I am a neuroscientist by training and inclination, not an anthropologist, or archeologist. Nor am I geologist, geochemist or any other geo-ist. However, I am inherently curious and skeptical and enjoy watching the discovery channel reading widely and broadly.
According to published scientific reports, around 13,000 years ago, give or take, an asteroid or comet slammed into the earth over North America, or at least exploded in the atmosphere sufficiently close to land, to cause massive environmental upheaval, leading ultimately to the extinction of the “original” North American human colonists, known as the Clovis People, along with all the mammoths, and giant hairy Hamsterbeasts (You made that one up! Ed.) – known collectively as Megafauna.
I’ve seen this take on more popular status and watched shows of varying quality on the History Channel and the Discovery Channel, replete with special effects and extras in dodgy make-up pointing fingers at the sky and then being swept aside in extraterrestrial pyroclastic flows (You made that up! Ed.). I remember reading, in the august Proceedings of the National Academy of Science (PNAS to us geeks), a report by the aptly named Firestone et al. in 2007 adding more details of this event including analysis of magnetic spherules, or microscopic grains that are only formed in the terrible heat and pressure of an extraterrstrial impact. This added weight to the reports of the cause of the so called, “Younger Dryas” that killed off our early and adventurous Eurasian ancestors.
However, a new article, also in PNAS today now casts doubt over all this research, and comes to close to calling it a lot of dodgy of nonsense (You made that up too! Ed.)
Surovell et al. have returned to the impactor sites and, using the techniques applied in previous papers, have attempted to replicate the earlier findings. Surprisingly they find absolutely no evidence of the Younger Dryas impactor.
In all seven sites, we found no distinct peak in magnetic grains or microspherules uniquely associated with the YD and therefore find no support for an extraterrestrial cause of the YD event and New World Pleistocene extinctions.
Now, as I mentioned, I am ex-bench neuroscientist and can only take at face value what i read in the literature outside my area of expertise. However, I was particularly taken by some the authors’ closing remarks about The Scientific method.
In both the resampled sites and our additional sites, using methods taken from Firestone et al., we failed to reproduce their results…Assuming an ET impact occurred, perhaps the lack of reproducibility indicates that the methods used for recovering the magnetic material are not appropriate for the task at hand…[however] The same methods were used at all sites, and our identifications of the magnetic spherules from Lubbock Lake have been confirmed by…one of the authors of the Firestone et al. article, who was involved in much of the laboratory analysis for that work.
They continue,
Replicability is fundamental to the scientific method and hypothesis testing; results that are not reproducible cannot be considered reliable or supportive of a hypothesis. Marlon et al. have examined cores from lakes and bogs for charcoal indicative of “massive burning” associated with a 12.9-ka impact and found no such evidence. We have been unable to find high concentrations of magnetic particles and spherules, considered key impact indicators, at the 12.9-ka level in seven sites that should exhibit this evidence if the impact hypothesis is credible. In short, we find no support for the extraterrestrial impact hypothesis as proposed by Firestone et al. (1).
BOOYAH Right there…that’s a scientific bitch-slap mate.
Usually when something like this happens there is a rapid response in the Commentary section of a journal, and the original authors are given the opportunity to address the claims against them/their data. I shall be eagerly awaiting any rebuttal from the original groups that claimed a Younger Dryas impact event.
And this certainly raises questions, not only obvious ones of why there should be such differences between research groups data on something so fundamental. But it re-opens questions of what did happen to the Clovis people (and other Paleoindian tribes), and what triggered the Younger Dryas and thus the mass extinction of plasticine Pleistocene megafauna?
