Re: Sociobiological Concepts

From: Stevan Harnad (
Date: Sat Oct 11 1997 - 21:40:51 BST

> From: Rebecca dale
> An Evolutionary Stable Strategy is a strategy which, if
> most members of a population adopt it, it cannot be
> bettered by an alternative strategy. (Dawkins!) I am not
> very sure on this concept but will try to give an example.
> Suppose a male bird fertilises a female and chooses a
> nest. Whilst the male must then provide food for the new
> born chicks, to maximise his genetic output, he fertilises
> another female (secondary female) who has already nested
> with another male close by (obviously while the male is
> out of sight). This strategy has several advantages: the
> two nests are close by so he can feed both easily; if one
> batch dies, he has secured his genetic output, if he did
> fertilise the secondary female, her mate may unknowingly
> provide food for her new born chicks. Male birds which
> choose just one mate will not be as successful because
> they may be finding food for someone else's chick!

Not quite: You have just described a trait that might or might not be
adaptive. The idea of an ESS comes from game theory:

It is always based on competition. A strategy is stable is one that
cannot be bettered (invaded) by another strategy. Find more
examples here:

It's risky making up your own examples, because in general the stability
of an ESS is not obvious. It must be calculated by thinking over all the
possibilities, perhaps even simulating them on a computer, to show why
a strategy is stable and cannot be "invaded" by a rival strategy.

Other web links I came across that explain some of the concepts we are

This is a summary of the Selfish Gene:

This is a glossary of biological terms:

Here's yet another one:

Ry an altavista search of your own:

If you look at this message in the Skywriting archive, you will
be able to reach all the above sites by just clicking on them

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