DENVER: Igniting a scientific furor, scientists say they may have found the genetic mutation that first separated humans from their apelike ancestors.

The provocative discovery suggests that this genetic twist — toward smaller, weaker jaws — unleashed a cascade of profound biological changes. The smaller jaws would allow

for dramatic brain growth necessary for tool making, language and other hallmarks of human evolution.

When did this genetic split occur? Scientists assume that the rate of genetic change a species undergoes is relatively constant.Critics said the study wrongly assumes that evolution works so neatly. — AP