We have been able to determine the sex of 18 individuals, half of them women, and also their ages. There are no children under 3, but individuals under the age of 13, adolescents between 13 and 17 (the most represented age) and just 3 individuals over 30 entered the Pit. Aspects that we know about their lifestyle include the fact that they were hunter-gatherers, but not from evidence found at this site: the only associated animal remains are from bears, lions, lynxes, wildcats and weasels.

The explanation for the large-scale assemblage of bodies here has been and will continue to be fiercely debated. Sima de los Huesos was obviously not inhabited: there are no tools and no herbivore remains. Several hypotheses have been proposed, one of which was confirmed in 1998 when a hand axe known as Excalibur was discovered. This has led the Atapuerca Research Team to lend its weight to the hypothesis that Sima de los Huesos is a deliberate assemblage of corpses, which means that we possibly have the oldest evidence of symbolic, perhaps funerary, behaviour in human history.

In 2006, the fifteenth skull was unearthed, along with more than 160 human remains. The 2007 dig yielded a new 500,000 year old skull. Skull 16 includes two items from an ear, a parietal and the frontal of a young girl.