Walking on two legs has long been considered a milestone in human evolution and one of our most defining characteristics.

Images: N. Spassov, D. Youlatos, M. Böhme, R. Bogdanova, L. Hristova, D. Begun The Graecopithecus femur from Azmaka, Bulgaria, (left ...

Crystals have repeatedly been found at archaeological sites alongside Homo remains. Evidence shows that hominins have been collecting these stones for as long as 780,000 years. Yet, we know that our ...