Three papers, published together in Science today, add up to a paradigm-shoving conclusion: Key aspects of what we think of as modern human behavior evolved more than 300,000 years ago, a radical revision to the evolutionary timeline.
To understand the significance of the trio of studies, let’s take a brisk walk through recent changes in our understanding of human evolution. For decades, the consensus was that Homo sapiens evolved around 200,000 years ago in Africa, with anatomically modern humans emerging 100,000 years ago and leaving their ancestral continent around 50,000 years ago.
In the past few years, however, a series of surprising fossil finds, as well as advanced genetic analysis, have smashed that old paradigm like an angry Hulk.
The new picture of human evolution just emerging is that our species is more than 300,000 years old and left Africa much earlier than we thought, beginning at least 120,000 years ago and possibly as early as 200,000 years ago. Genetic analysis suggests our species may be even older, and was already interbreeding with Neanderthals, up to 470,000 years ago.
Fossilized bones, and the ancient DNA researchers are sometimes able to extract from them, can only tell us so much, however. Often missing from the picture is how the individuals lived. While the timeline for the physical evolution of our species gets pushed further and further back, Homo sapiens are defined as much by their modern human behavior as the shape of their skull. Any early Homo sapiens running around might have looked at lot like us, the thinking went, but they didn’t act like us and weren’t capable of the same cognitive feats, such as symbolic thinking.
While there was no definitive date for the emergence of modern human behavior — after all, it was a process, not the flip of a switch — the nice, round number of 100,000 years ago has often been cited as a landmark. That’s about when some of the earliest evidence of modern human behavior, such assembling ochre-based compounds to create paint kits, appears.
Enter today’s studies, which take a multifaceted look at the Kenyan site of Olorgesailie. Taken in sum, the papers present evidence that gradual climate change drove humans to adapt to a new environment and altered food supply; the adaptations appear to include far-flung social and trade networks, advanced tool technology and manipulation of ochre, a variety of high-iron rock used throughout the human story as pigment. [Continue reading…]
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