Monday, November 10, 2008

Evolution and development

Mark Blumberg is a professor at the University of Iowa and Editor-in-Chief of the journal Behavioral Neuroscience. He has written a book published by Oxford University Press called Freaks of Nature: What Anomalies Tell Us About Development and Evolution -- a gutsy topic.

Humans have always had an appetite for anomalies, and not so long ago "freak shows" were popular features at circuses and county fairs. Maybe they still are for all I know, but many of us today feel uncomfortable using the word "freak," especially as applied to human beings. I remember some years ago Life magazine did a photo essay on the Hensel twins, Abigail and Brittany, two lovely little girls who share one body -- in Barnum's language, a two-headed "freak." I looked at the photos with a mixture of primal fascination and embarrassment -- a complex and unworthy mix of emotions.

Blumberg begins and ends his book with Abigail and Brittany, unembarrassed. One can go to YouTube and watch a Discovery Channel show about the girls, who seem to be living remarkably ordinary and inspiring lives within a loving and supportive family. Their classmates appear to accept them as a matter of course. And that's what Blumberg is up to. Anomalies like the Hensel twins are alternate developmental paths that tell us much about the miracle and mystery of development -- how a fertilized egg turns into a human being -- and about the course of evolution that led to the present rich diversity of life on Earth. A human born without legs is a "freak." A reptile born without legs is a snake perfected by adaption. Writes Blumberg: "For in the larger, unfolding scheme of things, we are all extraordinary, all strange -- freaks every last one of us."

Maybe someday we will be able to pass Abigail and Brittany in the street without batting an eye, and maybe books like Blumberg's that normalize the "abnormal" will help. Still, the word "freaks" in the title seems to play into the very emotions the author would like to allay. P. T. Barnum got rich exhibiting anomalies -- what he might have called unfortunate rolls of the dice. Blumberg would have us understand that Abigail's and Brittany's anomalous anatomy is not the deliberate design of an inscrutable God, nor the result of blind chance ("There but for the grace of God..."), but rather the uncommon working out of the same biochemistry that has given us in the course of 4 billion years penguins, giraffes, duck-billed platypuses, snowy egrets, and all the other wonders of life on Earth.