In “Jawbones are ‘shaped by diet’, a study finds” (BBC News , 23 November 2011), Jennifer Carpenter addresses the recent finding that a switch to farming led to shorter and broader jaws; one suggested outcome is an increase in tooth problems.
It would be tempting to conclude that this is evidence for concurrent evolutionary change – where jaw bones have evolve to be shorter and broader multiple, independent times, she told BBC News.
But the sole author of the paper suggested that the changes in human skulls are more likely driven by the decreasing bite forces required to chew the processed foods eaten once humans switch to growing different types of cereals, milking and herding animals about 10,000 years ago.
For one thing, it’s hardly certain that if people switched back to a rougher diet, the process wouldn’t just reverse itself.
“As you are growing up… the amount that you are chewing, and the pressure that your chewing muscles and bone [are] under, will affect the way that the lower jaw is growing,” explained Dr von Cramon-Taubadel.
So it’s not clear that the change is even heritable in humans.