During the next million years a process of rapid encephalization occurred, and with the arrival of Homo erectus and Homo ergaster in the fossil record, cranial capacity had doubled to 850 cm (Such an increase in human brain size is equivalent to each generation having 125,000 more neurons than their parents.) It is believed that Homo erectus and Homo ergaster were the first to use fire and complex tools, and were the first of the hominin line to leave Africa, spreading throughout Africa, Asia, and Europe between .

According to the recent African origin of modern humans theory, modern humans evolved in Africa possibly from Homo heidelbergensis, Homo rhodesiensis or Homo antecessor and migrated out of the continent some 50,000 to 100,000 years ago, gradually replacing local populations of Homo erectus, Denisova hominins, Homo floresiensis and Homo neanderthalensis.

Recent DNA evidence suggests that several haplotypes of Neanderthal origin are present among all non-African populations, and Neanderthals and other hominins, such as Denisovans, may have contributed up to 6% of their genome to present-day humans, suggestive of a limited inter-breeding between these species.

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It was chosen originally by Carl Linnaeus in his classification system.

The word "human" is from the Latin humanus, the adjectival form of homo.

The Latin "homo" derives from the Indo-European root *dhghem, or "earth".

Human evolution is the evolutionary process that led to the emergence of anatomically modern humans.

The topic typically focuses on the evolutionary history of the primates—in particular the genus Homo, and the emergence of Homo sapiens as a distinct species of the hominids (or "great apes")—rather than studying the earlier history that led to the primates.

The study of human evolution involves many scientific disciplines, including physical anthropology, primatology, archaeology, paleontology, neurobiology, ethology, linguistics, evolutionary psychology, embryology and genetics.

Within the Hominoidea (apes) superfamily, the Hominidae family diverged from the Hylobatidae (gibbon) family some 15–20 million years ago; African great apes (subfamily Homininae) diverged from orangutans (Ponginae) about The basic adaptation of the hominin line is bipedalism.

The earliest bipedal hominin is considered to be either Sahelanthropus or Orrorin; alternatively, either Sahelanthropus or Orrorin may instead be the last shared ancestor between chimps and humans.

Ardipithecus, a full biped, arose somewhat later, and the early bipeds eventually evolved into the australopithecines, and later into the genus Homo.