Tuesday, October 7, 2008

Human evolution over or speeding up?

"Compare and contrast..." goes the start of many an exam question. Well, in catching up on my reading of blogs and news media, I have just come across an interesting pair of articles, ripe for the compare-and contrast-treatment:
I will leave it to you the reader to work through the two articles and do your own "compare-and-contrast" assessment, but my own inclination is to side with Phelan rather than Jones on this. 

In fact, it seems odd that Jones is still publishing articles like this, because he has been making this point for a decade or more and this is nothing new in the Telegraph article. When  Jones first started saying human evolution is over, we were still in the history-is-over epoch, before 9/11, the Afghanistan and Iraq wars and the reassertion of Russian military and political power. 

Even back then, I found several problems Jones' argument:
  • It reeks of first-world complacency, when infant mortality is still so high in the Third World and populations are still being decimated by HIV, TB and malaria.
  • Even if the vast majority of people survive to reproductive age, the fact that even a small number do not is still enough to drive evolution. As Darwin said: "A grain in the balance will determine which individual shall live and which shall die, -- which variety or species shall increase in number, and which shall decrease, or finally become extinct."
  • Even if the vast majority of people survive to reproductive age, in an era of contraception and family planning, not all will have the same number of children. Any genetic difference that underlies this differential in reproductive success will still be the subject of natural selection. It’s a matter of speculation what affect fertility control will have on the human gene pool. When procreation is a matter of choice, rather than an inevitable consequence of passion, perhaps there will be a selective pressure for children to become steadily more manageable: if your first child is a terror, you might choose not to have any more! And conversely, whatever genes make people like children will be selected for!
  • If evolution is defined as any change in the frequency of alleles in the human gene pool, then lifting the selective pressure against what would, before modern society and medicine, have been deleterious genes or combinations of genes, then we are clearly in an era of massive evolutionary change. For example, is it really plausible that the rise in Caesarian sections is not having some effect on the distribution of genes underlying pelvic anatomy or determining the likelihood of other complications during labour?
Add to that the arguments in the Seed article and in the articles cited therein, and I see little or no cogency in Jones' arguments. I will leave the last word to Darwin:
“But Natural Selection, as we shall hereafter see, is a power incessantly ready for action, and is as immeasurably superior to man's feeble efforts, as the works of Nature are to those of Art.”
Additional reading:
Recent acceleration of human adaptive evolution, Hawks et al, PNAS
Not the end of evolution again! by John Wilkins on the Evolving Thoughts blog

1 comment:

Mark Pallen said...

see also: