Homo floresiensis extinct by 50,000 years ago
A new study published in Nature has suggested that Homo floresiensis became extinct much earlier than originally reported. The type specimen LB 1, recovered from Late Pleistocene sediments at Liang Bua, Flores in 2004 was claimed to be 18,000 years old, with other remains and associated stone tools dating from 74,000 to 95,000 years old. The dates were inferred from radiocarbon, thermoluminescence, uranium series and electron spin resonance dates on associated sedimentary material. No direct dates were obtained from the remains themselves for fear of damaging them. However, some authorities were dubious that the ‘hobbits’ could have survived for so long after modern humans reached Southeast Asia.
It has now been discovered that the hominin remains and artefacts were found in a stratigraphic sequence of older sediment forming a pedestal, which have been truncated by one or more phases of erosion and subsequently covered by later sediment. This was not recognised during the original excavations, hence making the accuracy of the inferred dates suspect.
The new dates have been obtained by dating the main stratigraphic units within the pedestal; and this time direct dating was also applied to the skeletal remains of Homo floresiensis. Radiocarbon, thermoluminescence, and uranium series methods were used. The revised dates suggest that the skeletal remains range from 60,000 to 100,000 years old and the associated stone tools range from 50,000 to 190,000 years old.
Parts of Southeast Asia may have been inhabited by Denisovans during this period, and modern humans reached Australia by 50,000 years ago. Whether either came into contact with Homo floresiensis or were connected to its demise is at this stage still unknown.
Sutikna, T. et al., Revised stratigraphy and chronology for Homo floresiensis at Liang Bua in Indonesia. Nature, doi:10.1038/nature17179 (2016).