Something to chew over: how eating cheese shrank our skulls

HUMANS have small, slender heads because of our consumption of soft foods such as cheese and dairy, it has been suggested.

Research by the University of California claims that the advent of farming, especially dairy products, had a small but significant effect on the shape of our skulls.

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

Without the daily workout of crunching, grinding and gnawing, bones and muscle mass declined, refining the features of farming communities, concluded the study, published in the Proceedings of the National Academy of Sciences.

“The effect of farming is mostly visible in the areas of the skull that generate or experience stress in chewing,” said David Katz, a post-doctoral researcher at the University of Calgary.

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

Hunter-gatherers began to rely on eating domesticated plants and animals from around 10,000 years ago, and archaeologists have noted that skulls began to shrink but could never quantify the change or say why it happened. To pick out the changes, researchers studied 1,000 skulls and jaws from pre-industrial groups throughout the world who were either hunter-gatherers or farmers.

They found that in farming communities, a part of one of the major chewing muscles, the temporalis, became smaller and changed position as communities changed their diet. As a result, the upper jaw became shorter and the lower jaw smaller.

“The main differences between forager and farmer skulls are where we would expect to find them, and change in ways we might expect them to, if chewing demands decreased in farming groups,” said Dr Katz.

“Agriculture changed not only human culture and lifeways, but human biology as well.”

The largest changes in skull morphology were observed in groups consuming dairy products, suggesting that the effect of agriculture on skull morphology was greatest in populations consuming the softest food.

“At least in early farmers, milk did not make for bigger, stronger skull bones,” added Dr Katz.

A previous study by the University of Cambridge suggested that over time skeletons have become much lighter, with bone mass around 20 per cent lighter, and more susceptible to breaking, since the invention of agriculture.