Cultureplaces

The New York Times June 26, 2007 By NICHOLAS WADE Historians often assume that they need pay no attention to human evolution because the process ground to a halt in the distant past. That assumption is looking less and less secure in light of new findings based on decoding human DNA. People have continued to evolve since leaving the ancestral homeland in northeastern Africa some 50,000 years ago, both through the random process known as genetic drift and through natural selection. The genome bears many fingerprints in places where natural selection has recently remolded the human clay, researchers have found, as people in the various continents adapted to new diseases, climates, diets and, perhaps, behavioral demands. A striking feature of many of these changes is that they are local. The genes under selective pressure found in one continent-based population or race are mostly different from those that occur in the others.These genes so far make up a small fraction of all human genes.

(AP) -- Children at the top of the pecking order - either by birth or because their older siblings died - score higher on IQ tests than their younger brothers or sisters. The question of whether firstborn and only children are really smarter than those who come along later has been hotly debated for more than a century. Norwegian researchers now report that it isn't a matter of being born first, but growing up the senior child, that seems to result in the higher IQ scores. Petter Kristensen and Tor Bjerkedal report their findings in Friday's issue of the journal Science . It's a matter of what they call social rank in the family - the highest scores were racked by the senior child - the first born or, if the first born had died in infancy, the next oldest. Kristensen, of Norway's National Institute of Occupational Health, and Bjerkedal, of the Norwegian Armed Forces Medical Services, studied the IQ test results of 241,310 Norwegians drafted into the arm