Your smile is likely one of the first things a person notices about you.

Now, experts have found that the shape of our teeth may have been influenced by Neanderthals.

A study has revealed that interbreeding with the ancient species of human thousands of years ago still has lasting genetic effects on some people today.

And it has led to substantial differences in teeth between ethnicities – especially for Europeans who have inherited the gene.

The team, which included researchers from University College London (UCL), analysed data from 882 volunteers in Colombia of mixed European, Native American and African ancestry, including dental crown measurements derived from 3D scans of dental plaster casts.

They compared these measurements with the participants’ genetic information and identified 18 genome regions that influence the size and shape of different groups of teeth.

One of the genes is believed to be inherited from Neanderthals due to interbreeding with ancient humans.

Carriers of the gene have thinner incisors – the eight teeth at the front of the mouth.

Genetic variants that determine the shape of your teeth include a gene inherited from Neanderthals, report the scientists (file photo of Neanderthal skull)

Pictured, an example of the dental scans researchers used to measure the tooth dimensions, However, they don’t know if this is from a person carrying the Neanderthal gene. The blue teeth show the arrangement of teeth in our lower jaw as it would naturally be. This is called our dental arcade. The white teeth are aligned versions of the same teeth, where they are all aligned along the same directions – width, height, thickness

Interestingly, this genetic variant, which contributes to tooth development, was only found in those of European descent. 

On the whole, those of European descent also had smaller teeth.

Lead author Dr Kaustubh Adhikari said that while this gene makes people have thinner teeth, it does not mean they will be more sensitive or prone to cracking.

‘The “thickness” of the incisors we are talking about is the overall dimension of the incisor from front to back, not the thickness of the enamel layer,’ he said.

‘The variation in overall thickness that we observe, given that these are all healthy people with no dental malformations, is modest.

‘Our study volunteers didn’t have hyper-thin teeth which might’ve been more crack-prone or sensitive.

‘In other words, the slightly thinner teeth that some of these people have, due to the gene we identified, is not a bad thing.

‘So it’s nothing to worry about – it’s all part of normal human variation.’

Neanderthals were an early relative of humans who died out around 40,000 years ago, although their time on this planet did overlap with modern humans (homo sapiens). Pictured, a recreation of a Neanderthal woman

While having a thin layer of enamel on the teeth can influence whiteness, Dr Adhikari said that is not the case in this instance.

‘Tooth sensitivity and whiteness are usually influenced by enamel – the thin but strong layer coating the outside of your teeth’, he said.

‘The genes that influence enamel are different from the genes we have found in our study, which is not a surprise because we didn’t study enamel, we studied only the overall size of the tooth.

‘As far as we understand, the two things are being controlled by somewhat separate biological processes.’

Co-lead author Professor Andrés Ruiz-Linares added: ‘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.’

The lead authors of the study have previously found that genes inherited from Neanderthals may impact the shape of our noses, and also contribute to greater overall pain sensitivity.

Their findings were published in the journal Current Biology.

WHY DID THE NEANDERTHALS DISAPPEAR? 

It was commonly thought that Neanderthals died out because they were unable to compete with modern humans for food and resources.

But a 2014 study by the University of Oxford suggests that both groups co-existed for between 2,600 and 5,400 years and some interbreeding occurred.

Experts believe that Neanderthals ‘may have survived in dwindling pockets of Europe’ for several thousand years before becoming extinct, instead of being immediately replaced by modern humans.

We once lived among Neanderthals but, around 40,000 years ago, they disappeared. Suggested reasons for their demise vary, but experts have indicated interbreeding, climate change and violent clashes with humans may be to blame (stock image)

The study didn’t cover eastern regions such as Uzbekistan and Siberia, where Neanderthals are also known to have lived.

‘So it is still possible Neanderthals lingered later in some areas,’ said anthropologist Professor Chris Stringer.

‘Overall pattern seems clear – the Neanderthals had largely, and perhaps entirely, vanished from their known range by 39,000 years ago.’