Human evolution: stages and driving forces

Human evolution is studied from fossil bones, tools, DNA analysis and dating methods. The ancestors of humans and chimpanzees split about 6–7 million years ago; the 25-million-year date in older textbooks is outdated – it is closer to the time when the ape group arose. The oldest fossils that walked on two legs lived about 7–4 million years ago (Sahelanthropus, Ardipithecus). Australopithecines (about 4–2 million years ago, Africa; the famous “Lucy” is about 3.2 million years old) walked on two legs, had a brain of about 400–550 cm³ and were 1–1.5 m tall. Early Homo – the “handy man” Homo habilis (about 2.4–1.4 million years ago): brain about 600–700 cm³, made simple stone tools. Homo erectus – “upright man” (from about 1.9 million to 100 thousand years ago, Africa, then Asia and Europe): brain 800–1200 cm³, made more complex tools and used fire; the Java finds (Dubois, 1891) and the finds near Beijing belong to this species. Neanderthals (about 400–40 thousand years ago, Europe and western Asia, including the Teshiktash cave in Uzbekistan): brain about 1300–1600 cm³, adapted to cold climate, shorter and strongly built, made tools, used fire and buried their dead. Homo sapiens appeared in Africa about 300 thousand years ago; about 70–50 thousand years ago groups left Africa and spread across the world. The first modern humans in Europe were Cro-Magnons (about 45–40 thousand years ago): brain about 1350–1500 cm³, painted cave walls, made complex tools. Ancient DNA showed that Homo sapiens met and interbred with Neanderthals and Denisovans: about 1–2 per cent of the genome of present-day people outside Africa comes from Neanderthals. About 12 thousand years ago farming and herding began. Evolution is not a straight “ladder”: many species lived at the same time, and the pattern is a branching bush.