Reply #61: Humans still evolving at a "breakneck pace"

[ultraist]

excerpts
http://www.handprint.com/LS/ANC/hfs10.html
Hominds seem remarkable for the sheer diversity of the fossil record. No other mammal has spread over as large a geographic and ecological range, nor evolved so many new forms of behavior within just a few million years.

The origins of this variability are behavioral as well as genetic. As human acestors evolved, accumulating hominid technology gave our biological variability an accelerating push. But before technology could have much impact, our evolution was also helped along by the human tendency to migration and the resulting geographic isolation of different hominid groups -- documented in Hominid Fossil Sites and Patterns of Homind Dispersal.

Separated in space, hominids evolved into regional variants that are sometimes treated as different species. Genetic variability within hominid species, and uncertainties in fossil reconstruction or geological dating, make these distinctions controversial. They are also somewhat beside the point: early humans were a restless species evolving at a breakneck pace.

The extreme reduction in size of the jaw across human evolution, along with its corresponding shift under the skull, has had an impact on human dentation -- particularly in the frequency with which humans show irregular or misaligned teeth. Even within the last 50,000 years, a trend toward smaller teeth and bone mass is apparent. The face, jaw and teeth of Mesolithic humans of 10,000 years ago were about 10% more robust than those of modern humans; Upper Paleolithic humans of about 30,000 years ago were about 20 to 30% more robust. Even among modern humans, the smallest tooth sizes are found in those areas where food processing techniques have been used for the longest time. Thus, right up to the present, evolution has continued to adapt humans to their ever-changing technological environment.