Tuesday, September 13, 2011

Yet another perspective on evolution

Consider this possibly true scenario:
Virus X lives inside 10% of the human population. It has integrated itself into the human genome, as many viruses do. It gets activated during the lifetime of a human and it exists the human body through the mouth and nose It is only able to invade other humans with specific proteins, which happens to be the same 10% of the population. In addition, this virus is also able to invade 10% of dogs and cats.
In the above situation, the virus X serves as a channel for DNA exchange. In other words, it is possible to build a "family tree" based on this virus. It is another a family tree based on a different means of reproduction. In normal reproduction, we do not reproduce our entire selves. Rather, some part of us is reproduced. Virus X is also reproducing a small part of us, and therefore, it is just like normal reproduction.

We think of the "tree of life" as a tree with lots of horizontal transfers. What if all these horizontal transfers actually form another tree of life, a tree that uses a different means of reproduction. Why limit to viruses? Microbes in our body are part of us. If microbes are mutating and being carried between species, then they, too, can be a means of reproducing a part of us. In summary, there might be several means by which we reproduce specific aspects of "us". Each of these means of reproduction can be used as a basis for building a different "tree of life". All these trees intersect.

So what is a species? It is basically a way of categorizing individuals. Just like there are different ways to classify books (e.g. language, subject, readers), there are different ways of classifying individuals. Each individual belongs in multiple species -- one for each type of reproduction process that affects the individual. We are all part of more than one species. So why do we give the regular form of reproduction so much importance? It's because of the brain, of course. The brain is not the master of our body. It is one component of the body, and just like any other component, it has roles. The brain is designed to pay attention to certain types of reproduction. For humans, these types of reproduction include sexual reproduction and cultural (meme) reproduction and maybe some other ones. We should not let the role of the brain affect the reality, which is that all of these forms of reproduction contribute significantly to natural evolution.

Therefore, natural evolution is a process where multiple trees of life are expanding and interacting. Individuals sit at the intersection points of these trees.