The Time of the Pleistocene
The geological time scale
The geological time scale is a system that divides Earth’s history into standardized intervals based on rock records and fossil content, using both relative and absolute dating methods to establish the age of geological events.
What was in the Pleistocene?
The Pleistocene Epoch was the earlier of the two epochs that constitute the Quaternary Period of Earth’s history, which we are currently in. The Pleistocene began between 2,588,000 and 1,800,000 years ago and ended 11,700 years ago. It is preceded by the Pliocene Epoch of the Neogene Period and is followed by the current Holocene Epoch. The Pleistocene Epoch is best known as a time during which extensive ice sheets and other glaciers repeatedly formed on landmasses and is informally referred to as the “Great Ice Age.”
Flora and Fauna
The plants and animals of the Pleistocene are, in many respects, similar to those living today, but there are important differences. Moreover, the spatial distribution of various Pleistocene faunal and floral types differed markedly from what it is today. Changes in climate and environment led to large-scale migrations of plants and animals, evolutionary adaptations, and, in some cases, extinction. Of particular importance is the evolution of the genus Homo during the Pleistocene and the extinction of large mammals at the end of the epoch.
Mammalian evolution included the development of large forms, many of which became adapted to Arctic conditions. Among these were the woolly mammoth, woolly rhinoceros, musk ox, moose, reindeer, and others that inhabited the cold periglacial areas. Large mammals that inhabited the more temperate zones included the elephant, mastodon, bison, hippopotamus, wild hog, deer, giant beaver, horse, and ground sloth.
In the temperate zones of central Europe and the United States, where deciduous forests, mostly made up of leafy trees, exist today, vegetation was open and most closely resembled the northern tundra, with grasses, herbs, and fewer trees during glacial intervals. Farther south, a broad region of boreal forests, mostly needle-bearing, with varying proportions of spruce, pine, or a combination of both, extended almost to the Mediterranean in Europe and to northern Louisiana in North America.
Early Hominins
The most significant biological development of the Pleistocene was the appearance and evolution of the genus Homo, which is our genus. The oldest species, Homo habilis, probably evolved from an Australopithecus ancestor in the late Pliocene. The species was present in Africa by 2 million years ago and is known from sites as young as 1.5 million years old. Another extinct species, Homo erectus, evolved in Africa, possibly from Homo habilis, and is known from sites dating to about 1.6 million years ago. The species Homo sapiens, to which all modern humans, including you, belong, evolved in the later part of the Middle Pleistocene, and early forms of the species are known from about 400,000 years ago.