Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling

Abstract

A carbon-rich black layer, dating to Ϸ12.9 ka, has been previously identified at Ϸ50 Clovis-age sites across North America and appears contemporaneous with the abrupt onset of Younger Dryas (YD) cooling. The in situ bones of extinct Pleistocene megafauna, along with Clovis tool assemblages, occur below this black layer but not within or above it. Causes for the extinctions, YD cooling, and termination of Clovis culture have long been controversial. In this paper, we provide evidence for an extraterrestrial (ET) impact event at Х12.9 ka, which we hypothesize caused abrupt environmental changes that contributed to YD cooling, major ecological reorganization, broad-scale extinctions, and rapid human behavioral shifts at the end of the Clovis Period. Clovis-age sites in North American are overlain by a thin, discrete layer with varying peak abundances of (i) magnetic grains with iridium, (ii) magnetic microspherules, (iii) charcoal, (iv) soot, (v) carbon spherules, (vi) glass-like carbon containing nanodiamonds, and (vii) fullerenes with ET helium, all of which are evidence for an ET impact and associated biomass burning at Ϸ12.9 ka. This layer also extends throughout at least 15 Carolina Bays, which are unique, elliptical depressions, oriented to the northwest across the Atlantic Coastal Plain. We propose that one or more large, low-density ET objects exploded over northern North America, partially destabilizing the Laurentide Ice Sheet and triggering YD cooling. The shock wave, thermal pulse, and event-related environmental effects (e.g., extensive biomass burning and food limitations) contributed to end-Pleistocene megafaunal extinctions and adaptive shifts among PaleoAmericans in North America.comet ͉ iridium ͉ micrometeorites ͉ nanodiamonds ͉ spherules

The key role of patrilineal inheritance in shaping the genetic variation of Dagestan highlanders

“…The time to the most recent common ancestor of a set of closely related Dagestan Y chromosomes belonging to haplogroup J1 was estimated to be 11 711 years (95% CI: 15 460-8930, using as priors a uniform distribution between germline and evolutionary estimated mutation rates and 25 years as intergeneration time). This is consistent with the events of spatial reexpansion that took place after the last glacial maximum in the northern hemisphere, the latest being caused by the end of the Younger Dryas cooling (12 900-11 600 ybp 30 ). Moreover, this estimate is in agreement with the archeological record which indicates that some of these ethnic groups have lived in the Dagestan mountains for over 10 000 years.…”

“…Genomic DNA was extracted from whole blood using QIAamp DNA Blood Mini kit (Qiagen, Hilden, Germany), and genotyped for 20 Y-STR loci (DYS19, DYS388, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS385 a/b, DYS437, DYS438, DYS439, DYS448, DYS456, DYS458, GATAC4, GATAH4 and YCAII a/b) and 30 19,20 Seventeen Y-STRs were typed using the Amp cFSTR Y-filer kit (Applied Biosystems, Foster City, CA, USA). The length of PCR products was estimated on the ABI-PRISM 310 Genetic Analyzer using the Genotyper version 3.7 analysis software (Applied Biosystems) and the Y-filer reference ladders.…”

Charcoal in soils of the Allerød-Younger Dryas transition were the result of natural fires and not necessarily the effect of an extra-terrestrial impact

“…Dead wood provided an abundant source of fuel for intense, large-scale fires seen in many records as a concentration of charcoal particles in so-called 'Usselosoils' dated to ca 10,950 14 C BP. A similar trend in increased charcoal indicating increased burning is seen at many sites across North America at this time and it has been suggested by Firestone et al (2007) that this was caused by an explosion of extra-terrestrial material over northern North America, causing the Younger Dryas climate cooling and Megafaunal extinction. We argue that there is no need to invoke an extraterrestrial cause to explain the charcoal in the fossilized soils.…”

“…Haynes (2008) interpreted 'black mats' of mollic paleosols, aquolla, diatomites or algae radiocarbon dated to the Allerød-Younger Dryas transition as 'stratigraphic manifestations' of the cooler Younger Dryas climate which resulted from a rise in local water tables caused by more effective recharge. He also questioned the evidence presented by Firestone et al (2007) for an extraterrestrial impact, noting that the microspherules and micrometeorites they cite are components of cosmic dust that constantly fall to earth making an 'impact' difficult to distinguish on this basis alone. Marlon et al (in press) linked heightened fire activity to abrupt climate changes in the past.…”

Mammoth Extinction and Radiation Dose: A Comment

“…Another mystery still standing is the mass extinction of megafauna, including its icon the woolly mammoth (Mammuthus primigenius). For this, in particular, sometimes extraordinary theories have been suggested, the last one being the impact of a meteor or comet (Firestone et al 2007). This theory now seems negated (Pinter et al 2011), only to be replaced by the next spectacular one, the SPE hypothesis.…”