Eating softer foods likely changed the shape of the human skull in small but functional ways as modern humans around the world began farming rather than foraging food, a new study finds. Previous studies indicated that the human skull changed somewhat as softer foods from agriculture altered the way people chew food but it was unclear just how prevalent the changes were.

An examination of 559 skulls and 534 mandibles from more than two dozen pre-industrial populations found modest changes — a reduction in jaw size and muscles associated with chewing — as humans adopted farming practices. .

Why it happened: As modern humans began farming, two agricultural staples – cereals made from grains and dairy from domesticated animals – became primary sources of food, the researchers said. Eating both meant people had to chew their food less. The largest changes in skull morphology occurred in populations eating dairy, indicating that consuming the softest foods had the greatest impact. The effects were seen in skulls from around the world, indicating the changes likely occurred on a global scale as humans evolved

One interesting side note: The changes attributed to diet are smaller in comparison to other factors that determine skull size (like female versus male, or environmental factors that limit diet in different parts of the world).