Hot

The last few days have been hot - really hot.  But we've been preparing for that, for a long time.  The thermal hypothesis of human evolution suggests that various aspects of our history, including bidedalism and the loss of fur, could be related to the extremely warm climates that we ultimately hail from.  Of course, for that idea to work we have to assume that our ancestral home was, in fact, hot as Hades.  That was the goal of a study by a group from Johns Hopkins, published recently in PNAS. 


Lead author Benjamin Passey and his group used a geochemical approach to evaluate past temperatures in the Turkana Basin on Kenya, a region that was home to ancestral hominids for much of our early history.  The group applied istopic analysis to carbonate minerals in the soil, looking specifically at ratios of Carbon-13 and Carbon-18.   This ratio provides a clue to the temperatures at the time of mineral formation.  The analysis revealed daytime temperatures over 90 degree Fahrenheit.  Temperatures such as this make the thermal hypothesis a viable idea.