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Misconceptions about natural selection
Because natural selection can produce amazing adaptations, it's tempting to
think of it as an all-powerful force, urging organisms
on, constantly pushing them in the direction of progress — but this
is not what natural selection is like at all.
First, natural selection is not all-powerful; it does not produce perfection.
If your genes are "good enough," you'll get some offspring into the next
generation — you don't have to be perfect. This should be pretty clear just
by looking at the populations around
us: people may have genes for genetic diseases, plants may not have the
genes to survive a drought, a predator may not be quite fast enough to
catch her prey every time she is hungry. No population or organism is perfectly
adapted.
Second, it's more accurate to think of natural selection as a process rather
than as a guiding hand. Natural selection is the simple
result of variation, differential reproduction, and heredity — it is
mindless and mechanistic. It has no goals; it's not striving to produce "progress" or
a balanced ecosystem.
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Evolution does not work this way.
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This is why "need," "try," and "want" are
not very accurate words when it comes to
explaining evolution. The population or individual does not "want" or "try" to
evolve, and natural selection cannot try to supply what an organism "needs." Natural
selection just selects among whatever variations exist in the population.
The result is evolution.
At the opposite end scale, natural selection is sometimes interpreted as a
random process. This is also a misconception. The genetic variation that
occurs in a population because of mutation is random-but selection acts on
that variation in a very non-random way: genetic variants that aid survival
and reproduction are much more likely to become common than variants that
don't. Natural selection is NOT random! |
