The Collective Radiation Exposure

I saw an announcement of a celebrity look-alike contest, and an idea began to develop in my mind.

Our appearance is determined primarily by our genes. Racial differences, particularly skin tone, are mainly from exposure to the sun, but the sun does not otherwise have a great effect on our genes. We can see that people with dark skin do not look any more different from one another than do people with light skin.

The sunlight to which we are exposed is highly directional. In contrast, cosmic rays bombard us in roughly equal amounts from all directions in space. Except for racial differences, especially the skin, variations in what we could call our "non-racial form" come about from changes in the genes brought about by these penetrating cosmic rays.

Minor differences in appearance are also caused by large-scale inbreeding. Whenever there is any type of boundary; whether physical, political, religious or, linguistic, it becomes more likely that anyone on one side of the boundary will most likely marry someone on the same side of the boundary. Over long periods of time, this tends to cause people on each side of the boundary to develop different random physical features.

For most of the time that human beings have lived on earth, there have been relatively few people. This has changed only very recently, relatively-speaking. The introduction of potatoes from the new world was one of the factors that made possible a major increase in the population of Europe. There were around one billion (thousand million) people in the world in 1850, now there is seven times as many. There were certainly few people in pre-historic times, before civilization and agriculture. It is believed that there were maybe two hundred million people in the world around the time of Christ.

The concept of the "Collective Radiation Exposure" that I have arrived at is that this is the total potentially gene-altering cosmic rays that humans, as a whole, have ever been exposed to. This exposure only makes a long-term difference during the time before the people have finished having children.

If we make a graph of the increase in human population from the beginning of human beings until now, it will be easy to see how humans, as a whole, have been exposed to only a small fraction of the cosmic radiation that can alter genes that we would have been if the population had increased at a steady rate from the beginning to the present polulation. This is simply because human population increased very slowly until it underwent a sharp increase, and multiplied many times, in relatively recent times due to advances in medicine and a reliable food supply. About one in every nine people that have ever lived are alive today.

If the human population had increased at a steady rate to what it is today, humans would have been collectively exposed to many times the amount of radiation, and people would now look much more different from one another than they do. Humans have been exposed to so little gene-altering radiation, in comparison with how many people there are in the world today. The result is that many people look like other people, and we can have celebrity look-alike contests.

Genes are finite, and do not have unlimited potential for variation. There is a certain maximum range of genetic variation, regardless of the Collective Radiation Exposure. This principle affects all living species, not just humans, and facilitates adaptation.

Just imagine all human beings as a vast collective antenna, receiving the cosmic rays which continuously bombard us from all directions in space, and which can penetrate and alter our genes and cause random variations in our appearance.