Did consuming meat actually make us human?

Twenty-four years in the past, Briana Pobiner reached into the north Kenyan soil and put her palms on bones that had final been touched 1.5 million years in the past. Pobiner, a paleoanthropologist, was digging up historical animal bones and trying to find cuts and dents, indicators that that they had been butchered by our early ancestors attempting to get on the fatty, calorie-rich bone marrow hidden inside. “You’re reaching by means of a window in time,” says Pobiner, who’s now on the Smithsonian Establishment in Washington, DC. “The creature who butchered this animal is just not fairly such as you, however you’re uncovering this direct proof of habits. It’s actually thrilling.”

That second sparked Pobiner’s lasting curiosity in how the diets of our ancestors formed their evolution and finally the emergence of our personal species, Homo sapiens. Meat, particularly, appears to have performed an important function. Our extra distant ancestors largely ate crops and had brief legs and small brains comparable in measurement to a chimpanzee’s. However round 2 million years in the past, a brand new species emerged with decidedly humanlike options. Homo erectus had a bigger mind, smaller intestine, and limbs proportioned equally to these of recent people. And fossils from across the identical time, like these excavated by Pobiner in Kenya, present that somebody was butchering animals to separate lean meat from the bone and dig out the marrow. For many years, paleontologists have theorized that the evolution of humanlike options and meat consuming are strongly related.

“The reason has been that meat-eating allowed this: we received much more diet, and these concentrated sources facilitated these adjustments,” Pobiner says. Giant brains are phenomenal power hogs—even at relaxation, a human mind consumes about 20 % of the physique’s power. However a swap to a weight loss program filled with calorie-rich meat meant an extra of power that could possibly be directed to supporting bigger, extra advanced brains. And if prehumans hunted their meals, that will clarify a shift towards longer limbs that had been extra environment friendly for stalking prey over nice distances. Meat made us human, the standard knowledge stated. And Pobiner agreed.

However in April 2020, Pobiner received a name that made her rethink that speculation. The decision was from Andrew Barr, a paleontologist at George Washington College in Washington, DC, who wasn’t completely satisfied concerning the hyperlink between Homo erectus and meat-eating. He needed to make use of the fossil report to verify whether or not there actually was proof that human ancestors had been consuming extra meat across the time Homo erectus advanced, or whether or not it merely appeared that means as a result of we hadn’t been trying laborious sufficient. Pobiner thought this seemed like an intriguing challenge: “I really like the thought of questioning typical knowledge, even when it’s typical knowledge that I purchase into.”

The researchers had been unable to journey to Kenya for fieldwork due to the pandemic, so as a substitute they analyzed information from 9 main analysis areas in Jap Africa that cowl hundreds of thousands of years of human evolution. They used completely different metrics to evaluate how well-researched every time interval was, and what number of bones with butchery marks had been present in every web site. In a new paper within the journal Proceedings of the Nationwide Academy of Sciences (PNAS), Barr and Pobiner now argue that the hyperlink between meat-eating and human evolution may be much less sure than beforehand thought. The obvious enhance in butchered bones after the looks of Homo erectus, they conclude, is definitely a sampling bias. Extra paleontologists went in search of bones at dig websites from this period—and consequently, they discovered extra of them.

This doesn’t rule out a hyperlink between meat-eating and evolutionary change, but it surely does recommend that the story may be a bit extra sophisticated. “If we wish to say how widespread a habits was, then we want some method to management for the truth that at some closing dates and at some locations we’ve appeared more durable for that habits than now we have at different factors,” says Barr. As a result of websites with well-preserved animal bones are comparatively uncommon, paleontologists usually pattern them again and again. However Barr and Pobiner’s research discovered that different websites that date from between 1.9 and a pair of.6 million years in the past—the period throughout which Homo erectus advanced—have been comparatively under-studied. “We’re drawn to locations that protect fossils as a result of they’re the uncooked materials of our science. So we hold going again to those identical locations,” Barr says.