Wednesday, 20 October 2010

A change is gonna come

New Scientist has an interesting article on the complex workings of evolution. In summary - it's more complicated than people think. This shouldn't be big news, but the link with Monday's story on chaos theory was nice.

The author, Keith Bennett of Queens University in Belfast, likens the traditional symbol of the evolutionary process - the tree of life - to a fractal. The cumulative effect of iterative changes creating branching structures repeated at different scales throughout the whole. The relationship between microevolution and macroevolution is a controversial one, with a history of great scientific debate. Microevolution is the change of genetic traits within a species or population - perhaps a colour change in a group of birds' plumage for example - and macroevolution is the actual change from one species to another. For the most part I see one as a natural extension of the other, occurring over longer periods of time and having a more dramatic effect. Macroevolution can only come about through continual small changes.

Bennett is a palaeoecologist and suggests there are slightly different groups of driving factors behind the two scales of evolution, which may be the case to a point. If they are part and parcel of the same overall process, however, I'm not sure of the benefits of separating the two so distinctly, which he seems keen to do. The research behind the article points to a steady stream of speciation, reducing the influence of environmental change. He thinks macroevolution may be primarily driven by internally generated genetic alterations, rather than external influences such as climactic or habitat changes. To me, this slightly misses the point that the success or otherwise of any genetic changes are very often a result of how that modification affects an individual organism within its environment. If it brings it any advantage in terms of camouflage, feeding, breeding, survival in general, then that trait will be more likely be passed on to subsequent generations and gradually becoming widespread. If the environment is changing, then the efficacy of any mutation will be reflected in that to some extent. Environment may not be the main driving force, but it certainly plays a big role.

The main point of the article, I think, is that evolution is not predictable and any pattern we may see within developments are only discernible with the benefit of hindsight. It's a wonderful thing.

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