THE SKEPTIC?

The Domesticated Savage: Science reveals a way to rise above our natures (Michael Shermer, August 11, 2003, Scientific American)

One of the most striking features in artificially selecting for docility among wild animals is that, along with far less aggression, you also get a suite of other changes, including a reduction in skull, jaw and tooth size. In genetics, this is called pleiotropy. Selecting for one trait may generate additional, unintended changes.

The most famous study on selective breeding for passivity began in 1959 by Russian geneticist Dmitri Belyaev of the Institute of Cytology and Genetics in Siberia. It continues today under the direction of Lyudmila N. Trut. Silver foxes were bred for friendliness toward humans, defined by a graduating series of criteria, from the animal allowing itself to be approached, to being hand fed, to being petted, to proactively seeking human contact. In only 35 generations the researchers produced tail-wagging, hand-licking, peaceful foxes. What they also created were foxes with smaller skulls, jaws and teeth than their wild ancestors.

The Russian scientists believe that in selecting for docility, they inadvertently selected for paedomorphism--the retention of juvenile features into adulthood--such as curly tails and floppy ears found in wild pups but not in wild adults, a delayed onset of the fear response to unknown stimuli, and lower levels of aggression. The selection process led to a significant decrease in levels of stress-related hormones such as corticosteroids, which are produced by the adrenal glands during the fight-or-flight response, as well as a significant increase in levels of serotonin, thought to play a leading role in the inhibition of aggression. The Russian scientists were also able to accomplish what no breeder had ever achieved before--a lengthened breeding season.

Like the foxes, humans have become more agreeable as we've become more domesticated. [...]

A plausible evolutionary hypothesis suggests itself: limited resources led to the selection for within-group cooperation and between-group competition in humans, resulting in within-group amity and between-group enmity.

Well, yeah, except that the rational choices made by humans and applied to themselves and to silver foxes are actually the opposite of natural selection. Posted by Orrin Judd at August 30, 2003 7:01 AM