Archaeological evidence for thinking about possibilities in hominin evolution.

The emergence of the ability to think about future possibilities must have played an influential role in human evolution, driving a range of foresightful behaviours, including preparation, communication and technological innovation. Here we review the archeological evidence for such behavioural indicators of foresight. We find the earliest signs of hominins retaining tools and transporting materials for repeated future use emerging from around 1.8 Ma. From about 0.5 Ma onwards, there are indications of technical and social changes reflecting advances in foresight. And in a third period, starting from around 140 000 years ago, hominins appear to have increasingly relied on material culture to shape the future and to exchange their ideas about possibilities. Visible signs of storytelling, even about entirely fictional scenarios, appear over the last 50 000 years. Although the current evidence suggests that there were distinct transitions in the evolution of our capacity to think about the future, we warn that issues of taphonomy and archaeological sampling are likely to skew our picture of human cognitive evolution. This article is part of the theme issue 'Thinking about possibilities: mechanisms, ontogeny, functions and phylogeny'.