What happens in Denisova Cave stays in Denisova Cave... until now
Part 3 of 3: Secrets from the Asian family tree keep making news
Prior posts in this series: Yo mama's mama's mama's mama... etc. and Our African origins: the more we understand, the less we know.
Long before our forebears vanquished and assimilated the Neanderthals and Denisovans, hundreds of thousands of years of the prehistory of modern humans had already occurred within Africa. The fossil at Jebel Irhoud and the latest genetic work both make it clear that the origins of the traits that make anatomically modern humans distinct: the delicate cast of our faces and our long and lean bones, go back more than 300,000 years to disparate regions of Africa. The emergence of H. sapiens more than 200,000 years ago was the culmination of the interaction, admixture and adaptation across these regional evolutionary hearths. Genetics and archaeology are in agreement that the out-of-Africa migration that led to modern humans peopling the whole planet occurred 60,000 years ago, meaning the vast majority of our evolutionary history occurred on our ancestral continent.
But the broader human story goes well beyond just the narrative of our African ancestors, those anatomically modern humans with high foreheads and prominent chins who would go on to occupy six continents. It is also the story of cousins and lost lineages, some of whom persist within our very DNA, while others’ legacy remains only in the archaeological record, their biological lines long since snuffed out. Many of these human cousins were part of a broad Eurasian diaspora that was replenished periodically from African sources, that great reservoir of hominids. The push north and east that began 60,000 years ago was just the last of many migrations outward that had deposited layer upon layer of hominid arrivals across Eurasia for nearly two million years. These earlier migrations gave rise to at least half a dozen different kinds of humans that were there to meet the last African wave, from near cousins who were remnants of earlier groups of modern humans that percolated eastward into Asia, to the more exotic Denisovans and Neanderthals, and finally, strange and distant family members in Southeast Asia who had evolved into dwarf species.
Though the human narrative that led up to our particular modern lineage has been a mostly African story, many of the chapters are to be found in Asia, ultimately left incomplete with the extinction of their protagonists. Today there is only a single human lineage on this planet, but the norm in prehistory was a widely branching and diverse family tree of hominids. Outside of Africa, this was especially true in the southeast corner of Asia, as it stretches out to New Guinea, harboring as many as a half a dozen hominid lineages more than 60,000 years ago.
They found the Hobbits in the ground
In 2004, Australian paleoanthropologists led by the late Michael Morwood discovered a tiny ancient human skeleton on the island of Flores and introduced the world to a new species, the evocatively named Hobbits, or Homo floresiensis. The ensuing debates drew in scientists on four continents, North America, Europe, Asia and Australia. The find even inspired a bizarre 2012 film Age of the Hobbits that depicts the adventures of vegetarian paleo-humans inhabiting Flores, being cannibalized by predatory “Java Men.” Was this actually a new species? Or perhaps the skeleton discovered by the Australian team was simply diseased and deformed? In the first few years, the argument about the Hobbits was as much geopolitical as it was scientific. The late Indonesian paleoanthropologist Teku Jacob confiscated the fossils from Morwood’s team for several years, returning the remains in a damaged state, resulting in as many news stories about the scientists as about the science.