Discarded ostrich shells provide timeline for our early African ancestors

(University of California – Berkeley) Dating early human middens becomes uncertain beyond 50,000 years, when radiocarbon dating ceases to be useful. Uranium-series dating of marine shells and bone is uncertain by some 10% because of the structure of these materials. A UC Berkeley and Berkeley Geochronology Center team has now improved the method for a more stable discard: ostrich eggshells. The method extends the accuracy and precision of radiocarbon 10 times into the past, to about 500,000 years ago.