How did the Earth come to be occupied by humans? Dr. Afxendiou AP World History - 9 Sachem North High School

Human Origins Most societies have origin myths There are still origin myths today but historians and other social scientists have EVOLUTIONARY EXPLANATIONS for our origins Charles Darwin – suggested in the 1800s that humans and apes had a common ancestor millions of years ago natural selection: ability to survive and reproduce otherwise extinction

Paleoanthropologists Look for fossils in order to reconstruct the story of our origins – ‘Where did we come from?’ ‘Who were our ancestors?’ Fossils are the physical remains of plants and animals Homo habilis – first in our species to have opposable thumbs and to walk upright. Developed first simple tools.

Human Evolution Australopithecines 300,000 30,000 homo neanderthalensis 2.5 million years ago homo habilis 1.5 million years ago homo erectus 3 million years ago Lucy

The human “bush” Popular thought usually imagines a straight-line development from apes to humans, but anthropologists speak of a human “bush,” a variety of interacting and inter-breeding species that finally produced Homo sapiens. Most anthropological models see Ardipithecus ramidus and Australopithecus afarensis as the first steps in the branching-apart of humans from apes about 5 million years ago. One line of further evolution led toward modern Homo sapiens. All the other hominid forms, those in our own line and those in other lines, subsequently became extinct.

The Multiregional Model Homo Erectus Suggests that Homo erectus emigrated from Africa throughout Europe and Asia and developed into Homo sapiens separately in all three regions. Some interbreeding did take place.

The Out of Africa Model Homo Erectus Suggests that Homo erectus did emigrate from Africa, but then died out everywhere else. The evolution to Homo sapiens took place only among those that remained in Africa—who later emigrated to Europe and Asia.

Debate Over African Origins Multiregionalists argue that Homo sapiens evolved after emigration of Homo erectus out of Africa Out-of-Africa proponents believe Homo sapiens evolved in Africa and then migrated to rest of world – this is the dominant idea Both sides agree that racial differences are simply adaptations to climate and are superficial

Global Migration Modern humans spread out from Africa to Europe and Asia between 90,000 and 120,000 years ago Migrations were stimulated by climate change Ice ages lowered water levels and made migration easier

Early Human Migration 150,000—40,000 years ago