At Eurekalert (June 29, 2011), we learn: "Finding showing human ancestor older than previously thought offers new insights into evolution." In the current episode, new excavations in Indonesia and dating analyses show that modern humans never co-existed with Homo erectus. The find counters previous hypotheses – which it must, in order to qualify as an episode:
The new story supports the "multiregional" model of human evolution.
Homo erectus is widely considered a direct human ancestor—it resembles modern humans in many respects, except for its smaller brain and differently shaped skull—and was the first of our ancestors to migrate out of Africa, approximately 1.8 million years ago.
Homo erectus went extinct in Africa and much of Asia by about 500,000 years ago, but appeared to have survived in Indonesia until about 35,000 to 50,000 years ago at the site of Ngandong on the Solo River. These late members of Homo erectus would have shared the environment with early members of our own species, Homo sapiens, who arrived in Indonesia by about 40,000 years ago.
The existence of the two species simultaneously has important implications for models about the origins of modern humans. One of the models, the Out of Africa or replacement model, predicts such overlap.
However, another, the multiregional model, which posits that modern humans originated as a result of genetic contributions from hominin populations all around the Old World (Africa, Asia, Europe), does not. The late survival of Homo erectus in Indonesia has been used as one line of support for the Out of Africa model.
However, findings by the SoRT Project show that Homo erectus' time in the region ended before modern humans arrived there. The analyses suggest that Homo erectus was gone by at least 143,000 years ago—and likely by more than 550,000 years ago. This means the demise of Homo erectus occurred long before the arrival of Homo sapiens.
Interesting. In this version, homo sapiens does not murder homo erectus.
The spread for the exit of homo erectus from the scene is 400,000 years. A bit fuzzy in the frame, don't you think?
Some other episodes linked here.
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Denyse O'Leary is co-author of The Spiritual Brain.