Evolutionary History

What is the evolutionary history of Homo floresiensis and how does this impact upon what we know about our origins as a species?

While scientists have learned much about the evolutionary history of Homo floresiensis since its discovery, there is still a range of questions that remain unanswered. For instance, researchers continue to debate the evolutionary history that led to the Hobbit’s unique blend of skeletal features. If Homo floresiensis was a descendent of Homo erectus, then the modern-like limb proportions of Homo erectus must have evolved in Homo floresiensis to become more like those of earlier Homo and Australopithecus species, which had shorter legs and more robust upper limbs than Homo erectus. This shift may indicate a return to more arboreal behaviours or represent an outcome of island adaptation. An alternative proposition is that these primitive skeletal traits in Homo floresiensis reflect an ancestry in earlier Homo or Australopithecus groups, instead of the later Homo erectus. This second scenario is more radical, as it implies a currently unknown dispersal event of hominins before Homo erectus spread out of Africa. Regardless of the explanation, more research is needed to bring greater clarity to the evolutionary history of Homo floresiensis.

The revised chronology for Homo floresiensis raises questions about the nature of any interaction between Homo floresiensis and modern humans, and whether our species played a role in the eventual disappearance of the Hobbit. In light of recent genetic research that has shown the presence of extinct hominin DNA (from Neanderthals and Denisovans) in some modern human populations, it begs the question of how Homo floresiensis is related genetically to modern humans and other extinct hominins, and if Homo floresiensis may have contributed to the genetic makeup of Homo sapiens through interbreeding. Unfortunately, the tropical environment of Flores does not favour the preservation of ancient DNA. That said, with the rapid development witnessed in recent palaeogenomic research, it is certainly possible that scientists might be able to characterise the genetic sequence of Homo floresiensis in the near future.

At Liang Bua, the transition from the Pleistocene (associated mainly with Homo floresiensis) to the Holocene (associated exclusively with modern humans) is accompanied by a shift in the type of archaeological finds. As we discussed in week 3, a greater proportion of stone artefacts from the Holocene layers are produced on chert. The frequency of burning activities is also higher during the Holocene. Another example is that, while mollusc remains are largely absent in the Pleistocene deposits, the Holocene deposits contain notable accumulations of freshwater, marine and terrestrial mollusc shells. This observation suggests that mollusc collection was not part of the repertoire of Homo floresiensis activities at Liang Bua, whereas modern humans clearly exploited molluscs, possibly for food and as material for making tools and ornaments, such as beads. Taken together, the dissimilarities between the cultural remains of the two hominin groups likely reflect evolutionary differences in aspects of their behaviour and use of resources, such as diet, mobility, technology, and even symbolism and communication. These differences may go some way to explaining the survival of our species and the extinction of the Hobbit.