A few weeks ago, I received a very surprising press release from a Quebec archaeologist announcing evidence from the south of France pointing to a 200,000-year-old asteroid explosion. Serge Lebel, a former associate professor at the University of Quebec at Montreal and now an independent researcher, is the principal investigator of a major Neanderthal site, Bau de l’Aubesier, in Provence. He now contends that he has found clear proof at the French rockshelter of a previously unknown extraterrestrial event.
I met Lebel in the early 1990s, when I spent a week at Bau de l’Aubesier in order to interview him and his team for a feature article. Lebel struck me at the time as a cautious researcher: he was very reluctant to speculate in any way, or to go beyond the evidence he had in hand. And since then, he has made some important contributions to science. In 2001, for example, he was the lead author of a major paper in the Proceedings of the National Academy of Science (PNAS) on Middle Paleolithic human remains excavated at Bau de l’Aubesier. The research seemed to be unfolding in a conventional way.
So I was a little taken aback by Lebel’s announcement. We have now exchanged several emails on the subject, and this, in brief, is what I have learned. The evidence for an asteroid explosion comes from H1, a black, continuous 40-cm-thick layer at the site. Lebel has long mulled over the origins of this layer: it seemed far too thick and extensive for hominin hearths or fireplaces. Now he has discovered 10 meteorites (all less than 2 centimeters in diameter), micrometeorites, and metal droplets in situ in the layer. In addition, H1 has produced flint tools coated with a silvery-colored deposit consisting of chromium, iron, aluminum and titanium. The chemistry of this silvery deposit, says Lebel, “is the same as the extraterrestrial material.” And both the limestone deposits in the shelter and artifacts in the black layer show, he says, “the effects of an intense heat (over 4000 degrees Celsius.)”
Lebel contends that this evidence points to the explosion and fragmentation of an asteroid as it entered the earth’s atmosphere, sending a hail of meteorites to the ground. And he proposes, furthermore, that “human populations of this era were witnesses to this event.” When I asked him if any researchers working on other sites dating to around 200,000 years ago had found similar evidence, he noted that Bau de l’Aubesier is currently unique. “The 180,000 to 200,000 years ago period is not well-documented around the world,” he added. “And at the geological time scale, the event is a ‘precise moment’ not always recorded in cave infilling.”
If I had never met Lebel or spent time at the excavations at Bau de l’Aubesier, I would have just deleted his first announcement. Other archaeologists have turned up evidence of another purported extraterrestrial event–the possible explosion of a comet 12,900 years ago that may have triggered global cooling, the extinction of certain species of megafauna and the demise of the Clovis culture. But other research teams now strongly contest these claims. Today, for example, an international research team led by Francois Paquay, a geologist at the University of Hawaii, casts new doubt on the comet strike theory in an online paper in PNAS. Paquay and his colleagues could not find any evidence of extraterrestrial debris in the 12,900-year-old layers they tested in North America.
All this, of course, is good science, as researchers test the comet-strike idea by searching for extraterrestrial evidence in their own data. I’d personally like to see Lebel publish his findings soon in a good journal, so that geochemists and others can take a good look at it there.