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Six Million Years of Human Evolution

Human evolution is the lengthy process of change by which people originated from apelike ancestors. Scientific evidence shows that the biological and behavioural traits shared by all people originated from apelike ancestors and evolved over a period of approximately six million years.

 

Early human fossils and archeological remains offer the most important clues about this ancient past. These remains include bones, tools and any other evidence (such as footprints, evidence of hearths, or butchery marks on animal bones) left by earlier people.

 

Usually, the remains were buried and preserved naturally. They are then found either on the surface (exposed by rain, rivers, and wind erosion) or by digging in the ground. By studying fossilized bones, scientists learn about the physical appearance of earlier humans and how it changed. Bone size, shape, and markings left by muscles tell us how those predecessors moved around, held tools, and how the size of their brains changed over a long time.

 

Archeological evidence refers to the things earlier people made and the places where scientists find them. By studying this type of evidence, archeologists can understand how early humans made and used tools and lived in their environments.

 

Humans and Our Evolutionary Relatives

Humans are primates. Physical and genetic similarities show that the modern human species, Homo sapiens, are most closely related to a group of primate species, the apes. Modern humans and other great apes (large apes) of Africa – chimpanzees (including bonobos, or so-called “pygmy chimpanzees”) and gorillas – share a common ancestor that lived between 8 and 6 million years ago.

Humans first evolved in Africa, and much of human evolution occurred on that continent. The fossils of early humans who lived between 6 and 2 million years ago come entirely from Africa. Early humans first migrated out of Africa into Asia probably between 2 million and 1.8 million years ago. They entered Europe somewhat later, by between 1.5 million and 1 million years. Species of modern humans populated many parts of the world much later. For instance, people first came to Australia probably within the past 60,000 years and to the Americas within the past 20,000 years or so.

 

Most scientists currently recognize some 15 to 20 different species of early humans. Scientists do not all agree, however, about how these species are related or which ones simply died out. Many early human species – certainly the majority of them – left no living descendants. Scientists also debate over how to identify and classify particular species of early humans, and about what factors influenced the evolution and extinction of each species.

 

 

 

 

Human Characteristics

One of the earliest defining human traits, bipedalism – the ability to walk on two legs – evolved over 4 million years ago. Other important human characteristics – such as a large and complex brain, the ability to make and use tools, and the capacity for language – developed more recently. Many advanced traits – including complex symbolic expression, art, and elaborate cultural diversity – emerged mainly during the past 100,000 years. The beginnings of agriculture and the rise of the first civilizations occurred at least within the past 12,000 years.