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kriton's Avatar Jump to comment 37 by kriton

Jos Gibbons, I am not sure what many of your questions are aiming for. Why do you ask "Such as?" when I discuss the conditions below? Or "Then what?" when the text continues below? Who are "they" in "Do they?" Same thing with "by what process do demes compete in this sense?" In what sense? And did you not in the sentence before assume that they do compete? And since I'm not a native English speaker, I do not understand the term "detracts from the scope". Could you phrase that in another way?

The equilibrium between competition and cooperation would be constantly changing, because new individuals are added to the mix and leaving the mix, and because other factors (food supply, competition from outside groups) change.

In a complex and changing environment there will be a large variety of challenges, and a single individual, or a group where everybody is the same, can not meet all these challenges as sucessfully as a diverse group. So the more complex and changing, the more likely that there could be an element of selection on the group level. This does not mean that selection on other levels is no longer important.

In my view, evolution takes place at several levels, and the importance of these levels have changed over time.

If we go back to the beginning of life, before cells, there probably was self-replicating molecules that can be compared to single genes. Then there was only the gene level, no genome level, and only or mainly competition.

But in a cell, for example a bacteria, genes are replicated together when the cell divides. The proteins coded for by genes have different functions and work together in the cell machinery. There is still competition on the gene level, but also cooperation. At the same time, there is competition on the genome level, since different bacteria compete with each other. If cells form colonies, then it would introduce an element of cooperation on the genome/individual level. Increased cooperation could lead to multicellular organisms, and then the epigenome would also become important.

An example of entities that still only work at the single molecule level could be prions, but cooperation in the form of cells was so effective that it came to dominate completely.

So there is a gene/protein level, a genome/individual level, and there could also be a gene pool/group/deme level. But only if cooperation gives a sufficiently large advantage will the action start trickling in into a higher level.

I'm not saying that group selection leads to a mixed equilibrium if there was not a mix there to begin with. There must first be a mix, for other reasons than group selection, and then the diversity of that mix can give a group an advantage if they stick together to a sufficient degree.

And "sufficient degree" brings us to Peter Grants post. Groups disperse, yes. But this is why I suggested in my previous post that group selection might perhaps only happen in humans. We have developed stuff that makes such group cohesion possible. Culture and, yes, religion. Now, a few thousand years is not a long time in evolution, but I never said the influence was big.

I think most readers do not know what is meant by deme, intraspecific or allelomorphic, so why not discuss the issue in an uncomplicated way that everyone can understand?

Sun, 22 Apr 2012 17:30:47 UTC | #936480