Over the course of 2 million years, Homo, the genus of hominids that includes modern humans and closely related species, has extended its range from East Africa’s Rift Valley to the whole planet.
The following range maps show the ’empires’ of 5 Homo species.
1. Homo habilis: 2.1 million – 1.5 million years ago
H. habilis is the most ancient representative of the human genus Homo and inhabited parts of sub-Saharan Africa from around 2.1 million to 1.5 million years ago.
H. habilis fossils has been found mainly in the Great Rift Valley system of East Africa, however their geographic range may have been somewhat larger.
2. Homo erectus: 2 million – 300,000 years ago
The earliest H. erectus co-existed with H. habilis in East Africa for several hundred thousand years, while a number successfully expanded their geographic range beyond Africa and across the Old World.
Their territorial expansion most likely coincided with cooling global temperatures and lower sea levels. By 1.8 million years ago H. erectus was living in Georgia, at the crossroads of Western Asia and Eastern Europe. By 1.6 million years ago they had spread east across Asia into India, China, and Indonesia. By 1.2 million years ago they had spread west across Europe into Spain.
In terms of longevity and development, H. erectus was the most successful archaic human species. They are thought to be the first hominid to live in small, hunter-gatherer band-societies, hunting in coordinated groups and using complex tools. This, and their ability to control fire, allowed them to adapt to a wide range of new climates, from jungles/rainforest to areas that were cold in winter.
In most of their range, evidence of H. erectus disappears around 300,000 years ago, although they may have hung on in Indonesia for longer.
Despite the extent of their range, their numbers remained very small throughout their 1 million year-plus dominance of the planet. DNA studies suggest that 1 million years ago the total population of early human species was no more than 60,000.
3. Homo heidelbergensis: 600,000 – 350,000 years ago
H. heidelbergensis also migrated out of Africa, through the Near East and into Europe as far north as Britain.
There is evidence in France that H. heidelbergensis was the first to build simple shelters. There is also evidence in Germany that they were the first to use wooden spears to hunt large game animals. Further evidence in northern Spain shows what may have been a ritual disposal of their dead.
The H. heidelbergensis population which migrated to Europe and the population that remained in Africa became isolated during periods of glaciation. The European population diverged to become H. neanderthalensis around 350,000 years ago, while the African population diverged to become H. sapiens around 200,000 years ago.
4. Homo neanderthalensis: 350,000 – 40,000 years ago
The Neanderthal range included most of Europe south of the line of glaciation, roughly along the 50th parallel north. This included England, France and Portugal in the west; northern Germany; Mediterranean countries like Spain and Italy in the south; and territory in Central Europe, including the Carpathians, the Balkans, and parts of the Ukraine and western Russia. It also extended eastwards into Central and Northern Asia up to the Altai Mountains, and into Western Asia up to the Indus River.
Neanderthals are not known to have ever lived south-west of present-day Israel; their fossils have not yet been found in Africa, but there have been finds close to North Africa, both on Gibraltar and in the Levant. Whenever climate change caused warmer temperatures, the Neanderthals shifted to the northern borders of their range, along with other cold-adapted species of mammals – Middle Paleolithic artefacts have been found as far north as the 60th parallel on the Russian plain.
The total Neanderthal population across this range only numbered around 70,000 at its peak.
Neanderthals died out in Europe around 40,000 years ago, after the arrival of H. sapiens. The two human populations shared Europe for as long as 5,000 years and DNA evidence has shown that they interbred. Most non-African modern humans carry 1 to 3% Neanderthal DNA, while a total of around 20% of the Neanderthal genome exists in the modern human population.
5. Homo sapiens: 200,000 years ago – present
H. sapiens is the only surviving species of the genus Homo. Technology has allowed it to adapt to virtually all climates and extend its range to include all of the planet’s continents except Antarctica and most habitable islands in all of the oceans.
The current population of H. sapiens is over 7 billion, with most (61%) living in Asia. The population is expected to peak at around 9 billion by the end of the 21st century. The last point H. sapiens came close to extinction was around 70,000 years ago following the Toba catastrophe in Indonesia. It was one of the Earth’s largest known supervolcanic eruptions and the cause of a possible 10 year global volcanic winter and a 1,000-year-long cooling episode. In its aftermath, the world population of modern humans could have fallen to as a low as 1,000 individuals.
Likely descended from H. heidelbergensis, H. sapiens appeared in East Africa around 200,000 years ago. An initial attempt to extend the modern human range beyond Africa occurred around 125,000 years ago, when a small number reached the Near East; however, evidence suggests they retreated back to Africa as their settlements were replaced by Neanderthals.
Around 100,000 years ago, three main lines of H. sapiens diverged within Africa. One group colonized Southern Africa, one group settled Central and West Africa, while one group remained in East Africa.
It may have been the after effects of the Toba catastrophe that prompted a small group of East Africans, searching for food or escaping adverse conditions, to cross the much lower levels of the Red Sea and in the process going on to populate the rest of the world.
The group may have split in the Near East. The descendants of one subset went east, rapidly settling the coastal areas around the Indian Ocean, continuing on into South East Asia and reaching Australia by around 50,000 years ago – the first Homo species ever to set foot there.
The descendants of the other subset headed north, some migrating into Central Asia, others reaching Europe by around 45,000 years ago.
East Asia was reached by 30,000 years ago, and their descendants migrated into the Americas around 15,000 years ago as the Late Glacial Maximum began.
Within the last century, humans have also explored Antarctica and the ocean depths, although large-scale, permanent colonization of these environments is not yet feasible.
The last frontier of H. sapien’s geographic range is outer space, however human habitation within closed ecological systems in hostile environments is expensive and limited in duration. No more than 13 humans have lived in space at any given time, and between 1969 and 1972 only 2 humans at a time could spend very brief intervals on the Moon.
No other celestial body has yet been visited by humans, though a number of nations and organisations have expressed intentions to send humans to Mars in the 21st century. There has, however, been a continuous human presence in space on board the International Space Station since 31 October 2000.
Images: Hominid Reconstructions by Elisabeth Daynes