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kriton's Avatar Jump to comment 47 by kriton

Let me add one more thing: It's important to remember the difference between selection and evolution.

Evolution is a very long-time process that contains a very large number of mutation and selection events. Selection does not have to be a process that includes mutation.

Suppose population a has gene X and population b gene Y instead. They are geographically separated. But land rise or the meltning of a glacier or something else creates a passage. Population a invades and outcompetes population b in 50 years. No significant mutation occurs in this time window, but it's still selection (on the gene level).

If we are talking about group selection, but not group evolution, the timescale doesn't have to be a problem. Now, two more examples.

1: Two human groups, each has its own religion that make members avoid infidels in other groups. Group a has gene X and group b has gene Y. Gene X give individuals some advantage in combat. Group a crushes group b in battle and then do things the Joshua way. This is NOT selection on the group level, but the more fit gene has won.

2: Two human groups, each has its own religion that make members avoid infidels in other groups. Group a has members with gene X, gene Y or gene Z. Group b has members with gene U, gene V or gene W. Now, a group of individuals with genes X, Y and Z can defeat a group with genes U, V and W in the long run, but only if all three types are present and working together in the group. This diversity has arisen because of other reasons than group selection, on the gene level.

Group selection is now possible because I) the diversity that is already present is such that it can give an advantage, and II) the group is made stable because of the religion.

Sun, 22 Apr 2012 22:39:16 UTC | #936542