>Wed Mar 24, 6:45 PM ET
>
>By JOSEPH B. VERRENGIA, AP Science Writer
>
>Touching off a scientific furor, researchers say they may have
>discovered the mutation that caused the earliest humans to branch off
>from their apelike ancestors — a gene that led to smaller, weaker jaws
>and, ultimately, bigger brains.
>
>Smaller jaws would have fundamentally changed the structure of the
>skull, they contend, by eliminating thick muscles that worked like
>bungee cords to anchor a huge jaw to the crown of the head. The
>change would have allowed the cranium to grow larger and led to the
>development of a bigger brain capable of tool-making and language.
>
>The mutation is reported in the latest issue of the journal Nature, not by
>anthropologists, but by a team of biologists and plastic surgeons at the
>University of Pennsylvania and the Children's Hospital of Philadelphia.
>
>The report provoked strong reactions throughout the hotly contested
>field of human origins with one scientist declaring it "counter to the
>fundamentals of evolution" and another pronouncing it "super."
>
>The Pennsylvania researchers said their estimate of when this mutation
>first occurred — about 2.4 million years ago, in the grasslands of East
>Africa, the cradle of humanity — generally overlaps with the first fossils
>of prehistoric humans featuring rounder skulls, flatter faces, smaller
>teeth and weaker jaws.
>
>And the remarkable genetic mutation persists to this day in every
>person, they said.
Mutation ? 2,4 millions d'années ? Impossible !
Denis
