The earliest hominins, who lived roughly six to seven million years ago, had teeth similar to those of apes today; especially helpful for eating “lots of large, fleshy fruit” abundant in the forest habitats that our early ancestors lived in, says Van Casteren. But as rainforests gave way to more woodlands, open habitats and even savannah-like ecologies, hominins had to contend with “more mechanically challenging foods”, says Van Casteren, such as seeds, nuts, and tubers. So they evolved to favour an increase in molar size, with bigger jaws and faces to house all those teeth, alongside the larger muscles needed to power them.
