The first definitive evidence of poisoned arrowheads came from the mid-Holocene, in an Egyptian tomb dated to about 4,400 years ago and in a South African cave dating to about 6,700 years ago. In both cases, the arrows had been tipped with toxic plant compounds in what's considered by the study authors "a hallmark of advanced hunter-gatherer technology." But now, researchers from the University of Stockholm and the University of Johannesburg have detected traces of natural poison on five of 10 arrow tips collected from the Umhlatuzana Rock Shelter in KwaZulu-Natal, South Africa. In the first direct evidence of poison applied to Pleistocene hunting weapons, the discovery backs up the timing of human use of poisoned arrows by orders of magnitude, to about 60,000 years ago.