Last week, in Nature, University of Iowa anthropologist Russell Ciochon and colleagues published new dates on fossils and sediment layers from a site called Ngandong that originally yielded a dozen or so Homo erectus skulls in the 1930’s. Using uranium-series dating on some newly excavated mammalian remains from the same sediment layer as the Homo erectus skulls, the researchers surmised that the bone bed is between 117,000 and 108,000 years old. This new date challenges dating done in the 1990s that suggested the bone bed was between 53,000 and 27,000 years old.
This evidence make the Ngandong specimens the current last-known fossils of Homo erectus in the world. Sure, there fossil record is patchy and in the future younger, more recent H. erectus fossils may be found. But, from this we can begin to understand two things.
First, from this timeline, we gather that the Ngandong Homo erectus went extinct, at least in Indonesia, long before Homo sapiens made it that far. About the time these specimens died, Homo sapiens was in the Levant. It wasn’t until 73,000 years that our species made it to Southeast Asia! Just where and when the Denisovans meet Homo erectus is up to a lot of speculation.
Second, from this timeline, we can see Homo erectus extinction occurred during the end of the last interglacial Ice Age, when the climate changed to a warmer and wetter environment. Homo erectus on Java lived in woodlands for 1.5 million years. This ecosystem changed for the Ngandong individuals, as their world was changing from the cool and dry environment to floods washed them downstream in a flood.