Did Homo floresiensis have Down Syndrome?

23rd November 2014

Argue, DebbieThree hypotheses have been proposed for the
phylogenetic position of Homo floresiensis. This species comprises a series of hominin bones discovered during excavations in Liang Bua cave, on the island of Flores, Indonesia. The remains are dated from c.18,000 years ago to 94,000 years ago and represent a population of very small hominins, a little over 1m tall, with short legs in relation to arms, large feet, and archaic shoulder and wrist configurations. H. floresiensis was originally hypothesised to be the outcome of dwarfing of H. erectus in response to the ‘Island Rule’ (Brown et al. 2004). Although this was rescinded following analysis of further skeletal material (Morwood et al. 2005), it remains an extant hypothesis supported by a number of researchers (e.g. Kaifu et al. 2011). Within days of Brown et al.’s 2004 publication that named H. floresiensis, another interpretation was promulgated – that the skeletal material represented a modern human with a genetic disorder, Microcephaly (Henneberg and Thorne 2004). This hypothesis did not survive testing, and within a few years two other disorders, Laron Syndrome and Cretinism, were proposed, neither of which survived testing. In August this year, Down Syndrome in a small-bodied Austromelanesian population was hypothesised as an explanation for the partial skeleton, LB1 (Henneberg et al. 2014). I test this hypothesis by comparing the diagnostic skeletal traits of Down syndrome and observe if these are present on LB1 and I examine if Down Syndrome bones display the archaic characters that are evident on LB1 and the other bones that comprises H. floresiensis. I conclude that LB1 represents a separate species and does not represent a modern human with Down Syndrome.

Citation for this poster:

Argue, D. 2014 Did Homo floresiensis have Down Syndrome? Poster Presented at the AAA/ASHA Annual Conference, 1-3 December, Cairns.

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