When monkeys in Thailand use stones as hammers and anvils to help them crack open nuts, they often accidentally create sharp flakes of rock that look like the stone cutting tools made by early humans.
Was it a stone tool or just a rock? An archaeologist explains how scientists can tell the difference
Have you ever found yourself in a museum's gallery of human origins, staring at a glass case full of rocks labeled "stone tools," muttering under your breath, "How do they know it's not just any old ...
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