It is the stuff dentists scrape off teeth every day and now it has allowed a bunch of scientists to take a peek at what was on the menu two million years ago.
The embargo has just broken on the findings of a study that has revealed what two Australopithecus sediba individuals were eating in the days before they died.
They were able to do this through the study of plaque. What they found was that Sediba was eating bark, palm, fruit, shrubs and herbs.
Eating bark was a bit of shocker, no one expected a hominin to have feasted on this. Before the results came in, scientists had suspected that sediba ate a diet similar to other hominin species, perhaps foraging for food on the savanna.
Sediba however was feeding in a closed forested environment, explained Dr Amanda Henry, a palaeobotanist at the Max Planck Institute, in Leipzig Germany.
These were probably riverine forests that lay close to open grassland. It was Henry who examined the calculus or dental plaque found on the teeth of the two fossils.
These two specimens were discovered in 2008 at Malapa, a site about 40 kilometres west of Johannesburg. The discovery has caused a stir, they are the best preserved and complete hominin skeletons so far found.
They were also the first of their species to be found. It is believed that they died shortly after falling into a sinkhole, and were quickly buried by sediment.
“To think that we have direct evidence of what these near humans put in their mouths and chewed, still preserved in their mouths after two million years is pretty remarkable,” said Professor Lee Berger, of the Institute for Human Evolution at the University of Witwatersrand.
The multi disciplinary team of scientists used isotope analysis, dental micro wear analysis and the examination of the dental calculus in their study.
Henry scrapping off the tartar with a dentist’s pick. Under a microscope, she found phytoliths, silica structures that are found in plants.
At Wits university, Associate Professor Marion Bamford, was able to identify the origins of the phytoliths from their shapes and sizes.
The team now plans to examine the teeth of other hominins.
This study appears in the latest addition of Nature.