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| Charles Darwin |
Since Charles Darwin coined this term, and included it in the title of his famous book, published in 1859, the term natural selection has been poorly understood, especially by non-specialists. Let’s review a few of the most frequent mistakes:
- Natural selection is a force that acts on living
beings to cause evolution. This is not true. Natural selection is not a force, nor an object, nor
an interaction, nor a phenomenon. It is simply a statistical observation. What
is observed is the fact that, in general, individuals better adapted to
their environment tend to leave more descendants than those less adapted.
Nothing else. It is, therefore, a matter of common sense, not the result
of the external action of a mysterious force.
- Natural selection directs evolution to follow progressive paths that lead, for
example, to the single toe of the horse, the trunk of the elephant, the
neck of the giraffe, or the brain of man. This misconception was
widespread during the second half of the 19th century, but it is not true.
Natural selection (a statistical finding, remember) does not direct
evolution. Artificial selection (on which Darwin relied to arrive at the
concept of natural selection) does not direct the evolution of our
domesticated animals and plants. Man directs this evolution, using
artificial selection as a procedure.
- Natural selection favors the survival of species
of living beings. This is not
true. Natural selection does not apply to species, but to individuals. The
biologist Jonathan Silvertown expresses it in this way in his book The
Long and the Short of It: The Science of Lifespan and Aging:
[N]atural selection does not work for
the good of the species, but instead works on individuals, favoring those whose
inherited traits cause them to leave the most descendants. Natural selection for individual
advantage trumps any alternative that would involve a sacrifice purely for the
good of the species. To see why this is so, imagine a population in which old individuals
sacrifice themselves… for the good of the species. Sooner or later a mutant would
appear with a defective gene for self-sacrifice. By living longer, this mutant
would be able to leave more offspring than any
self-sacrificing individual, and in just a few generations self-sacrifice
would go distinctly out of fashion.
So where does altruism come from? It exists, especially in
social species, abundant among insects, birds and mammals. In a
previous post I talked about theories that try to explain the altruism of
hymenopteran insects without giving up the idea that, if a character has
appeared and been selected, it must be useful to ensure the reproduction of the
genome of the individuals that form the colony, which functions as a higher
order organism. In any case, as Silvertown points out, this has nothing to do
with conservation or the good of the species.
The case of man is
completely different. At first, altruism could favor the survival of the genome
of the extended families that made up primitive tribes. But as the size of
human societies grew, altruism expanded thanks to the intervention of an
element that did not exist before the appearance of man: the ethical
requirement, which can be expressed with the golden rule: Do not do unto others what you don't want done unto you. Do
unto others as you would want them do unto you.
Unto others; to
every human being. Or to the human species, and this requirement can
even be extended to cover other species of living beings. But it is a totally
new idea, unique to man. Throughout the history of evolution, no living being,
microorganism, animal or plant, has ever set itself the goal of the survival of
its species. Neither explicitly, because they don’t even have the concept of
the species; nor implicitly, because natural selection does not favor the
survival of the species, rather favors the survival of the genome of certain
individuals, even to the detriment of others belonging to the same species.
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