This month marks the beginning of a five-year project in the Soa Basin of central Flores, Indonesia, to locate more specimens of the species Homo floresiensis — our most recent living cousin in the genus Homo. Originally discovered on August 8, 2003 in the Liang Bua limestone cave excavation site, H. floresiensis has captivated the imagination of scientists and laypersons alike.
Recently I had the pleasure of conversing with Michael Morwood — lead Australian researcher behind the discovery of H. floresiensis. He sent me a copy of his book, The Discovery of the Hobbit, which conveys the excitement of the discovery and the media blitz surrounding the new fossil specimens. In the breaks between his extremely busy schedule producing journal publications and on-site excavations, he also answered some of my questions on the implications for human evolution of the fossil find and aspects of H. floresiensis existence, including their level of intelligence and eventual extinction.
Interestingly, H. floresiensis was not the original name given to the species in the first submission for publication. Rather, Homo floresianus was first proposed. However, a referee pointed out the humorous if not crude realization that the moniker of Homo “flowery anus” may be used to refer to the specimen, and thus they wisely went with their second choice. In homage to a superficial resemblance with the hobbits in J.R. Tolkien’s Lord of The Rings — with a type specimen height of approximately 1.06 metres — they are now affectionately referred to as “the Hobbits.”
The height of H. floresiensis is just one of its distinguishing characteristics that make their recent existence — which ended about 12,000 years ago — interesting. The other is the cranial capacity, which is generally thought of as a good measure of intelligence when compared relatively to body size. The cranial capacity of H. floresiensis was determined utilizing the so-called “mustard seed technique.”
By plugging the orifices of the skull and filling it with mustard seeds, the volume of the cranium, in cubic centimetres, can be determined. Through this method, the cranial capacity of the type specimen was found to be 380 cubic centimetres. A revised estimate utilizing three-dimensional imaging produced a virtual cranial capacity estimate of 417 cubic centemetres. For comparison, modern humans (Homo sapiens) have a cranial capacity between 1200 and 1850 cubic centemetres.
The prevailing view of human evolution migration is the “Out of Africa” hypothesis, which focuses on the genus Homo — of which we humans are also a member —originating in Africa around 2.33 million years ago. To date the oldest hominid fossils found outside of Africa — dated at 1.8 million years — were the Dmanisi hominids (named for the part of Georgia they were excavated from), which include Homo erectus/ergaster. Since these hominids had both a larger cranial capacity and were taller than H. floresiensis, it is suspected that H. floresiensis departed Africa before the Dmanisi hominids, between 1.8 to 2.6 millions years ago. This challenges many of the current assumptions regarding the Out of Africa hypothesis, which according to Morwood is “paradigmatic to our understanding of virtually all major hominid evolutionary innovations,”
According to Morwood, as a species, H. floresiensis existed on Flores for upwards of one million years and survived by hunting stegodons — which belonged to the same family as elephants and mammoths — Komodo dragons and giant birds. They made a range of stone artifacts and utilized fire, all of which are indications of intelligence. However, Morwood suspects that their extinction was due to the arrival of modern humans on the island, the presumed culprits in the extinction of another recent surviving member of the genus Homo, Homo neanderthalensis.
With recent publications in the journal Nature and a special issue of the Journal of Human Evolution having been devoted to H. floresiensis within the last year, research on the fossil hominids located in the Indonesian Archipelago shows no signs of slowing down. If these new endeavours are successful, they will bring us closer to developing a fuller understanding of what H. floresiensis means to hominid evolution, and in the process, perhaps a better understanding of ourselves.