Bare Bones Biology 198 – Law of Life

Now you have watched Neil deGrasse Tyson’s second Cosmos show on the subject of evolution, in which he described the process of evolution by natural selection of domestic dog from wild dog or wolf. There is an equally elegant description in a National Geographic magazine, I think two years ago with a lovely color cover showing your favorite breed of dog – descended by artificial selection from some gene pool of early domestic dogs. These facts can be stated very confidently for several reasons, but one of the reasons is gene sequencing. Several groups of geneticists have been working to physically sequence the genes (that means find out what genes are present in which individuals, breeds and species, and in what sequence these genes are found in the nuclei of the cells. They construct pedigrees based on the genes.)

The direct line of inheritance can be confirmed in the dogs and other species that are being sequenced just as easily as they can be determined in humans. If you believe in genetics or in genetic engineering or in mutations or in treating genetically caused ailments, then you must believe in evolution, because the evidence is as clear as your own family tree.

120110-tree-_DSC2280L2SsHowever, as I said last week, Dr. Tyson did not present the graduate course in evolution, but the basic description of how evolution works today and has worked over the history of Life on Earth. In a very general way, evolution operates by natural selection, or artificial selection, for traits that are useful to a species. A species is all the organisms of the same kind. This does not mean that evolution IS “survival of the fittest,” as so many of us have proclaimed in our modern age –trying to believe that we are the fittest.

So what is evolution really? I have said it is the process of change in the gene pool over time. That is true, but not very helpful because it doesn’t explain how or why. Darwinian theory would suggest that the change in the gene pool is caused by six basic biological realities that are always present in all life forms:

1. The physical and behavioral characteristics of organisms are caused by their genes. Actually they are also caused by various accidents and experiences. The percentage of characteristics that are caused by inheritance, by the genes, is known as the heritability. Most often it is more than 50%.

2. No two organisms are genetically identical unless they are identical twins. Therefore the vast majority of organisms are somewhat different from each other in their physical and behavioral characteristics. First there is a very small, probably constant, rate of mistakes when the genes are copied to make the eggs and sperms; second, the process of making the eggs and sperms specifically causes the genes to recombine so that the genes come together in new combinations, creating a constant source of genetic variability. So everyone is a little bit different – even trees and bugs.

3. More offspring of all species are produced than can survive. If all the individuals of a species do survive, then the species will die out, because it will eat up all the available food and starve. That is not “fittest.”

4. If the species does survive, then the genes of those individuals do survive may be passed on to the next generation. You may call that fitness if you wish, but if you insist on doing so, you need to study the facts and discover that it is rarely the dominant, chest-pounding male that survives best, although occasionally one of them passes along an unusually large number of sperms – more likely the clever and nurturing female will provide both the genetic and the behavioral traits that most influence the survivability of the following generation.

5. The most important fact of Life that we must realize if we care about the future is that no individual organism evolves. Many organisms can learn, and human organisms can pass on that learning, but we are born with the physically heritable traits that we have and we cannot change our genetics.

6. No species evolves in isolation. Not dogs, not humans, not trees nor bugs. All the species in the Biosystem affect all the other species in small or large ways, and the ENTIRE BIOSYSTEM is a living unit, just as your body is a living unit – therefore – EVERYTHING evolves together with everything else in the Biosystem. It does NOT evolve according to human values. Most of the species are not human. The Biosystem and all the species evolve together according to the natural laws that permit life to exist on earth.

The function of the natural Law of Evolution, the basic Law of Life, is to maintain a viable BALANCE among all these factors at all the many levels of the Life on Earth.

So let’s get that fitness soundbite out of our heads and figure out how evolution really works so maybe we might actually survive.

This is Bare Bones Biology, a production of FactFictionFancy and KEOS Radio, 89.1, Bryan, TX. A copy of the podcast may be downloaded at:

This blog and two upcoming blogs are written in response to a question asked by Gary Gripp and two questions asked at the Monday Lunch group. Good questions are most helpful; otherwise – how can we discuss the issues?

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