The unity of the human species has been proclaimed, based on the findings of skulls in Georgia, dated about 1.8 million years ago.
The skull, along with other partial remains previously found at the rural site, offer a glimpse of a population of pre-humans of various sizes living at the same time — something that scientists had not seen before in such an ancient era.
This diversity bolsters one of two competing theories about the way our early ancestors evolved, spreading out more like a tree than a bush, according to a study published Thursday in the journal Science.
When examined with the earlier Georgian finds, the skull “shows that this special immigration out of Africa happened much earlier than we thought, and a much more primitive group did it,” said David Lordkipanidze, director of the Georgia National Museum and the study’s lead author.
Since a species is defined as the capacity of any male member of it to breed with any fertile female member of it, then, by definition, we are one species. To find out – by inference I add – that the odd assortment of trolls, orcs and dwarves (sorry – ugly looking hominids) found in the Georgian village were likely of one species is important for placing the expansion of humans out of Africa at an earlier date than had been supposed.
By contrast to these events of 1.8 million years ago, the spread into Europe by modern humans began about 40,000 years ago, the Neanderthal migrations much earlier , roughly 600,000 to 350,000 years ago. The fact that many Europeans have between 1 and 3% Neanderthal genes in them argues that the Neanderthals, too, were of one species with us moderns.
A note of caution, however: I have been around long enough to know that anthropological interpretation is subject to uncertainty, conjecture, and fashion. Read the article but take it provisionally. Also read more books on the subject. A good place to start is Before the Dawn, recovering the lost history of our ancestors, by Nicholas Wade.