A Difficult Question for Natural Selection

Yesterday I blogged about Dick Teresi’s new book, The Undead. Whatever you might think about his conclusions—legitimate or fantastical, researched or irresponsible—it is an interesting read.

The author raised one question of evolutionary biology that was particularly helpful: if “the beauty of natural selection is that species select for traits that increase their chances of survival and select against those that decrease their odds of survival” (28). why are there no immortal species? After all, “what could be more advantageous than a species that evolved a better technique of copying telomeres, or whatever it is that would eliminate death?” (29).

Among the biologists to whom he addressed this question, only one gave a response. Dr. Theodore Sargent “said that immortality would pose some problems:

  1. “An immortal population would be predominantly old and at a disadvantage whenever youth was favored.
  2. “Longevity might give some competitive advantage in the short term, but the immortal population might be unable to take advantage of sexual reproduction, which provides diversity, to survive climatic shifts and other disasters in the long run.
  3. “The old might squeeze out the young—’if only because of physical limits to the numbers of organisms that can occupy a given space.’ Sargent went on to say that this could lead to what demographers refer to as a ‘senile, declining age-distribution’ profile, that is, weighted toward the ‘old’—like the United States today” (29).

Here is Teresi’s response:

Each of the arguments against the advantage of ‘not dying’ is teleological, which is to say goal-oriented. . . . Something that is teleological is thus directed toward a definite end or has an ultimate purpose. It requires natural selection to be godlike, to be able to predict the future. Natural selection is supposed to be a simple matter of random mutations. Most of those mutations are harmful to the organism, but in rare cases an advantageous mutation occurs, say, a curved beak that allows a bird to dip into a flower for nectar or a flatter tail that provides a beaver with speed and mobility. Those mutations are selected for, goes Darwin’s respected theory, and become commonplace in a species, helping it to survive. A curved beak might one day become a disability, but natural selection has no way of knowing this. Natural selection is like a desperate corporate CEO, worrying about third-quarter profits only and not thinking about ruination down the road (29–30).

The author concludes with Jean-Paul Sartre that “if God is dead, it leaves a God-shaped hole in the universe. People fill that hole with whatever’s handy, and in the case of many modern biologists, they fill it with natural selection, a godlike causal process that we hope will explain all of life’s mysteries, including death. We may be asking too much of natural selection, which has plenty to do making beaks bend in the proper direction” (30–31).

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2 Responses to A Difficult Question for Natural Selection

  1. Adam Benton says:

    For most animals, immortality would be no benefit. Predators, disease, famine etc. would’ve killed them long before heart disease. As such, they would experience very little selection pressure for immortality.

    This is further compounded by the fact that there is a limit on reproductive age in women. As such, any extension of life beyond that would confur no reproductive benefits, again reducing the pressures of natural selection to make one immortal.

  2. Pingback: A Difficult Question for Natural Selection | Peter Beninate

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