The genus Homo consists of many species, including of course Homo sapiens. All members of our genus have large brains, small teeth and the ability to make stone tools.
About 2.5 -2.3 million years ago (Ma) the earliest members of our own genus diverged from the Australopithecine lineage. This occurred in Africa, and thus far the oldest known Homo fossils come from the Rift Valley in East Africa.
There are as many as nine known species of Homo, but the systematics and phylogenetics of many Homo species are highly debated. Some paleoanthropologists prefer to lump some of the species listed below together, rather than identify as them distinct species.
- Homo habilis, 2.3-1.6 Ma, East Africa
- Homo rudolfensis, 2.4-1.8 Ma, East Africa (sometimes lumped with H. habilis)
- Homo ergaster, 1.8 Ma-200 thousand years ago (ka), Africa (sometimes lumped with H. erectus)
- Homo erectus, 1.8 Ma-200 ka, Asia
- Homo heidelbergensis, 700-130 ka, Europe
- Homo rhodesiensis, 700-200 ka, Africa (sometimes lumped with H. heidelbergensis)
- Homo neanderthalensis, 350-30 ka, Europe and Western Asia
- Homo floresiensis, 90-13 ka, Southeast Asia
- Homo sapiens, 200ka-present, Africa, Europe, Asia, Americas, Australia
The Genus Homo: Big Brains and Small Teeth
Early Homo differs from Australopithicus mainly in the features of the cranium. Brain size in earlyHomo is relatively larger than Australopithecines. H. habilis has a brain size of 635 cc, compared to 400 cc for Australopithecus afarensis, for example. The face, teeth, and jaw bone of early Homoare smaller. Early Homo lacked many of the adaptations to a specialized diet that Australopithecushad.
Was Homo habilis the First Manufacturer of Stone Tools?
Homo habilis means “man of skill”. When Mary and Louis Leakey discovered the first H. habilisspecimen at Olduvai Gorge, Tanzania in 1962, they believed that this species was responsible for the earliest stone tool industry that they found in the same region – the Oldowan. The Oldowan represents the earliest manufacture of stone tools by using one stone to hammer sharp flakes off the edge of another stone. The sharp edges created by breaking the rock were probably used to cut meat and plant products. Larger tools were also used to break bones to access calorie-rich marrow.
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We now know that many species of hominin were on the East African landscape about 2.5 Ma when the first stone tools appear – Homo habilis, Australopithecus ghari, Australopithecus aethiopicus, and Australopithecus bosei. It remains difficult to confidently designate any of these species as the manufacturer of Oldowan stone tools to the exclusion of all the other contemporaneous species.
Homo ergaster/erectus was the First Hominin to Leave Africa
The two million years following the appearance of Homo habilis was witness to a number of significant behavioural and biological milestones. Homo ergaster first appeared about 1.8 Ma and represents many important biological changes in the human body plan – long legs, short arms, very large brains (~900 cc), and tall stature. Homo ergaster was also the first hominin to leave Africa, inhabiting parts of Western and Southeast Asia, where Homo ergaster developed into a new species – Homo erectus.
The Rise and Fall of Homo neanderthalensis
It was not until 200 ka that the first Homo sapiens appeared in East Africa. By this time, some hominins had also colonized Europe and evolved into Homo neanderthalensis who hunted big game and were adapted to the cold, harsh environment of glacial Europe. There is much debate within paleoanthropology regarding the demise of Neanderthals. Many researchers argue that when modern Homo sapiens migrated from Africa into Europe about 40 ka, they displaced Neanderthal populations, driving their eventual extinction.
The Evolution of the Genus Homo
Today, we are the only living representatives of our genus, but the evolutionary history of Homo is a complex one that involved numerous different species across most of the Old World.
To learn more about the behavioural milestones that characterize human evolution, read Key Events in the Human Evolution Timeline
To learn about how stone tool technology changed since it first appeared 2.5 Ma, read Human Evolution and Technological Change
For more articles in the Early Humans series, click here
Klein, R. G., 1999. The Human Career: Human Biological and Cultural Origins. University of Chicago Press., Chicago
Haviland, W. A. and Crawford, G. W. 2009. Human Evolution and Prehistory. Nelson Education Ltd.
Lehman, S.M. 2010. Introduction to Evolutionary Anthropology. Pearson Education Canada: Toronto.