A new study explains why Neanderthals were so stocky.

There used to be only one kind of human-like being on earth. Over time, these beings evolved into different species, including Homo sapiens (that's us!) and Neanderthals, a species that coexisted with Homo sapiens and died out about 30,000 years ago, only to be resurrected in Geico commercials.

Unlike us, Neanderthals were short and stocky, with wide pelvises and rib cages. "Everybody knows him – everybody has a mental picture of him," says Germany's Neanderthal Museum website. Why did these cavemen look so different than us, in all our relatively tall, lean glory? Scientists have just figured out the answer, and it comes down to .... meat.

Researchers at Israel's Tel Aviv University just announced that Neanderthals may have evolved to be so squat because they started eating more protein than Homo sapiens.

Scientists have long known about the physical differences between us and our Neanderthal cousins. (Photo: Nicolas Primola/Shutterstock)

"During harsh Ice Age winters, carbohydrates were scarce and fat was in limited supply. But large game, the typical prey of the Neanderthal, thrived," said Tel Aviv University PhD candidate Miki Ben-Dor, who co-authored the study. "This situation triggered an evolutionary adaptation to a high-protein diet – an enlarged liver, expanded renal system and their corresponding morphological manifestations. All of these contributed to the Neanderthal evolutionary process."

While Homo sapiens certainly ate some meat, they ate more plants than animals. Neanderthals, who moved out of Africa and into colder climates much earlier than Homo sapiens, needed to start eating bigger game to get their calories. Since processing meat and fat takes a different kind of digestive system, Neanderthals needed extra space in their core to house a bigger liver and other adaptations.

While no one can go back in time to see what happened for sure, there's actually a lot of modern evidence suggesting that high-protein diets result in bigger livers and kidneys.

"Early indigenous Arctic populations who primarily ate meat also displayed enlarged livers and the tendency to drink a lot of water, a sign of increased renal activity," Ben-Dor said.



It looks like we have plants to thank for our slender bods.

