While many people worry about the photogenic layout of their teeth, chances are most don’t think about individual tooth shape. Well, you should—because it might be partially determined by your Neanderthal ancestry.
An international team of researchers co-led by Kaustubh Adhikari of University College London (UCL) have discovered tooth differences among ethnicities, including an apparent feature determined by a gene inherited from Neanderthals. Their research, published on December 12 in Current Biology, could one day aid in diagnosing and treating genetic dental conditions.
The researchers, including experts from Fudan University in China, used 3D scans of dental plaster casts to analyze tooth measurements of 882 volunteers of European, Native American, and African descent. They then compared these dimensions with the volunteers’ genetic data and pinpointed 18 genome regions involved in the size and shape of various teeth. Notably, 17 of these regions were identified for the first time as being connected to tooth dimensions.
“Teeth can tell us a great deal about human evolution, as well-preserved ancient teeth are particularly important to archaeologists, shedding light on milestones such as when we transitioned to cooked food and human tooth sizes began to shrink. But little is known about the genetic basis of variation within the modern human population on tooth size and shape, partly due to challenges in measuring teeth,” Adhikari said in a UCL statement. “We have now identified numerous genes that impact the development of our teeth, some of which are responsible for differences between ethnic groups.”
Interestingly, scientists suggest that one of the identified genes originates in Neanderthals, with whom ancient humans interbred during our relatively brief prehistoric coexistence. The genetic variant, found only in volunteers of European ancestry, was associated with thinner incisors (measured front-to-back). Researchers also noted that individuals with this variant tended to have smaller teeth overall. Additionally, the team found that the gene EDAR, previously linked to incisor shape in East Asian people, also affects the width of all teeth.
However, “our findings did not shed light on whether the genes that identify tooth shape were selected in evolution due to particular advantages to dental health, so it’s possible that the genes may have been selected due to the influences they have in other areas, with tooth shape differences resulting as a side effect,” Andrés Ruiz-Linares of UCL and Aix-Marseille University, who co-led the study, explained. Simply put, the researchers aren’t sure why the genes developed to impact tooth shape in this way.
“Some of the genes that contribute to the normal variation of tooth dimensions among healthy people can also contribute to pathogenic variation, such as teeth failing to grow in or other dental health conditions,” said Qing Li of Fudan University, who co-led the study. Pathogenic variations are genetic differences that increase an individual’s chances of developing a particular disease or genetic disorder. In other words, the genes that determine tooth measurements might also determine health issues.
Consequently, “we hope that our findings could be useful medically, if people with particular dental problems could undergo genetic tests to help in diagnosis, or if some dental anomalies could be treated one day with gene therapies,” Li added.
It remains to be seen how this research might lead to practical medical applications. In the meantime, the Neanderthal teeth join a host of other features we may have inherited from our long-lost relatives, including pain tolerance and nose shapes.
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