Pertaining to the Pleistocene era. (Pertaining to) first epoch of Quaternary period.

From 11 thousand to 2 millions years ago; extensive glaciation of northern hemisphere; time of human evolution; Also called: Pleistocene epoch, Glacial epoch.
First epoch of the Quaternary period of geological time, beginning 1.64 million years ago and ending 10,000 years ago. The polar ice caps were extensive and glaciers were abundant during the ice age of this period, and humans evolved into modern Homo sapiens sapiens about 100,000 years ago.