Our ancestors' dining habits may have contributed to Neanderthals' extinction.

cavemen eat mammoth and plants
Credit: Jonathan Blair / Getty Images

Before there were cavemen—what scientists dub anatomically modern humans—there were Neanderthals, a subspecies of archaic humans that went extinct some 40,000 years ago. One theory of their demise boiled down to diet: when cavemen came on the scene, their diets were more diverse, scientists thought, and "survival of the fittest"—or, at least, the most nutritionally complex—prevailed in favor of Homo sapiens.

But new research has uncovered that cavemen's diets weren't as diverse as we once thought; in fact, what they put on their proverbial plate looked a lot like Neanderthals.

In the new study, published in the journal Scientific Reports, scientists from Frankfurt's Senckenberg Research Institute analyzed the diets of cavemen, taking data gleaned from the oldest fossils from the Buran Kaya caves on the Crimean Peninsula in the Ukraine. The team measured the percentage of stable carbon and nitrogen isotopes in those fossils and bones—plus the nitrogen-15 content of individual amino acids. In plainer English, that means the team was able to find out what the cavemen ate based on the compounds in their bones.

What the researchers found was a high concentration of nitrogen-15 content that came not from fish products, as many scientists had previously hypothesized, but from mammoths, a key ingredient in the Neanderthals' diet. So now, scientists are inclined to believe that cavemen weren't more enlightened when it came to food; instead, cavemen and Neanderthals were in direct competition for their dinners.

"According to our results, Neanderthals and the early modern humans were in direct competition in regard to their diet, as well—and it appears the Neanderthals drew the short straw in this contest," the team of scientists wrote in their research.

The cavemen did have one key difference in their diets, however: the scientists also discovered they ate a lot more plants than their Neanderthal predecessors. That difference isn't something this study took a deep dive into, but it could be worth exploring down the road: was a plant-heavy diet the key to avoiding our extinction?