| Chapter 2: | Humans |
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According to archeological findings, humans’ very early forebears are thought to include Ardipithecus ramidus, which lived in both terrestrial and arboreal environments 4.4 million years ago (MYA), and Australopithecus afarensis (3.8 to 3.0 MYA), which was entirely terrestrial. Recently, bones from Australopithecus sediba (1.977 MYA) from South Africa were found that seem especially likely to belong to a Homo ancestor (Pickering et al., 2011). This simplified sketch omits some prehominids that may or may not lie in humans’ direct lineage; others will no doubt be identified as more bones are found, making the family tree look more like a bush (see figure 2). Some proto-hominids may have had much different mating systems and lifestyles.
Hominids evolved in Africa, from where at least three waves of species spread out over much of Europe and Asia. First was Homo habilis (literally “handyman”), the first tool-maker, who emerged in Africa around 2.5 million years ago. About 700,000 years went by before the appearance of Homo erectus, a tall, gracefully slender protohuman looking much like modern human beings. Its name in Latin means “upright human,” but we prefer to call it “the Wanderer.” The first great humanoid traveler, H. erectus reached Java around a million years ago and China soon after.
Back in Africa, H. erectus evolved into H. ergaster (some anthropologists consider ergaster merely a later form of erectus, not a full species. H. ergaster is sometimes equated with H. erectus). H. ergaster gave rise to Neanderthals (H. neandertalensis), whose ancestors reached Europe and the Middle East around 350,000 years ago and further evolved there, reaching their final form about 130,000 years ago. H. ergaster was also the African ancestor of modern humans, H. sapiens, who reached Australia via India at least 50,000 years ago, replacing most H. erectus along the way. At least two intermediate species, H. antecessor and H. heidelbergensis, preceded H. sapiens in Europe.