Tuesday, May 24, 2005

Evolution of Behaviour

Here is the definition of a species from Wikipedia. Now, whilst a species can be defined in terms of its appearance/characteristics, and its ability to reproduce only with other members of the species, the behaviour of a species can also be characteristic. There are certainly many behaviours that are “instinctive” - that don’t appear to be taught – although there are others that are taught. Courtship behaviour, for example, is “instinctive”, whereas I understand hawks teach their young to hunt prey (though presumably this teaching of the young is “instinctive” - simply regressing one level – nobody comes along and tells the mother hawk it’s time that the children learnt how to feed themselves)

The issue: is this species-characteristic behaviour part of the genetic heritage of the species? The answer to this question leads to further lines of questioning.

If no, then where did it come from originally? How is it passed on from generation to generation? How is it modified as, in evolutionary terms, a species changes over time?

If yes, then given that we have inherited genetic material from ancestors, we ought to have inherited their behaviour as well. There has been some discussion about the fact that there are genes that are no longer expressed in higher organisms that were more important to their ancestors. Are there genes that would have controlled the instinctive behaviour of these ancestors? If not, then how come they have been discarded through evolution? If so, then what would be the effect of these genes being expressed in a higher organism?

I have kicked off a thread on the ARN bulletin board with this posting.

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