darwin’s premise.
The prevalence of sexual
reproduction cannot be explained
through genetics alone.
Sexually Avoiding
Diseases
Parasites are simple
and evolve faster than
we do.
Sexual reproduction
is insurance for
surviving future
diseases.
Sex is all about
compromise
Individual genes have an incentive to cheat
instead of playing nice during reproduction.
To avoid conflict and sabotage, the two
different kinds of sex cells evolved as a
compromise.
Male sex cells sacrifice the possibility of
passing on their organelle’s genes in order to
keep reproduction moving smoothly. They
specialize in being small and swift.
Cellular Sexism
Female sex cells
represent a larger
investment than
male sex cells.
Sexual practices
have evolved that
either reinforce or
offset this
asymmetrical
investment.
The Sex Life of
Males
gather
in
a
Peacocks
meat market called a
“lek”.
Females peruse the
males on display. The
best-looking peacocks
get nearly all the
females.
Result: evolution of
expensive beauty
The Sex Life of
Swallows
Males and females
form ostensibly
monogamous pairs.
Males try to keep
their females faithful
while pursuing discrete
affairs themselves.
The Sex Life of the
Preying Mantis
The female
frequently consumes
the male shortly after
sex.
Presumably, she is
more amply
compensated by the
additional nutrition for
furnishing the larger
sex cell.
The Sex Lives of
Sexual selection
Humans
clearly
helped shape
gender roles as we
know them today.
Analogies with
animals help us
theorize about the
process of sexual
selection.
However, our
understand is clearly