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The Dmanisi Site

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National Geographic April 2005 Caption for four dmanisi skulls: The four Dmanisi skulls may be just the tip of an archaeological iceberg. 'At the rate we are going,' says scientist Reid Ferring, 'dozens of early humans could be found at Dmanisi.' Text adapted from the National Geographic Magazine, April 2005

Bones and crude stone tools from Dmanisi allude to a brutal chapter in early human's campaign to move up the food chain. 'This was likely a hunting ground for lots of predators' says paleoanthropologist Martha Tappen, noting that the site had water on three sides, creating a cul-de-sac that would help trap prey. Tappen has spent four summers studying fossil bones from the site, including a bone fragment, left at top, probably from a deer. The stone tool found with the bone was found nearby. Telltale marks on the bones show that the Dmannisi people used stones to butcher animals, says Tappen. They also provide the earliest evidence of carnivorous hominins in Eurasia and support a theory that eating meat allowed early humans to survie in northern latitudes, where plant foods might be scarce in winter. Whether the site was a seasonal camp or a permanent base is unclear. With sabre-toothed cats lurking, says Tappen, 'it might not have been safe for the humans to sleep there.' ************************ ************************** DMANISI FIND BY JOSH FISCHMAN PHOTOGRAPHS BY KENNETH GARRETT ART BY JOHN GURCHE Across a dusty courtyard at the Georgian State Museum, up three flights of'stone steps, and down a long hallway, humanity's distant past lies waiting. On a table in a highceilinged room rests a replica of a skull, empty eye sockets peering over the plaster wrapping around the lower face. 'But let me show you the real thing,' says David Lordkipanidze, a paleoanthropologist and the director of the museum in Tbilisi, capital of this former Soviet republic. Lordkipanidze slowly lifts the lids of four wooden boxes, one by one. Inside are bare skulls, nearly 1.8 million years old. 'Here, this is our teenager,' he says. The skull does look youthful, with small, even graceful features, some of the teeth not yet fully grown in. 'And this is what we're calling the old man' he continues. Again, the skull is humanlike but small. But the remarkable feature is the mouth. Not only are there no teeth, but nearly all the sockets are smooth, filled in by bone that grew over the spaces. The jaws look like two crescent moons. Although it's hard to be sure of his age, 'it looks like he was maybe about 40, and the bone regrowth shows he lived for a couple of years after his teeth fell out,' says the anthropologist. 'This is really incredible. ' How did the toothless old man survive, unable to chew his food? Maybe his companions helped him, says Lordkipanidze. If so, those toothless jaws might testify to something like compassion, stunningly early in human evolution. You have to flash forward more than one and a half million years, to the Neandertals of Ice Age Europe, to see anything comparable. He smiles and spreads his arms to encompass the old man, the teenager, and two more skulls. 'We hit the jackpot.' Lordkipanidze and his colleagues hit it in a very unexpected place: not in Africa, home to famous fossils like Lucy and famous sites like Tanzania's Olduvai Gorge, but well to the north, in Georgia, where Europe ends and Asia begins. Found in the shadow of a ruined medieval castle near the small town of Dmanisi, the four skulls and other bones provide a rare snapshot of what could be a single population of hominins, as anthropologists now call humans and their ancestors. Most hominin fossils are isolated individuals, but having a collection of them lets researchers study the range of age and body size within a single group. It's a group that had a key role in human evolutionary history. The human ancestors found at Dmanisi - early members of a species called Homo erectus - appear to be the first hominins to have left Africa, where our evolution began. They were short and small-brained, seemingly ill-suited to travel. Yet they evidently had advantages that outweighed their physical shortcomings: a new way of life based on hunting or scavenging and, Lordkipanidze and his colleagues think, a new kind of social cooperation. In the survival of the old man, 'we're looking at perhaps the first sign of truly human behavior in one of our ancestors,' says Lordkipanidze. It could be a glimpse of a new level of planning and sharing, adds Philip Rightmire, an anthropolo- gist at Binghamton University in New York State who is on the Dmanisi research team. 