Thesis # 14 – Aging hypotheses based solely on supposed universal imperfections of molecular, cell, or organismal physiology are wholly falsified by the existence of biological species that do not exhibit falling average rates of survival and reproduction among large cohorts maintained under good conditions, a pattern exhibited by some fissile coelenterates, for example.
But there is no need for a Darwinian biologist to be particularly eloquent about the falsity of conventional gerontological theories. The images of the round Earth supplied by the NASA Apollo missions that reached the Moon obviously annihilate Flat Earth theory. Likewise, evolution has supplied devastating refutations of the cumulative damage theories of mainstream aging research.
Those refutations are the animal species that don’t show aging. At all. It is now a well-demonstrated fact of aging research that there are some animals which do not show a detectable increase in rates of dying with time, even after decades of maintenance. Under the best conditions, when extremes of temperature and predation are entirely prevented, along with provision of good nutrition, some of these animal species which reproduce by splitting into similar offspring can apparently be kept alive indefinitely. For example, sea anemones are species that grow as circular tubes with fringe tentacles. Some of these species reproduce by longitudinally splitting their fully grown tubes to make two smaller tubes growing side-by-side. Then the smaller tubes grow as large as their mother, and split again themselves. Animals like these have been kept alive in aquaria, without a single one dying, over many decades. Sea anemones are species of the coelenterate group. Coelenterates that reproduce in this fissile manner only do not usually show aging. Other coelenterates that do not have any type of fissile reproduction do undergo aging.
This contrast is shown by other animal groups, such as some aquatic worms. Plants with extensive fissile reproduction, like trembling aspen trees, also do not show aging. There is nothing whatsoever in the basic cellular or organismal biology of animals and plants that requires aging. Evolution by natural selection can entirely eliminate aging, regardless of each and every feature of cumulative biochemical or other damage that whole organisms and their cells might be subject to.
Exactly why and how evolution is able to accomplish this feat is a matter we will take up later in the 55. But for now, I suggest that you contemplate a somewhat similar feat. Each and every one of us is a collection of somatic cells that have branched off from a lineage of germ-line, or reproductive, cells that has been maintained for hundreds of millions of years, since the origins of the first vertebrates about 500 million years ago. Evolution has apparently had little difficulty accomplishing this feat for vertebrates, crustaceans, and mollusks, all of which we find ancestors for among fossils dating back more than 500 million years before the present time.
That is, there is nothing about the indefinite maintenance of lineages of cells that evolution has any difficulty accomplishing. Rather, things become different when well-defined somatic cells are produced, cells that will not become part of offspring. The reasons for this lie in the circumstances under which the forces of natural selection do not decline, as will be explained further here in the 55.