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Geomagnetic Field Effects on Living Systems

FIGURE 6.7 Timing of the Laschamp excursion and the extinction of Neanderthals (Channell and Vigliotti,

2019). VADM, Virtual Axial Dipole Moment. (Reproduced with permission from Channell and Vigliotti (2019),

Copyright 2019, John Wiley & Sons.)

According to this report, the extinction of Neanderthals is estimated to be about 41–39 ka (Channell

and Vigliotti, 2019). Te GMF intensity at that time was estimated from the mean value of the “Virtual

Axial Dipole Moment (VADM)” originating from a geocentric axial dipole (Korte and Constable,

2005a,b). VADM refects the absolute paleomagnetic feld strength derived from volcanic rocks (Korte

and Constable, 2005a,b). In more detail, VADM is intensity of an imaginary axial (along the Earth’s

rotation axis) geocentric (located in the center of the Earth) dipole that would produce the estimated

archaeo-/palaeointensity at the sampling site (Korte and Constable, 2005a,b). It is calculated from the

archaeo-/palaeointensity of a sample as estimated by measurements in the laboratory and the magnetic

co-latitude of the sampling site (Korte and Constable, 2005a,b). Here, the timing of this extinction is

almost the same as the peak period of the Laschamp excursion (Channell and Vigliotti, 2019).

It is believed that the Laschamp excursion caused an extreme decrease in the GMF intensity, which

destroyed the stratosphere ozone (O3) layer, resulting in a sharp increase in UV-B (280–315 nm) radia­

tion, which made the Neanderthals extinct (Channell and Vigliotti, 2019). By the time the Laschamp

excursion occurred about 41 ka, the Cro-Magnon Man, a modern human Homo sapiens, already existed

and coexisted with the Neanderthals (Channell and Vigliotti, 2019). It is supposed that modern humans

are less susceptible to UV radiation than Neanderthals, and therefore have escaped extinction due to

diferences in the aryl hydrocarbon receptor, a transcription factor involved in the regulation of UV