Humans evolved through a lengthy biological process spanning approximately six million years, originating from apelike ancestors in Africa
. This evolutionary journey involved gradual changes in physical and behavioral traits that distinguish modern humans, Homo sapiens, from other primates. Key milestones in human evolution include:
- Bipedalism: The ability to walk on two legs evolved over 4 million years ago, marking one of the earliest defining human traits
- Brain development: Over time, humans developed larger and more complex brains, with significant encephalization occurring after the emergence of Homo habilis around 2.8 million years ago and continuing through Homo erectus and later species
- Tool use and culture: Early humans began making and using stone tools, and later developed complex symbolic expression, language, art, and diverse cultures, especially within the past 100,000 years
- Migration: Early humans first migrated out of Africa into Asia and Europe between about 2 million and 1 million years ago. Modern humans spread globally much later, reaching Australia around 60,000 years ago and the Americas about 30,000 years ago
Human evolution is not a simple linear progression but rather a complex, branching "family bush" with many species, some of which left no descendants
. Modern humans share a common ancestor with the great apes, such as chimpanzees and gorillas, from about 6 to 8 million years ago
. Genetic evidence supports the "Out of Africa" model, which posits that Homo sapiens evolved in Africa from earlier species like Homo erectus and then migrated worldwide, replacing or interbreeding with other hominin species such as Neanderthals and Denisovans
. This interbreeding contributed small percentages of DNA to present-day non- African populations
. In summary, humans evolved through natural genetic variation and adaptation to environmental changes, leading to distinctive traits like bipedalism, large brains, tool use, and complex culture, with origins deeply rooted in Africa before spreading across the globe
