The Parade of Men
Scientists in the past, and many people today still believe, that human evolution was a single-file parade, with one type of hominid following another in form and time, as shown here. Based on 150 years of fossil collection and analysis by paleoanthropologists and other scientists, we now have a more accurate picture of human evolution. It looks like a race-track or a bush, with as many as four or five hominid species living on the planet at the same time. Modern humans are not at the end of a long ladder leading to perfection; we are just the only ones left standing. Will we last longer than the other hominid species? Only time will tell...

Footsteps Through Time shows how genes, the environment, and cultural and technological developments have shaped human bodies and behaviors and will continue to interact to shape the future of human evolution. The Footsteps Story follows sixteen moments in time, called Timestones, and showcases select fossils, but the information is corroborated by thousands of scientists and numerous fossil finds.

Mammals survived and thrived when the dinosaurs became extinct 65 million years ago after a dramatic climatic change, which marked the beginning of the Cenozoic era. Primates evolved from a small, shrew-like, tree-dwelling mammal proto-primate, possibly Purgatorius unio, that shared many features with true primates. The story fast-forwards to 34 million years ago, when Aegyptopithecus zeuxis, an ancestor of Old World monkeys and apes, evolved in the Fayum Depression of Egypt. Old World monkeys (living in Africa and Asia) and New World monkeys (living in Central and South America) separated from a common ancestor between 34 and 25 million years ago. Apes were more common than monkeys 20 million years ago, and were evolving into a wide variety of species. One of these species was Morotopithecus bishopi, a primate with a modern ape-like form.

Hominid evolution begins approximately 4.4 million years ago with Ardipithecus ramidus, the earliest fossils yet found that show evidence of bipedalism. Fossils from a species named Australopithecus afarensis, who lived 3.8 to 2.9 million years ago, provide strong evidence of bipedal walking. Although its brain was small, the position of the foramen magnum, pelvis, knee, and femur showed that A. afarensis walked on two legs. Another species, A. africanus, shared the australopithecine "scene" with A. afarensis. Fossils of A. africanus such as Mrs. Ples and Taung Child have been dated to 3 to 2.5 million years ago and show evidence of both ape-like and human-like features. Australopithecus aethiopicus also lived 2.5 million years ago. Approximately 2.3 to 1.3 million years ago, Australopithecus boisei, a type of robust australopithecine, evolved in Africa. A. boisei had a large sagittal crest on top of its head, large chewing molars, and a broad, flat face. This species and its other australopithecine cousins were once widespread all over East Africa, but eventually became extinct.

Another group of hominids, now designated as the genus Homo, were evolving in Africa at the same time as australopithecines. A type of stone tool technology dated to 2.5 million years ago was first discovered in Olduvai Gorge, Tanzania. This tool technology, called Oldowan, was found in the same layers with Homo habilis/rudolfensis fossils (2.4 to 1.6 million years ago). Homo ergaster lived 1.8 to 1.5 million years ago and had a larger cranial capacity as well as a smaller face and teeth than earlier hominids. H. ergaster probably had the ability to control fire. Homo erectus, a close relative of H. ergaster, was the first hominid to migrate out of Africa into parts of Europe and Asia. A transitional species between H. erectus and H. neanderthalensis (Neandertals) lived in Europe and Asia. This species, Homo heidelbergensis, split off from H. erectus 800,000 to 250,000 years ago.

Homo neanderthalensis survived in the cold, harsh climate of Ice Age Europe from 300,000 to 30,000 years ago. At the same time that Neandertals were living in Europe, Homo sapiens evolve from H. heidelbergensis 120,000 years ago in Africa. These H. sapiens fossils show a high, smooth, rounded skull with a straighter face and smaller teeth. Fully modern Homo sapiens, known in Europe as Cro-Magnon, lived throughout the world by 40,000 to 23,000 years ago. Cro-Magnon is known for cultural achievements such as beautiful cave art, body ornamentation, and other evidence of symbolic communication. Physical features of Homo sapiens living today are not much different from those of Cro-Magnon, but we have had many cultural advances over the last 40,000 years that have significantly changed our daily life and our planet.