A fascinating new article in Science News that posits that "A magnetic field reversal 42,000 years ago may have contributed to mass extinctions." The article also suggests that the sudden appearance of red ochre handprints in caves may have come about due to ochre being used as a protective sun screen to shield against large-scale changes in weather patterns and ultraviolet radiation causes by a reversal of the earth's magnetic poles. Here is the lay article: , and here is the research article: https://science.sciencemag.org/content/371/6531/811.