Believe me: there is no Darwinian jungle harsher than the field of studies of human evolution. Those who venture into this field must confront, among other things, the relative lack of material for analysis – fossils of our distant ancestors are relatively rare, and becoming rarer the further back in time we go – fierce competition with other researchers internationally, challenges of interdisciplinarity and even geopolitical uncertainties, which also make access to fossilized material difficult. For all these reasons, it is exciting to see Brazilian scientists carving out more and more space in this field, especially when they are willing to tackle one of the most troubling mysteries in paleoanthropology.
I am referring to the curious case of hominins (members of the human lineage) from Dmanisi, Georgia, which was historically one of the great crossroads between Europe and Asia. The five skulls excavated in the Caucasus country in the 1990s and 2000s, estimated to be 1.8 million years old, were originally classified as members of the species Homo erectus – in theory, the first human species to leave our home in Africa.
However, there is a problem. The diversity of brain sizes and maxillofacial shapes among these five specimens is large—certainly greater than would be expected among members of our own species, for example.
One possible explanation for this discrepancy is so-called sexual dimorphism. In other words, the differences in size and anatomical detail that often appear between one sex and another within the same species (and thanks to them, in several cases, the pathologist is able to distinguish the skeleton of a male person from that of a female person).
However, it is estimated that two different hominin species coexisted at Dmanisi, which would not be impossible, considering other instances of this type in Africa and elsewhere. They even suggested (quite obvious) names for them: H. Georgikos and H. Caucasian. How do you know which hypothesis is correct?
This is where the Brazilian contribution to the discussion comes into play, which has just been published in the journal PLOS One. Signed by Victor Neri, Walter Nieves, and Leticia Vallotta (all of the Institute for Advanced Study at the University of the South Pacific), and Mark Hope, of Ohio State University (the latter author is also Brazilian, despite the name and institution), the work compares the teeth of the mysterious Georgian ancestors with those of dozens of other hominins, something that has not been investigated much before.
The Brazilian group compared the crown area of teeth (the visible part of the tooth, above the root), and the clues they identified were interesting. In short, some individuals from Dmanisi, in fact, fit into the diversity of the genus Homo. But at least one of them is closer to australopithecines, the most primitive hominins, which in theory would never have left Africa.
Or maybe not? Other work by the University of the South Pacific group, carried out in Jordan using stone tools, indicates the first expansion of our lineage before the voyages of humans. Homo erectusWhich seems to match Dmanisi’s data analysis. For change, we will need more excavations and more work to solve the mystery. The only thing that is certain is that the past is still more fascinating and complex than it was before.
Current link: Did you like this text? Subscribers can access seven free accesses from any link per day. Just click on the blue letter F below.