Visiting Dmanisi, Earliest Hominin Site Beyond Africa

**Admin** Sam 10 Sep 2016 - 7:16

Visiting Dmanisi, Earliest Hominin Site Beyond Africa
By Gemma Tarlach | June 10, 2016 12:45 pm

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In a quiet corner of the Republic of Georgia, hidden beneath medieval and Bronze Age ruins, the hominin fossil jackpot of Dmanisi is rewriting the story of human evolution. All photos credit: G. Tarlach

Pop quiz, hotshot: what are the most significant fossil sites for piecing together the story of human evolution?
Your list probably included Tanzania’s early hominin-rich Olduvai Gorge and Hadar, Lucy’s hometown in the Afar region of Ethiopia. Maybe you thought of the Rising Star cave system, which hogged hominin headlines last year with the announcement of the Homo naledi finds within. Or you went old school, naming Trinil, where a young Dutchman uncovered Java Man, akaHomo erectus, more than a century ago.
Was Dmanisi on your list? It should have been, arguably near the top. The sheer age of the multiple hominin fossils from Dmanisi — about 1.8 million years old — has already challenged the conventional timeline for when the first members of our genus left Africa. And there is much more to discover.

Situated on a promontory overlooking the confluence of two rivers in a bucolic corner of the Republic of Georgia, Dmanisi is one of the world’s richest and most intriguing fossil sites for hominins. Yet it remains largely under the radar outside academic circles. That’s a shame, because what researchers have uncovered there over the past 25 years rivals other, more famous sites.

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Angry Dmanisi hominin (reconstruction of Skull 5 at the Georgian National Museum in Tbilisi) wants some respect.

The Dmanisi Five

For starters, researchers have unearthed five hominin crania, each with a different story to tell. D3444, for example, belonged to an elderly adult, and the associated jawbone is missing all its teeth. The individual was toothless and unable to chew, in fact, for the last several years of life, which suggests survival was only possible with some help. That implies community and society.
Then there’s the famous Skull 5, which is generally the fossil you’ve seen if you’ve seen anything from Dmanisi. Spectacularly complete and beautifully preserved, Skull 5 doesn’t look much like the other four crania, with its massive brow ridge and robust, protruding face. Believed to belong to a male, Skull 5 also has the smallest braincase of the five individuals. It’s so different from the other crania that some researchers have suggested it must be a different species.
The Dmanisi team, however, believes all the individuals found at the site belong to a primitive form of H. erectus. I have heard some speculation that Dmanisi hominins may have evolved from an early, unknown (and certainly unexpected) African exodus of Homo habilis, the first known member of our genus, which evolved in Africa around 2.5 million years ago. But the truth is, the Dmanisi bunch don’t fit neatly anywhere into our expectations of early Homo.

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Casts of the five Dmanisi crania and associated mandibles, the hominin pride of Georgia, on display at the national museum in Tbilisi. Robust but small-brained Skull 5 (right) dwarfs elderly, toothless adult D3444 beside it.

According to the conventional timeline for the rise of genus Homo, H. erectuswas just getting its act together in Africa, where it evolved, at about the same time that hominins were already calling Dmanisi home, trying to survive and not get eaten by the various predators around, including Etruscan wolves and saber-toothed cats.

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Etruscan wolf, one of many things that could kill you 1.8 million years ago. Fossil from Dmanisi now on display at the Georgian National Museum.

Of the thousands of animal bones found at Dmanisi, both predator and prey, none belong to African species (aside, of course, from the hominins). That means the hominins at the site had to have adapted to a new environment with different fauna, as well as a colder climate with distinct seasons, apparently without fire or advanced stone tool technology (evidence of neither has turned up so far).

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Credit: Rasbak/Wikimedia Commons

The ability to live one continent north of where we’d expect to find them 1.8 million years ago is just another intriguing puzzle about the Dmanisi hominins. Although their post-cranial (below the neck) skeletons were fairly modern, they had brains the size of a bocce ball, as one long-time Dmanisi researcher puts it.
Think about what their presence at Dmanisi says. It’s basically sticking out your tongue and going “nyah-nyah-nyah” at the decades of assumptions that only fancyman H. erectus, when fully evolved, had the brains and the tools and the fire required to make it out of Africa and survive.

http://blogs.discovermagazine.com/deadthings/2016/06/10/visiting-dmanisi-earliest-hominin-site-beyond-africa/#.V9OWcZiLRYg