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Ancient tooth decay DNA reveals changing diets
British and Australian researchers have discovered that tartar preserved on the teeth of ancient skeletons can reveal the effects of changes in human diet and health from the Stone Age to the modern day. The ancient genetic record reveals the negative impact that changes to farming and manufactured foods have had on the evolution of oral bacteria.

The scientists from the University of Aberdeen, the Sanger Institute at Cambridge and the University of Adelaide extracted DNA from tartar – calcified dental plaque – from 34 prehistoric northern European human skeletons. They then traced changes in the nature of oral bacteria from the last hunter-gatherers, through the first farmers to later Bronze Age and Medieval times.

The researchers said this was the first record of how human evolution over the past 7,500 years had impacted on mouth bacteria and their important health consequences.

The project co-leader, Professor Keith Dobney, sixth century chair of human palaeoecology at the University of Aberdeen, said the discovery provided “a completely new window on how people lived and died in the past”.

“Knowing the real genetic history of diseases we still suffer from today will help us better understand and even treat them,” Dobney said. “Being able to track them through time has huge implications for understanding the origins and history of human health – making the archaeological record extremely relevant and important to modern-day medics and geneticists.”

The scientists found that oral bacteria in modern humans were markedly less diverse than in historic populations and this was thought to contribute to chronic oral and other disease in post-industrial lifestyles. The development of farming around 10,000 years ago caused a major shift in human diet, resulting in a significant impact on human health.

The same was true of the much more recent move to eating highly processed flour and sugar, both of which have contributed directly to health problems today such as tooth decay, diabetes and heart disease.

The composition of oral bacteria changed markedly with the introduction of farming, and again around 150 years ago. The researchers found that with the introduction of processed sugar and flour during the Industrial Revolution, a dramatically decreased diversity in oral bacteria occurred, allowing domination by caries-causing strains.

“The modern mouth basically exists in a permanently diseased state. Ironically, the introduction of sugar and carbohydrates contributed to the increase in dental plaque that now holds the vital information scientists are studying,” one researcher noted.

“Until now, scientists have had to rely mainly on indirect evidence or historical documents to tell what people ate and what kind of illnesses they suffered from in the past. But now they can directly extract genetic information on diet and health from the tartar on teeth – which is very abundant and well preserved in the archaeological record – giving them a totally new source of unique information stretching back thousands of years.”

The research team is expanding the study through time, and around the world, including other species such as Neanderthals.

Results of the researcher were published in Nature Genetics.
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