'Seeing this at the very dawn of Homo, our own genus,' he says, 'may be the most exciting thing of all.' The ancient site lies on a wooded plateau a short walk from Dmanisi. Two rivers flow through deep gorges on either side of the plateau before meeting at its tip, where the land rises like a prow over fields and pastures. Almost two million years ago, before the hominins moved in, a series of volcanic eruptions flooded the site with lava, which hardened into basalt. Later, more eruptions dumped tons of ash on top of the rock. In between those catastrophic rains of ash, life crept back onto the plateau, including hominins who lived and died there. Buried by later ashfalls, their bones lay entombed until the 1990s, when archaeologists excavating the medieval ruins began finding very old bones beneath the crumbled cellars. The layers of basalt and ash are key to dating the fossil deposit. Rocks contain tiny grains of magnetic material that record the direction of the Earth's magnetic field at the time they hardened. At Dmanisi, the magnetic grains give anthropologists a clear time benchmark. While the grains in the basalt and the oldest ash layers point north, those in the ash on top point south because the Earth's magnetism reversed after the lava flow but before the last ashfall. That magnetic flip took place 1.78 million years ago. The lava flow and ashfalls must have taken place in quick succession, says Dmanisi researcher Reid Ferring, a geologist and archaeologist from the University of North Texas. 'The rock underneath isn't weathered,' he notes, 'so it was covered up before the rain and wind could get to it.' Human ancestors occupied the site after the magnetic flip, during a short lull in the eruptions' 10 000 years at most , Ferring says, 'and maybe as little as a few hundred! True, it's enough time for the four individuals unearthed there to have lived generations apart. But they occupied the same small patch of ground. 'Look at this:' says Ferring, standing in a pit about 20 feet deep at the excavation. It's called the Champagne Room because this is where the overjoyed excavators unearthed the skulls. 'We found one jaw over here' -Ferring plants his boot on a patch of dark dirt,, and one skull just over here'-he points with his other foot to a spot just a few feet away. 'If yo lie down right, you could play a game of Twister on these bones. That's how close they were.' Ferring pauses. 'You know, it's even possible that some of these folks knew one another.' Even if they didn't actually set eyes on one another, a handful of individuals living at the same site in a relatively short time span can be thought of as a population, a group that closely shared genes and lifestyles. At places like Olduvai, individual fossils are so far apart in timehundreds of thousands of years or more-that scientists argue over whether differences among them indicate different species or just the kind of variations you might see among people today. At Dmanisi, for the first time, anthropologists are getting a good look at a population, young and old. They're starting to appreciate just how much variety can crop up within a single group. And the range of features they're seeing is helping them fit Dmanisi into humanity's evolutionary odyssey. Many of those features resemble those of David Lordkipanidze (fourth from left) and fellow scientists carry a crate holding a 1.77million-year-old human cranium-the toothless 'old man'-dug up in 2002 near Dmanisi, in the Caucasus Mountains. The site has yielded a rich array of Homo erectus bones. Homo erectus, the first well-traveled hominin, found both in Africa and far across Asia. Straight browridges, a line of heavy bone running frontto-back across the top of the skull, and the shape of the nasal cavity all link the Dmanisi skulls to classic erectus fossils from hundreds of thousands of years later and thousands of miles away known as Java and Peking man, from Indonesia and China, as well as fossils from Kenya. But some telling differences suggest that Dmanisi was more than a way station for Homo erectus. The Dmanisi skulls are small for erectus and rounded instead of angled at the back, traits reminiscent of an earlier species, Homo habilis, or 'handy man', which appeared in Africa before two million years ago. 