[HN Gopher] A global environmental crisis 42,000 years ago
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       A global environmental crisis 42,000 years ago
        
       Author : divbzero
       Score  : 18 points
       Date   : 2021-02-20 18:00 UTC (5 hours ago)
        
 (HTM) web link (science.sciencemag.org)
 (TXT) w3m dump (science.sciencemag.org)
        
       | DiabloD3 wrote:
       | https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/201...
       | Here's a good paper from 2019 that covers this in depth.
       | 
       | "The past strength of Earth's dipole field provides a proxy for
       | UVR flux because of its role in maintaining stratospheric ozone."
       | [...] "The demise of Neanderthals at ~41 ka can now be closely
       | tied to the intensity minimum associated with the Laschamp
       | magnetic excursion, and the survival of anatomically modern
       | humans can be attributed to differences in the aryl hydrocarbon
       | receptor that has a key role in the evolutionary response to UVR
       | flux."
        
         | trhway wrote:
         | While the rest of the body can be protected with bodily hair,
         | animal pelts, grasses, tree leaves, dirt (or something like
         | ochre mentioned in the article), etc. the eyes is the only body
         | part that couldn't be protected from UV back then. When
         | compared to Cro-Magnon, Neanderthals had bigger (and most
         | probably light colored) eyes adapted to the lower light of
         | their more Northern areas. So quick rise in UV (especially if
         | it was not accompanied by the similar scale rise in the total
         | amount of visible light to trigger eyes f-stop equivalent)
         | would have made for noticeable chronic damage to retina and
         | other parts of the eye (googling UV eye damage brings a lot of
         | possibilities), etc. which would be one more factor against
         | them in competition with the Cro-Magnon whose eyes had evolved
         | in the higher UV environment of Africa.
        
       | Supersaiyan_IV wrote:
       | https://phys.org/news/2021-02-ancient-relic-earth-history-ye...
       | "Ancient relic points to a turning point in Earth's history
       | 42,000 years ago"
       | 
       | Just because this article's title is less sensationalistic,
       | doesn't make it any less interesting.
        
       | aritmo wrote:
       | Sadly the full text is not freely available. ScienceMag demands
       | $15.
       | 
       | Is Sci-Hub down? Some of the presumably mirrors redirect to
       | ScienceMag instead.
        
       | godmode2019 wrote:
       | I posted this yesterday
       | 
       | [Ancient kauri shows magnetic pole shift 42,000 years ago](
       | https://www.tvnz.co.nz/one-news/new-zealand/ancient-kauri-re...)
        
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       (page generated 2021-02-20 23:02 UTC)