Monday, 24 January 2011

Evolution without natural selection

I find the idea that evolution is possible without natural selection fascinating!

Suppose that there is a fixed number of species with equal number of male and female and exactly the same length of life for all species. Each pair produce two offspring male and female keeping the perfect balance of the whole population. Now is the question: is evolution possible in this scenario? One answer is no, because there are no natural selection and no preference is given to one carrier of genes before another.

If genes are taken from the parents in exactly random way then each parent pair pass 75 per cent of their genes to their offspring, because it is 50 percent from each parent to each child, so 25 percent is shared between two offspring. It means that with each generation a quarter of all genes are lost. However due to genes variety and enough repetition within the whole population, the number of distinct genes may not be decreasing. If there are random mutations in genes the variety can increase. In the other case when passing genes is not fully random, less than 75 per cent is being passed, so the washing out of genes is even faster.

Suppose however that there is a mechanism which marks genes of the individual as better or worse. If two genes one from each parent fight for the place to be in the descendant based on their marked value, then better genes are passed to the next generation and worse genes will be lost. In this case the natural selection happens on the level of genes and not on the level of species. Overall trend is that each generation has better genes even that no preference is given to any creature during its life.

Obviously there are two questions here. First what is that mechanism which makes genes to be marked and compete? And second, what means a better gene? Or in other words, how the organism decides which gene to reward and which to punish? Let them to be open. What is interesting is that evolution happens in a completely perfect and stable environment for species.

If something like this happens in reality, the main reason for this probably is the elimination of undesirable mutations in genes.

Thursday, 13 January 2011

On Memory

You know what is memory. It is in your memory. But what is it? It is defined vaguely as 1) something remembered; 2) preserved data for retrieval. How do I know that someone has memory? It is simple - if his behaviour adequate to his past experience. But what if that someone does not reveal any behaviour? In such case to assert that the memory exists is problematic. In the simplest case the memory is a table device with input and output entries. For any particular input the device manifests output. In a computer, memory input is the address of a memory cell and output is the value stored in the memory cell. Note that in computer computation it is important that the addresses in memory are associated with each other by arithmetic operations; otherwise no useful computations would be possible.

Behaviour or output is necessary in memory definition. If no behaviour present (for example one cannot extract values from the memory) then it does not matter whether a device has anything in its memory or not. For an external observer memory is not present.

Time is necessary for memory definition. Memory links two events distant in time. And the opposite is true, if two events distant in time are linked, then there memory exists.

Space is required for memory associations. Different memories can be liked in space by association. In other words memory about memory maps time link into space link. The most interesting thing here is that mapping back space link into time link can be done arbitrary by a device. For example time can shrink or be reversed. In the first case, the device reveals ability to predict and in the second to infer.