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Selection Forces on Humans
What
is the selection force that gives humans the best brain on earth?
Clearly,
early humans had a major selective advantage if they could occupy many niches, compete with other species for food, and avoid
becoming food for other species. Their better brains made these things
possible.
| Another somewhat frightening thing
to consider is that humans have always killed each other, sometimes
for food, but more often out of just plain meanness. No other species
does that against its own kind on the scale that humans have. All this
killing may have created selective forces for being smart because being smart
gives advantages in war. |
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But
humans also are smart enough to cooperate and work together to help
the species survive. Early hunter-gatherer cultures left plenty of evidence
that they worked as teams to find food. |
We
cannot be certain of the selective forces acting on humans today
because we can't look back from a million or so years from now. But let
us consider some possibilities:
- Worldwide
famine could act as a selective force that favors the survivors whose bodies used food more
efficiently or who were so aggressive that they took food resources
from the less fortunate.
- Worldwide
disease epidemics could favor people who were more resistant to
disease.
- Worldwide
pollution could favor people who resist the damaging effects of
environmental hazards (But remember, that cancer develops late in
life, after successful reproduction has occurred).
- World
war could favor people with traits that lead to success in war (such
as intelligence or aggressiveness).
Can
you think of others?
 
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