Dental plaque on Australopithecus sediba teeth. Credit: Amanda Henry

Sorry guys, our early human ancestors didn't have insane, wood-eating jaws

Wood is not good.

JOSH HRALA
9 FEB 2016
 

Back in 2012, researchers made headlines by suggesting that South Africa’s Australopithecus sediba, one of our possible early ancestors, lived on a strange diet of tree bark, fruit, leaves and a bunch of other hard, seemingly inedible objects from the forest floor. Now, an international team of researchers says it's disproved this theory because A. sediba lacked the jaw structure needed for such a hard diet. In fact, eating hard wood would have likely broken their jaws.

"Australopithecus sediba is thought by some researchers to lie near the ancestry of Homo, the group to which our species belongs," said one of the researchers, Justin Ledogar from Australia’s University of New England. "[Y]et we find that A. sediba had an important limitation on its ability to bite powerfully; if it had bitten as hard as possible on its molar teeth using the full force of its chewing muscles, it would have dislocated its jaw."

 

To come to their conclusion, the team created a computer model of an A. sediba skull that was found in South Africa’s Malapa Fossil Site in 2008 - a site labelled as the "Cradle of Humankind". This computer model allowed them to examine the 'chewing mechanics' at work inside the ancient, pre-human’s mouth.

When everything was analysed, the team found that A. sediba didn’t have the proper jaw structure or tooth formation to make a diet of wood and leaves possible. 

Though they are hesitant to fully claim that A. sediba were in fact early human ancestors, it’s a widely held belief that humanity stemmed from them or another pre-human species that was a lot like them. Understanding how these ancient beings ate is vitally important, because researchers believe that dietary restrictions set in motion the evolutionary traits that eventually gave way to humans. 

About 4 million years ago, pre-human species were evolving in a bunch of different directions. The new findings point out that some pre-human species evolved to have bigger, stronger jaws that may have been able to bite through extremely tough things like wood and some nuts.

A. sediba, on the other hand, likely evolved in the other direction and relied on softer foods - a diet that aligns with how we eat today. Sure, we can bite through some tough foods, but there’s no way our teeth can handle chomping through bark that hasn’t been boiled for hours to soften it up. 

As research in this area continues, we will hopefully understand how natural selection and dietary restrictions led to the creation of humankind. After all, understanding where we came from is one of the best ways to know where we’re headed. 

You can read the team’s full article in Nature Communications.  

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