Arriving Late, Traveling Far: The Evolution of Human Beings

20.1 The Human Family Tree

The Human Family Tree A common primate ancestor is believed to have given rise to both the chimpanzee and the human family evolutionary lines between 6 and 7 Mya.

The Human Family Tree The structure of the hominin tree is a matter of considerable debate

20.2 Human Evolution in Overview

Human Evolution in Overview Africa Chad Sahelanthropus tchadensis Ethiopia Earliest modern human (Homo sapiens) Kenya Australopithecus fossil discoveries Orrorin tugenensis Paranthropus fossil discoveries Tanzania Australopithecus and Ardipithecus fossil discoveries South Africa Indian Ocean Figure 20.2

Human Evolution in Overview A Hominin Family Tree H. sapiens Present recent H. neanderthalensis H. heidelbergensis H. floresiensis Pleistocene H. mauritanicus 1 H. cepranensis H. erectus H. habilis 2 K. rudolfensis P. robustus Homo ergaster P. boisei Au. garhi Au. africanus Paranthropus aethiopicus 3 Pliocene Au. bahrelghazali Millions of years ago Kenyanthropus platyops Au. afarensis 4 Australopithecus anamensis Ar. ramidus 5 monkeys gorillas chimps orangutans hominins Ardipithecus kadabba 6 Orrorin tugenensis Sahelanthropus tchadensis ancestral primate 7 Figure 20.1

20.4 Snapshots from the Past: Three Hominins

Australopithecus afarensis Bipedalism clearly existed in Australopithecus afarensis, Most famous, Lucy, lived 3.18 mya in what is now Ethiopia. Much smaller brain than modern humans Partly arboreal, or tree-dwelling.

Australopithecus afarensis Smaller brain Longer arms (shorter legs) Grasping feet Figure 20.6

Three Hominims Figure 20.5

Homo ergaster Physical form and mental capacity much closer to ours comes with the evolution of Homo ergaster, Turkana Boy lived 1.6 Mya.

Homo neanderthalensis Neanderthals (Homo neanderthalensis) populated Europe and parts of Asia for about 130,000 years. Went extinct 28,000 years ago in Europe. “Caveman” image comes from the Neanderthals, though, they were more advanced and buried their dead. Neanderthals were a primitive species in comparison with H. sapiens.

20.5 The Appearance of Modern Human Beings

The Appearance of Modern Human Beings Human beings evolved into their modern form in Africa prior to migrating into the wider world. This is known as the “out-of-Africa” hypothesis

The Appearance of Modern Human Beings The initial wave of human migration out of Africa was initiated sometime between 85,000 and 55,000 years ago.

The Appearance of Modern Human Beings The earliest fossils we have of modern human beings outside Africa and its immediate environs date from 46,000 years ago and were found in Australia.

The Appearance of Modern Human Beings Molecular evidence indicates that modern human beings evolved no earlier than 200,000 years ago. The earliest human fossils we have date from 195,000 years ago and were found in Ethiopia.

The Appearance of Modern Human Beings Arrival of Homo sapiens in Europe 40,000 years ago was followed by the extinction of Neanderthals 12,000 years later. Arrival of human beings in Far East, 46,000 years ago, was followed by the extinction of Homo erectus 6,000 years later.

The Appearance of Modern Human Beings Why are we human beings the only living species of hominin? We “replaced” such species as H. erectus and H. neanderthalensis by out-competing Superior weaponry and hunting; better game/food