Previous attempts to date Little Foot have yielded highly uncertain results, ranging from 2.2 million years to over 4 million years old. The dating technique used in the new study, called isochron burial dating, calculates the age of a specimen based on when it was last on the surface, exposed to cosmic radiation that produces radioactive isotopes of the elements aluminium and beryllium. When the sediments washed into the cave, the isotopes stopped accumulating, and instead begin to decay at a steady rate. Nine out of eleven samples from rock surrounding the skeleton gave an age of 3.67 million years.
Thursday, December 7, 2017