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May 14, 2003

EVOLUTION OF COMPLEX FEATURES

There's an important article in this week's 'Nature' (8 May) on 'The Evolutionary Origin of Complex Features', by R. Lenski et al. (Nature, vol. 423, pp.139-45).

The authors use a computer simulation of the evolution of complex logic functions from simple elements, using proxies for 'mutation', 'fitness', etc. The technical details are beyond me, but it looks like good stuff. The general result is to show that highly complex 'adaptations' can indeed emerge by natural selection. It is possible to trace back in detail how adaptations have emerged, and then re-run the simulation with alternative options. One of the interesting findings is that occasionally mutations that are initially disadvantageous can still be established by selection, either because they 'hitch-hike' with linked advantageous 'genes', or because they are quickly followed by mutations elsewhere in the 'genome' which have an advantageous epistatic effect. It's not clear how realistic this is in biological terms, but it could happen, and it is allowed for in Sewall Wright's 'Shifting Balance' model.

Back to 'culture' in my next post.

DAVID BURBRIDGE

Posted by David B at 03:13 AM




I dunno about this whole evolution thing. I wanna hear more about POLITICS!

Posted by: President Bush at May 14, 2003 07:39 AM