Ancient Oral Health: How Dental Plaque Reveals Hominids’ Diet

Ancient Oral Health: How Dental Plaque Reveals Hominids' DietNewswise is reporting on a 2 million-year-old mishap that befell two early members of the human family tree that is providing the most robust evidence to date of what at least one pair of hominins ate.

A team of researchers including Peter Ungar, Distinguished Professor of anthropology at the University of Arkansas, disclose their findings today in the journal Nature.

Almost 2 million years ago, an elderly female and young male of the species Australopithecus sediba fell into a sinkhole, where their remains were quickly buried in sediment.

In 2010, anthropologist Lee Berger of the Institute for Human Evolution at the University of the Witwatersrand in Johannesburg, South Africa, and his colleagues described the remains of this newly characterized creature.

Now a team of scientists has studied the teeth of these specimens, which proved to have unique properties because of how the hominins died.

“We have a very unusual type of preservation,” Ungar said. “The state of the teeth was pristine.”

Since the two individuals were buried underground and quickly encased in sediment, parts of the teeth were even preserved with a pocket of air surrounding them.

Because of this, the researchers were able to perform dental microwear analyses of the tooth surfaces and high-resolution isotope studies of the tooth enamel on these well-preserved teeth. In addition, because the teeth had not been exposed to the elements since death, they also harbored another thing not discovered before in early hominins – areas of preserved tartar buildup around the edges of the teeth.

In this plaque, the scientists found phytoliths, bodies of silica from plants eaten almost 2 million years ago by these early hominids.

“It’s the first time we’ve been able to look at these three things in one or two specimens,” Ungar said.

Using the isotope analysis, the dental microwear analysis and the phytolith analysis, the researchers closed in on the diet of these two individuals, and what they found differs from other early human ancestors from that period. The microwear on the teeth showed more pits and complexity than most other australopiths before it.

Like the microwear, the isotopes also showed that the animals were consuming mostly parts of trees, shrubs or herbs rather than grasses.

The phytoliths gave an even clearer picture of what the animals were consuming, including bark, leaves, sedges, grasses, fruit and palm.

“We get a sense of an animal that looked like it was taking advantage of forest resources,” Ungar said. This kind of food consumption differs from what had been seen in evidence from other australopiths.

“They come out looking like giraffes in terms of their tooth chemistry. A lot of the other creatures there were not eating such forest resources.”

“These findings tell us a really nice story about these two individuals,” Ungar said. “It’s fascinating that we found something that went into the mouth of these creatures that was still in the mouth of these creatures.”

Ungar conducted the microwear analysis. Amanda Henry of the Max Planck Institute in Leipzig, Germany; Marion Bamford of the University of Witwatersrand; and Lloyd Rossouw of the National Museum Bloemfontein in South Africa conducted the analysis of the phytoliths. Benjamin Passey of Johns Hopkins University; Matt Sponheimer and Paul Sandberg of the University of Colorado at Boulder; and Darryl de Ruiter of Texas A&M conducted the isotope analysis. Lee Berger of the University of Witwatersrand oversaw the project.

See Newswise article: First Plant Material Found on Ancient Hominins’ Teeth

Science Friday: Dental Plaque Bacteria May Trigger Endocarditis

Science Friday: Dental Plaque Bacteria May Trigger EndocarditisIn the future dentists could be the first defence in the prevention of endocarditis.

The UK Society for General Microbiology is reporting that oral bacteria that escape into the bloodstream are able to cause blood clots and trigger life-threatening endocarditis.

Further research could lead to new drugs to tackle infective heart disease, according to the scientists who presented their work at the Society for General Microbiology’s Spring Conference in Dublin this week.

Streptococcus gordonii is a normal inhabitant of the mouth and contributes to plaque that forms on the surface of teeth. If these bacteria enter into the blood stream through bleeding gums they can start to wreak havoc by masquerading as human proteins.

Researchers from the Royal College of Surgeons in Ireland (RCSI) and the University of Bristol have discovered that S. gordonii is able to produce a molecule on its surface that lets it mimic the human protein fibrinogen – a blood-clotting factor.

This activates the platelets, causing them to clump inside blood vessels. These unwanted blood clots encase the bacteria, protecting them from the immune system and from antibiotics that might be used to treat infection. Platelet clumping can lead to growths on the heart valves (endocarditis), or inflammation of blood vessels that can block the blood supply to the heart or brain.

Dr Helen Petersen who is presenting the work said that better understanding of the relationship between bacteria and platelets could ultimately lead to new treatments for infective endocarditis. “In the development of infective endocarditis, a crucial step is the bacteria sticking to the heart valve and then activating platelets to form a clot. We are now looking at the mechanism behind this sequence of events in the hope that we can develop new drugs which are needed to prevent blood clots and also infective endocarditis,” she said.

Infective endocarditis is treated with surgery or by strong antibiotics – which is becoming more difficult with growing antibiotic resistance.

“About 30% of people with infective endocarditis die and most will require surgery for replacement of the infected heart valve with a metal or animal valve,” said Dr Petersen. “Our team has now identified the critical components of the S. gordonii molecule that mimics fibrinogen, so we are getting closer to being able to design new compounds to inhibit it. This would prevent the stimulation of unwanted blood clots,” said Dr Steve Kerrigan from the RCSI.

The team are also looking more widely at other dental plaque bacteria that may have similar effects to S. gordonii. “We are also trying to determine how widespread this phenomenon is by studying other bacteria related to S. gordonii. What our work clearly shows is how important it is to keep your mouth healthy with regular dental care as in brushing and flossing, to keep these bacteria in check,” stressed Dr Petersen.

For more on this finding see: Dental Plaque Bacteria May Trigger Blood Clots

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