The technique people are most likely to have heard of is carbon dating.
It hinges upon the presence of carbon-14, a radioactive isotope of carbon that accumulates in the bodies of animals throughout our lives, and gradually decays after we die.
The calcium-potassium age method is seldom used, however, because of the great abundance of nonradiogenic calcium in minerals or rocks, which masks the presence of radiogenic calcium.
On the other hand, the abundance of argon in the is relatively small because of its escape to the atmosphere during processes associated with volcanism.
As I reported at the time, scientists extracted 1,550 fossil fragments from the cave, which were then assembled into at least 15 individual skeletons—one of the richest hauls of hominid fossils ever uncovered.
But one significant problem clouded the excitement over the discovery: The team doesn’t know how old the fossils are.
And without that age, it’s hard to know how fits into the story of human evolution, or how to interpret its apparent habit of deliberately burying its own kind.
He said that his team and the laboratories they employed took special care to avoid contamination.
That included protecting the samples, avoiding cracked areas in the bones, and meticulous pre-cleaning of the samples with chemicals to remove possible contaminants.