Monday, April 16, 2007

An especially egregious example...

...of something that greatly irritates Marco is the language used in this popular science article.

The thing that greatly irritates Marco- and me too, for that matter- is the pervasive image of evolution as a 'ladder' leading step by step to 'more highly evolved' beings. Nothing can be 'more highly evolved' in general. A species can be 'better adapted' for circumstances X, Y, or Z; but circumstances are subject to review (by climate change, giant asteroids, motorways, etc.).

One thing that confuses me is the relationship between population size and genetic change mentioned in the extract below. It seems counterintuitive. Perhaps a real biologist could help? :)

Zhang's team found that 233 chimp genes, compared with only 154 human ones, have been changed by selection since chimps and humans split from their common ancestor about 6 million years ago.
The result makes sense, he says, because until relatively recently the human population has been smaller than that of chimps, leaving us more vulnerable to random fluctuations in gene frequencies. This prevents natural selection from having as strong an effect overall.