Normally, when you get news about the early humans, somebody has found a large fragment of a skull and announces that [hardly ever s]he has found a new species, related to modern humans, from about a million years ago. Very seldom do you hear anybody announcing they have found five skulls, and even if they are different, they are of the same species. In the last decades the human early history has been fragmented between different early species and the theory of a single line of evolution has fallen out of favour.
That was before five Homo erectus skulls from Georgia were published in The Science. The founders suggest that, since these individuals come from the same period, they must be of the same species. They probably belong to Homo erectus and some of the African Homo habilis skeletons may actually belong to the same species or subspecies presented by the Dmanisi find. This argument allows allowing early humans more variability than normally assumed. However, since the boundary between different species is proven by their inability to mate between each other and produce viable off-spring, this crucial criterion cannot be shown or denied for these new finds. We cannot observe them in the past in the same way we cannot observe Homo sapiens and Homo neanderthalis in potential action. In that discussion arguments have been split between those who think they could mate and they who thought they did not. The amount of the genes we share with the Neanderthals is quite low allegedly.
I have always been fascinated by the early human species and this news story refreshes some memories of reading too much of Lucy during my teenage years. The fascination did not lead to any concrete attempts to study the Paleolithic period, but remained ‘academic’ and an interest. In this newest story it is the early variability of the early Homo that is astonishing. They managed to settle and move into very different landscapes and climates and showed the kind of variation this new Georgian study suggests already 1.8 million years ago. They had to be versatile in order to succeed in the face of the new.