Epoch· The columns of time

Pleistocene

2.6 Ma → 11.7 ka

The Pleistocene, from 2.6 million to 11,700 years ago, is the epoch of the ice ages, two and a half million years of advancing and retreating ice sheets, crossed by at least three distinct human populations.

Epoch of the ice ages, covering two and a half million years of advance and retreat of the ice sheets, and traversed by at least three distinct human populations.

What the evidence shows

At glacial maxima, ice immobilised enough water for sea level to stand 134 metres below the present one, and the main deglaciation, from 16,500 to 8,200 years before present, took more than eight thousand years to restore it. The pace of the cycles is not constant: at the Mid-Pleistocene Transition they slow and deepen, with no accepted explanation. Hominins leave Africa early in the epoch. One million years ago, the use of fire is attested. Homo sapiens appears around 300,000 years and shares the ice ages with Neanderthals and Denisovans, fragments of whose DNA persist in present-day genomes.

Bounds and conventions

Its base was lowered from 1.8 to 2.58 million years in 2009: the epoch therefore gained three quarters of a million years by a vote and not by a discovery. The change in glacial pacing a million years ago remains unexplained. Finally, occasional use of fire and dependence on it are distinct states: the oldest secure traces are a million years old, whereas habitual use is attested in Europe only around 400,000 years.