Human Origins—Explorations and Discussions in Anthropology, Biology, Archaeology, and Geology discussion

As many of you are aware, since the latter half of the 1990s it has been thought, based upon electron spin resonance Uranium series dating techniques, that the Ngangdon and Sambungmacan Homo erectus fossils found on Java in Indonesia ranged in date from about 28,000 to perhaps as old as 50,000 years ago (Swisher, et al., 1996). This 1996 study implied that it was possible that anatomically modern humans, i.e., Homo sapiens, may have overlapped in time and space with the earlier Homo erectus residents as they colonized southeast Asia between 60,000 and 50,000 years ago.

A recent article entitled, The Age of the 20 Meter Solo River Terrace, Java, Indonesia and the Survival of Homo erectus in Asia, published in the on-line journal Public Library of Science (PLoS ONE, Volume 6, Issue 6, e21562, June 2011), by Etty Indriati, et al., that those initial dates determined in 1996 may be in error. This new evaluation performed by a team that included several of the authors of the 1996 study utilized Potassium/Argon (i.e., 40Ar/39Ar) and new ESR/U-series age estimates. The new dates that have been determined for the "20 meter Solo River Terrace", where the erectus fossils were found, exhibit a range of dates from about 550,000 years ago (K/Ar) to as recent as 143,000 years ago (ESR/U-series). If these new dates hold up, they indicate that while they are relatively recent for Homo erectus (especially the younger date of 143 Ka), that this population of hominins probably were not contemporaneous with later hominin populations, e.g., Neandertals or anatomically modern humans.

Here is a link to the on-line edition of the paper if you are interested in reading it. It can be downloaded and saved as an Adobe PDF document.

http://www.plosone.org/article/info%3...

Truly fascinating stuff!