P.C. Shannon

I was just thinking the other day about how human civilization has effectively halted our evolution. Then I read this in Nature today (full article):

Icelandic scientists reported earlier this year, for instance, that 20% of Europeans carry a large genetic inversion that is spreading throughout the population. Women who carry the inversion have more children than those who don’t — a classic sign that it confers some sort of selective advantage.

It turns out that not only are we still evolving, but evolution may be more about large-scale rearrangements in the genome than changes in single base-pairs.

This reminds me of a presentation I saw a year or two ago about transposons in the rice genome. Transposons are these weird little pieces of DNA that exist in the genome. They are capable of jumping around the genome from place to place to place. Typically, they’re thought of as parasitic, although clearly they’re not organisms in their own right. They do nicely embody the idea of the “selfish gene” quite nicely.

The point of the presentation was the researcher’s assertation that transposons become active—that is, they jump around the genome a lot more—during periods of stress, and this increased activity promotoes evolution. The idea is that by stimulating evolution, the transposons make the host better able to deal with the stress, such as relocating to a colder climate.

It’s an interesting idea, although I’m not sure how many scientists buy into. But the notion from Nature that evolution involves reorganization of genome is certainly widespread, even though it upturns many long-held ideas about evolution and the very nature of biology. But this century has seen many such revolutionary ideas come to light. It’s an exciting time.