It’s certainly a fact worth chewing over.

Humans have small, slender heads and weaker jaws, because of our discovery of soft foods like cheese and dairy, a new study suggests.

Research by The University of California suggests the advent of farming, especially dairy products, had a small but significant effect on the shape of human skulls.

The reason is all in the effort it took to eat farmed food. Humans who live by hunting and foraging wild foods have to put more effort into chewing than those surviving on a softer diet of cheese and cereal mush.

Without the daily work-out of crunching, grinding and gnawing, bones and muscle declined, refining the features of farming communities.

“The effect of farming is mostly visible in the areas of the skull that generate or experience stress during chewing,” said graduate student David Katz, formerly of UC Davis, who is now a postdoctoral researcher at the University of Calgary, Alberta.

“The simplest explanation is that these stresses were reduced because farming diets were generally softer.”