Richest human fossil site

Open sites in countries like Ethiopia and cave sites in places like South Africa have produced many thousands of human and pre-human fossils, but the highest known concentration of early human skeletons is from the Sima de los Huesos ("Pit of Bones") chamber within a cave system in the Atapuerca Hills, near Burgos in Spain. From 1975 onwards, about 7,000 human bones and teeth have been excavated, representing approximately 28 male, female and child skeletons. The accumulation dates from about 430,000 years ago, and recent research indicates that at least some of the individuals suffered head injuries around the time of their death.

The remains show resemblances to much later Neanderthal fossils, and in 2016 ancient DNA was recovered from one of the leg bones, making it currently the oldest human DNA ever recovered. This DNA also shows affinities to that of Neanderthals, suggesting that the Sima fossils represent very early members of the Neanderthal lineage.

The Sima chamber also contained remains of other species, especially cave bears, but only one artefact (a stone handaxe nicknamed "Excalibur") has been discovered so far.