Flores Man - Competing Theories about Homo floresiensis

Why the Scientific Community is Still Debating Flores Man

Homo floresiensis (Liang Bua Cave, Indonesia) and a modern human skull
Homo floresiensis (Liang Bua Cave, Indonesia) and a modern human skull. Peter Brown

In October of 2004, the report of human remains recovered from a cave on the island of Flores in Indonesia raised significant scientific hackles across the world. Homo floresiensis, as the research team who found the bones called it, was reported to be a different species of hominid than us, one never seen before. Called Flores man, or, in the popular press, the Hobbit or the Little Lady of Flores, the bones grabbed our attention because they were morphologically different from any other known hominid species.

To date there are at least nine, and perhaps as many as 14 individuals which have been called H. floresiensis, all recovered from Liang Bua cave. Early reports were that there were two occupations of Flores in the cave, one dated about 17,000 years ago and one about 74,000 years ago. That was a significant problem for the general acceptance of Liang Bua cave, in particular with respect to the still-emerging understanding of the human colonization of Australia about 50,000 years ago. In 2016 the cave stratigraphy was completely reinterpreted and all of the individuals now seem to date between 100,000 and 60,000 years old. The morphology is still inconsistent with current theories about human evolution, but the revised dating is more consistent with Australia's colonization. 

    Prevailing Paradigms

    Most scholars presently hold two dominant paradigms about human evolution that are violated by Flores. The first is that the earliest member of the Homo clan to leave Africa were relatives of those people found at Dmanisi (1.77 mya) in the Republic of Georgia and probably H. erectus.

    The earliest Hominids in East Asia are definitely H. erectus, at Sangiran on Java (1.8 mya). The researchers who found H. floresiensis suggest it is descended from a more primitive hominid that must have left Africa long before Dmanisi. The second violated theory is that H. sapiens was the last living hominid species standing on the planet, after the Neanderthals died out, ~30,000 years ago.

    Since 2004, remains from Denisova cave have made it undeniable that there was at least one previously unidentified human species out in the world and their genetics lives on inside us. But, despite over a decade of steady research at Flores, despite a considerable debate between scholars who stridently (and quite heatedly) disagree with one another about the interpretation of the fossils, in my opinion, no one answer resolves all the questions. We're simply going to have to wait to figure out who Flores was.

    So: Who Was Flores? Three Theories

    There are three main theories in the scientific literature about who Flores was. They are, in no particular order at all:

    • Flores arrived on the island as a previously unrecognized small-bodied species, that evolved in Africa during the Late Pliocene or Early Pleistocene, and diffused to Southeast Asia, possibly descended from Homo erectus, Homo habilis or even a late Australopithecine.
    • Flores is the end product of insular dwarfism of Homo erectus or some other Homo, an example of the "island rule" that is known to operate on other species. Essentially, species which are environmentally constrained to live on small islands tend to evolve smaller body sizes. The island effect is not unheard of in animal populations, and a small human population on Palau who died and were buried between 1000-3000 years ago may represent the "island rule" affecting people. Homo erectus arrived on Flores at least 1 million years ago, based on evidence at the sites of Wolo Sege and Mata Menge.
    • Flores represents a diseased, Down syndrome and/or congenital dwarf version of a modern human, such as Laron syndrome or cretinism. The earliest evidence of Homo sapiens in island Southeast Asia is Jerimalai in East Timor, 42,000 years ago. Australia is widely believed to have been first settled by humans between 50,000 and 60,000 years ago (see O'Connor).

      Lingering Issues

      Irrefutable arguments for all of these are difficult to make for four undeniable reasons, all of which impact the different theories to different extents.

      • Liang Bua is the only site where H. flores has been identified, and there's only one skeleton that is complete enough to look at comprehensively, although the length of what there are of older bones is supportive of a continuing small body form through time.
      • The closest and earliest modern human site in the neighborhood arrived at Sulawesi, 800 nautical miles away, 42,000 years ago.
      • The earliest modern human site on Flores dates to the Holocene (ca 11,000 years ago).
      • The bones are poorly preserved and not fossilized and DNA is not likely to be retrievable.

      Need a satisfying resolution? How about from Cruz and colleagues, who agree that the long-standing disagreement among scholars has led both sides to "carefully check their hypotheses, [and] look ... to uncover new evidence". Further, the whole epistemological battle "increase[s] the probability that the taxonomic status of Homo floresiensis will be resolved."

      Sources

      This article is a part of the About.com guide to Flores Man.

      Aiello LC. 2010. Five years of Homo floresiensis. American Journal of Physical Anthropology 142(2):167-179. doi: 10.1002/ajpa.21255

      Argue D, Donlon D, Groves C, and Wright R. 2006. Homo floresiensis: Microcephalic, pygmoid, Australopithecus, or Homo? Journal of Human Evolution 51(4):360-374. doi: 10.1016/j.jhevol.2006.04.013

      Argue D, Morwood MJ, Sutikna T, Jatmiko, and Saptomo EW.

      2009. Homo floresiensis: a cladistic analysis. Journal of Human Evolution 57(5):623-639. doi: 10.1016/j.jhevol.2009.05.002

      Brumm A, Jensen GM, van den Bergh GD, Morwood MJ, Kurniawan I, Aziz F, and Storey M. 2010. Hominins on Flores, Indonesia, by one million years ago. Nature 464(7289):748-752. doi: 10.1038/nature08844

      Cruz HD, and Smedt JD. 2013. The value of epistemic disagreement in scientific practice. The case of Homo floresiensis. Studies in History and Philosophy of Science Part A 44(2):169-177. doi: 10.1016/j.shpsa.2013.02.002

      Dennell RW, Louys J, O'Regan HJ, and Wilkinson DM. 2014. The origins and persistence of Homo floresiensis on Flores: biogeographical and ecological perspectives. Quaternary Science Reviews 96(0):98-107. 10.1016/j.quascirev.2013.06.031

      Eckhardt RB, Henneberg M, Weller AS, and Hsü KJ. 2014. Rare events in earth history include the LB1 human skeleton from Flores, Indonesia, as a developmental singularity, not a unique taxon. Proceedings of the National Academy of Sciences Early Edition. doi: 10.1073/pnas.1407385111

      Henneberg M, Eckhardt RB, Chavanaves S, and Hsü KJ. 2014. Evolved developmental homeostasis disturbed in LB1 from Flores, Indonesia, denotes Down syndrome and not diagnostic traits of the invalid species Homo floresiensis. Proceedings of the National Academy of Sciences Early Edition. 10.1073/pnas.1407382111

      O'Connor S. 2007. New evidence from East Timor contributes to our understanding of earliest modern human colonisation east of the Sunda shelf.

      Antiquity 81(313):523–535.

      Sutikna T, Tocheri MW, Morwood MJ, Saptomo EW, Jatmiko, Awe RD, Wasisto S, Westaway KE, Aubert M, Li B et al. . 2016. Revised stratigraphy and chronology for Homo floresiensis at Liang Bua in Indonesia. Nature advance online publication.

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      Hirst, K. Kris. "Flores Man - Competing Theories about Homo floresiensis." ThoughtCo, Apr. 1, 2016, thoughtco.com/flores-man-competing-theories-170878. Hirst, K. Kris. (2016, April 1). Flores Man - Competing Theories about Homo floresiensis. Retrieved from https://www.thoughtco.com/flores-man-competing-theories-170878 Hirst, K. Kris. "Flores Man - Competing Theories about Homo floresiensis." ThoughtCo. https://www.thoughtco.com/flores-man-competing-theories-170878 (accessed December 18, 2017).