THE RUNAWAY BRAIN

Remember the ``mitochondrial Eve'' (popularly interpreted to mean that we're all descended from an African mom upward of 200,000 years ago)? Remember Carleton Coon and the independent origin of the races of mankind? These are among the new and older ideas revisited in this wide-ranging review by Wills (Biology/UC San Diego; Exons, Introns, and Talking Genes, 1991). Essentially, Wills agrees with Stephen Jay Gould and others that evolution doesn't mean progress and hasn't stopped with Homo sapiens. What appears to be progress in our case, he says, is not a case of the uniqueness of human evolution, but of the evolution of human uniqueness. This has come about by interactions between the genome and the cultural milieu that have led to the feedback phenomenon of the ``runaway brain.'' Contributing factors include the narrowness of the birth canal, which ushers babies into the world at an immature stage, and personal interactions that facilitate the rapid growth and expansion of the brain, with its diverse systems and capabilities. To arrive at these conclusions, Wills summarizes the paleontological evidence, including the personae and controversies: He offers the corrective that the mitochondrial Eve might be much older and have had numerous companions who passed on their nuclear (as opposed to mitochondrial genes); he speculates that Homo erectus might have spread across the continents with all its apparatus in place to evolve to sapiens. Wills undergirds this argument with the latest findings from molecular genetics about the roles of duplicate genes and mutations with ``potential.'' Along the way, he finds time to discuss the origin of language, the brains of idiot savants (now called ``individuals with savant syndrome''), and the potential for human self- and planetary destruction. An impressive compendium of data and theories of human evolution, along with the author's own speculations—sure to trigger controversy in a field known for contention.