Changes in African climate may have affected crucial points in human evolution, suggests geologist Peter B. deMenocal in his article, "Climate Shocks," in the September 2014 issue of Scientific American. In this video, he and other researchers examine the evidence: Human ancestral species emergence and extinction, the rise and fall of certain plants, inventions of stone tools, cycles of wet and dry environments, marks on fossil teeth, the human trait of adaptability, and many other aspects. The video was made at a conference at the Lamont-Doherty Earth Observatory in 2012.