An international team of scientists says it's uncovered the earliest evidence of man-made environmental pollution, finding it in an unexpected place - on 400,000-year-old teeth.
Researchers from Tel Aviv University in Israel, working with colleagues from the United Kingdom and Australia, have discovered evidence of possible respiratory irritants -- airborne pollutants -- encapsulated within the dental plaque on ancient teeth found in the Qesem Cave outside of Tel Aviv.
The Qesem site has been the location of a number of major discoveries dating to the later Lower Paleolithic period.
The dental plaque, also known as dental calculus and as much a problem today as it evidently was in the distant past, is direct evidence of the Paleolithic diet and, perhaps even of greater significance, the quality - or lack thereof - of the air humans were breathing in their Qesem Cave home, the researchers say.
Trace amounts of charcoal -- a man-made environmental pollutant -- found in the dental plaque may have come inhaling smoke from fires inside the cave over which meat was roasted on a daily basis, they suggest.
Just as it does today, this earliest suspected inhaled environmental pollutant could have had an injurious effect on the health of the Qesem early humans, says researcher Avi Gopher of TAU's Department of Archaeology and Ancient Near Eastern Civilizations.
At first it was thought it would be difficult to garner much information from the ancient teeth, he says.
"Human teeth of this age have never been studied before for dental calculus, and we had very low expectations because of the age of the plaque," he explains. "However, our international collaborators, using a combination of methods, found many materials entrapped within the calculus. Because the cave was sealed for 200,000 years, everything, including the teeth and its calculus, were preserved exceedingly well."
Analysis of the plaque yielded three major "time capsule" findings, the scientists say: Charcoal originating in indoor cooking fires; evidence of plant-based components in the diet; and fibers possibly used in cleaning teeth.
While other members of the research team, in earlier studies, had conducted similar research on dental calculus from Neanderthal teeth found in Spain, they date to only around 45,000 years ago.
"We are talking far earlier than this," says TAU's Ran Barkai.
"This is the first evidence that the world's first indoor BBQs had health-related consequences," Barkai says. "The people who lived in Qesem not only enjoyed the benefits of fire - roasting their meat indoors - but they also had to find a way of controlling the fire, of living with it."
The finding is one of the first, if not the very first, discovery of man-made pollution in human history, he says, a problem we still deal with today.
"On the one hand, we are dependent on technology, but on the other, we are inhaling its pollutants. Progress has a price - and we find possibly the first evidence of this at Qesem Cave 400,000 years ago."
