Our Ancient Ancestors Loved Eating Grasses, and It Eventually Transformed Their Teeth

[Judi Lynn]

Learn how the hominins’ consumption of grasses led to changes in their teeth around 700,000 years later.

By Sam Walters
Jul 31, 2025 5:00 PM

Millions of years ago, our ancient ancestors transitioned from the forests to the grasslands of Africa, where their need for new food sources led to their consumption of grasses.

But recent research suggests that the hominins learned to love these plants, including their grains and their underground organs, thousands of years before their teeth had transformed to eat them effectively. In fact, it took a long time for the hominins’ tastes and teeth to align, with their molars evolving over time, shrinking and stretching, to make munching through tough grassy plants easier.

Reported in Science, the results reveal that behavioral adaptations have prompted physical adaptations in hominins through the evolutionary process of “behavioral drive.” This means that the hominins were able to adapt to their new environment through the transformation of their diet before the transformation of their teeth — an ability that could have contributed to their success.

“We can definitively say that hominins were quite flexible when it came to behavior,” said Luke Fannin, a study author and a researcher at Dartmouth College, according to a press release. “And this was their advantage.”

Behavioral drive, or the ability of behavioral adaptations to propel physical adaptations, is an important process in evolution. But detecting it can be challenging in fossil species, as their behaviors aren’t fossilized, leaving the interpretation of their behavior dependent on the interpretation of their morphology.

More:
https://www.discovermagazine.com/the-sciences/our-ancient-ancestors-loved-eating-grasses-and-it-eventually-transformed