Prehistoric Teeth Reveal Why Modern Humans Have Smaller Teeth Than Their Extinct Relatives

Posted: Feb 27 2016, 2:46am CST | by , Updated: Feb 27 2016, 10:38pm CST, in News | Latest Science News


Prehistoric Teeth Reveal Why Modern Humans have Smaller Teeth than Their Extinct Relatives
Skull of Lucy, famous australopiths from Africa, has been used for the study. Credit: David Hocking

New detailed research provides more insight into the human evolution.

Researchers have long wondered why wisdom teeth of modern humans are smaller than their extinct close relatives known as hominins. New research has inched closer to solving this mystery.

Molars including wisdom teeth of ancient hominin species were two to four times larger than those of modern humans and researchers were unable to explain how those large teeth evolved into relatively small ones. Some have attributed it to changes in diet and cooking. But a team of researchers led by Monash University in Australia have found that the evolution of human teeth is much simpler than previously thought.

“Teeth can tell us a lot about the lives of our ancestors and how they evolved over the last seven million years. What makes modern humans different from our fossil relatives? Palaeontologists have worked for decades to interpret these fossils and looked for new ways to extract more information from teeth.” Dr Alistair Evans, lead researcher of the study said in a statement.

In the latest study, researchers provide a simple explanation of human teeth evolution and that is “inhibitory cascade,” a rule that shows how the size of one tooth affects the size of tooth next to it, suggesting that the shrinking of teeth may be explained by basic developmental mechanisms rather than dietary and cultural shifts. 

“Our new study shows that the pattern is a lot simpler than we first thought – human evolution was much more limited.” Evans said.

For the study, anthropologists and developmental biologists from around the world used an extensive database of fossil hominins teeth and modern human teeth collected over several decades. Moreover, they used 3D images to see what is inside the fossil teeth. 

After close analysis, researchers found that hominin teeth fell into two major groups: genus homo which includes both modern humans and extinct human relatives such as Neanderthals and other is australopiths, modern apes that were widespread throughout the Northern and Eastern Africa. Both followed inhibitory cascade rule but with slight difference. 

In australopiths, teeth tend to get bigger towards the end of the mouth while in genus homo if all the teeth were small, the smallest will be towards the back of the mouth.

“What’s really exciting is that we can then use this inhibitory cascade rule to help us predict the size of missing fossil teeth. Sometimes we find only a few teeth in a fossil,” said Evans. “With our new insight, we can reliably estimate how big the missing teeth were.”

Researchers believe this finding not only offers more insight into humans evolutionary past but also provide some clues about how humans may evolve into the future. 

The study was published in journal Nature.

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Hira Bashir covers daily affairs around the world.




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