16 April 2010

Young Homo Erectus Find Date Probably Wrong

[A] team that first announced in 1996 that sediment at two H[omo] erectus sites on Java dates to between 50,000 and 30,000 years ago. . . based on analyses of radioactive elements in fossil-bearing sediment, suggest that H. erectus survived well into the era dominated by modern humans. . . But a new analysis [by the same team], based on measurements of radioactive argon’s decay in volcanic rock above and below the fossils, puts H. erectus’ age on Java at roughly 550,000 years. It’s not clear why these estimates differ so dramatically and which one is more accurate. . . A new analysis of sediment on Java suggests that animal fossils on the island date to between 200,000 and 150,000 years ago, providing a[nother] possible framework for when H. erectus lived there[.]

From here.

An earlier Java man fossil date would largely rule out the co-existence of pre-modern human and modern human hominins outside Europe and the Near East where Neanderthals and modern humans co-existed for about eighteen thousand years, outside the island of Flores, where a species of hominin commonly called "hobbits" believed to be a homo erectus species that underwent a dwarfism event in an island environment.

An earlier date also makes it necessary to determine why Homo erectus went extinct in Indonesia, although there are many possible explanations, such as the Toba volcano event around 69,000-77,000 years ago (before modern humans arrived) or some similar earlier event in that geologically active region.

And, while we're talking volcanos lets note that iceland's currently errupting volcano has been predictive of its larger neighboring volcano, Katla's eruption within months to a decade afterwards, the last three times it errupted in 920, 1612 and 1821-1823. So it is a good bet that Iceland will have another big volcanic erruption there sometime soon. This is very unlikely to be a Toba class errruption, but it could still be very serious for Icelanders and everyone else in the path of the ash it spews out.

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