Archeologists Study Ancient Teeth To Uncover Evolution Of Disease

Enid Burns for — Your Universe Online

Every civilization leaves clues in artifacts that can tell of how a civilization once lived, thrived, and even became extinct. Now scientists are taking a closer look into a few archeological finds to look at how diseases once thrived and evolved. Particularly, scientists are looking at the teeth of ancient skeletons.

A team of scientists led by the University of Adelaide‘s Centre for Ancient DNA (ACAD) published research in the journal Nature Genetics that looks at oral bacteria brought about by dietary shifts as humans became farmers and adopted technology.

Additional researchers on the international team of scientists include the Department of Archeology at the University of Aberdeen and the Wellcome Trust Sanger Institute in Cambridge in the United Kingdom.

“This is the first record of how our evolution over the last 7500 years has impacted bacteria we carry with us, and the important health consequences,” study leader Professor Alan Cooper, ACAD Director said in a statement about the research.

The research looked at DNA preserved in calcified bacteria on teeth of ancient human skeletons. The research shed light on health consequences of the evolving diet and behavior. The research is able to draw a line from the Stone age to modern day.

Ancient genetic records reveal the negative changes in oral bacteria that resulted in the dietary shifts as humans became farmers. The changes continue as food manufacturing in the Industrial Revolution was advanced.

“Oral bacteria in modern man are markedly less diverse than historic populations and this is thought to contribute to chronic oral and other disease in post-industrial lifestyles,” said Professor Cooper.

Researchers extracted DNA from tartar (calcified dental plaque) from 34 prehistoric northern European human skeletons, and traced the changes in nature of oral bacteria from the last hunter-gatherers all the way through the first farmers, the Bronze Age and Medieval times.

“Dental plaque represents the only easily accessible source of preserved human bacteria,” said lead author Dr. Christina Adler, who conducted the research while a Ph.D. student at the University of Adelaide, and is now at the University of Sydney.

“Genetic analysis of plaque can create a powerful new record of dietary impacts, health changes and oral pathogen genomic evolution, deep into the past,” Dr. Adler said.

Research on the project was conducted over the past 17 years. Archeologist and co-Leader Professor Keith Dobney, now at the University of Aberdeen, was part of the research.

“I had shown tarter deposits commonly found on ancient teeth were dense masses of solid calcified bacteria and food, but couldn’t identify the species of bacteria. Ancient DNA was the obvious answer,” Dobney said.

“The composition of oral bacteria changed markedly with the introduction of farming, and again around 150 years ago. With the introduction of processed sugar and flour in the Industrial Revolution, we can see a dramatically decreased diversity in our oral bacteria, allowing domination by caries-causing strains. The modern mouth basically exists in a permanent disease state,” Professor Cooper said.

While the team has been conducting research for the past 17 years, it was not able to sufficiently control background levels of bacterial contamination until 2007 when ACAD’s ultra-clean laboratories and strict decontamination and authentication protocols became available. The research team continues its work, and is expanding its studies to include longer periods of time, more geographies worldwide, and include other species such as Neanderthals.