The Laschamp-Mono lake geomagnetic events and the extinction of Neanderthal: a causal link or a coincidence?

Abstract

The causes of Neanderthal extinction and the transition with the modern man in Europe and Near East remain largely uncertain. The two main factors currently proposed are the arrival of a modern human competitor and/or the aptitude of the Neanderthals to survive rapidly changing climatic conditions. None of these hypotheses is fully satisfactory because the Neanderthals experienced other large climatic changes and the duration of overlap of the two populations remains largely unknown and even uncertain. No special attention has been given to the geomagnetic excursions of Laschamp and Mono Lake which are synchroneous with the extinction and were the most dramatic events encountered by the Neanderthals over the past 250 thousand years of their existence. During this period the geomagnetic field strength was considerably reduced and the shielding efficiency of the magnetosphere lowered, leaving energetic particles reach latitudes as low as 30. The enhanced flux of high-energy protons (linked to solar activity) into the atmosphere yielded significant ozone depletion down to latitudes of 40 e45. A direct consequence was an increase of the UV-B radiations at the surface which might have reached at least 15e20% in Europe with significant impacts on health of human populations. We suggest that these conditions, added to some other factors, contributed to the demise of Neanderthal population.

The Role of Geomagnetic Field Intensity in Late Quaternary Evolution of Humans and Large Mammals

“…Valet and Valladas () proposed that low magnetic field strength in the Laschamp/Mono Lake excursion interval (40‐33 ka) was an important factor in Neanderthal demise. Why AMHs were not similarly affected has remained an open question considering that the two populations shared habitats for 2,600‐5,400 years (Higham et al, ) or >5 kyr (Lowe et al, ).…”

Assessing the photoprotective effects of red ochre on human skin by in vitro laboratory experiments

“…8,9 It has furthermore been proposed that excessive UVR may have had far-reaching effects on mammalian evolutionary processes. UVR has been implicated in several extinction events, including the disappearance of megafauna during the late Pleistocene 10,11 and the extinction of a number of hominin species 12,13 . These hypotheses are difficult to test because of the uncertainties concerning the dating of extinction events and in calculating the impact of UVR changes at different latitudes and among different populations.…”

Impact of geomagnetic excursions on atmospheric chemistry and dynamics

“…A possible link to the Laschamp event has been suggested (Zech et al, 2011), which has its reasoning in the fact that GCRs have a significant influence on the upper tropospheric and stratospheric chemistry through ionization and the production of NO x and HO x , which can lead to catalytic destruction of stratospheric ozone and production of tropospheric ozone (Calisto et al, 2011). A massive ozone hole during the Laschamp event has in fact recently been suggested as potential factor favouring the extinction of the Neanderthal (Valet and Valladas, 2010). Moreover, the ozone changes affect atmospheric heating rates, which in turn can result in altered temperature gradients and changing wind patterns.…”