'My feeling is that we can say this is something between habilis and erectus, and maybe it's the founder of erectus,' says Lordkipanidze. That would make Dmanisi the true starting point for the journeys of Homo erectus. Here is how events might have unfolded: Dmanisi-like hominins evolved from Homo habilis in Africa by about two million years ago. Almost immediately they wandered out of Africa and through the Middle East to Georgia, completing the transition from habilis into erectus. Then they branched out. Some, the forerunners of Peking man and Java man, went on to East Asia and Indonesia. Others doubled back to Africa, where lanky and somewhat more slender African versions of erectus - which are also known as Homo ergaster - emerged later. In the end these erectus variants gave rise to modern humans, who ultimately set out on global journeys of their own. In that picture, human ancestors first took to the highway hundreds of thousands of years earlier than anthropologists used to think - and well before they seemed ready to make the journey. Forms of Homo erectus that appeared in Africa by 1.8 to 1.5 million years ago were once believed to be the first wanderers in our family tree, leaving Africa as recently as a million years ago. These hominins looked like capable travelers. They had long legs, good for covering a lot of ground, with some skeletons about six feet in height. They were technological innovators, developing the first hand axes and other sharpedged stone tools by 1.5 million years ago. And they had a brain size averaging about 900 cubic centimeters, much bigger than anything previous and approaching today's average of 1,350 cubic centimeters. Compare that with the runty group at Dmanisi, where one individual barely topped four-and-a-half feet. They had an average brain size of 650 cubic centimeters, much closer to creatures limited to Africa, like Homo habilis. And tools? Nothing special - just stone flakes dislodged by knocking rocks together, as human ancestors had been doing for hundreds of thousands of years before Dmanisi. How, one can be forgiven for asking, did they ever get out of Africa? 'I think they may have followed a trail of carcasses' says paleontologist Lorenzo Rook, a team member from the University of Florence in Italy. At the time predators like saber-toothed cats were invading new territory, such as Asia. Big carnivores tend to bring smaller meat-eating creatures with them, hangers-on that are drawn to the leftovers of a kill. Among them might have been hominins that had adopted a new feeding strategy: eating meat. 'When you come to meat-eating as a reason for getting out of Africa, it works pretty well,' says Martha Tappen of the University of Minnesota, who studies the animal bones at Dmanisi. 'Why couldn't Lucy and creatures like that make it out of Africa? They were largely vegetarian. Up in Georgia it's seasonal. You can't get fruit year-round. So you have to switch to meat with veggies.' Dmanisi, she adds, was a natural steak house. 'Ifs a great animal trap-this tip of land surrounded by water. So Bambi wanders out, and sabertooth is there waiting. There's nowhere to run. Hominins could have joined the hungry scrum. The animal bones from the site include extinct forms of big cats and bears, small wolves, ostriches and other birds, horses, deer, and giraffes. Hominins clearly dined on some of the gentler creatures, says Tappen. 'I've found a handful of cut marks on animal bones, made with stone tools.' They are 'clear signs of butchery,' she says, and could indicate that the Dmanisi hominins were killing animals and stripping meat from their bones rather than just scavenging what other carnivores left behind. Bigger predators may have dined on the hominins themselves: Chew marks appear on at least one of their bones. 'Maybe they were trapping, and also getting trapped,' Tappen says. Human ancestors 'were not at the top of the food chain yet.' That's why scientists aren't sure what to make of the caches of river stones that turned up near the hominin bones. Maybe the Dmanisi people hurled the stones at small game. But given their perilous existence, they might have been hoarding stones for defense against lurking predators-or for driving the predators away from carcasses so that they could scavenge the remains. It's tempting to imagine human ancestors living furtive, fearful lives at Dmanisi, competing with creatures that could kill them with a swipe of a claw. Yet this risky shift to eating meat also may have put our ancestors on the road to becoming the planet's dominant species. 'Predation is a big evolutionary force,' Tappen says. 'It drives a lot of changes in anatomy and behavior. One thing we know is that predators get smarter than her- bivores. ' It takes more planning to hunt or scav- enge than to pluck fruit. 'So [meat-eating] might be leading to larger brain sizes:' And more brainpower might have led to sophisticated group behavior, which could explain the survival of the 'old man.' After losing his teeth, he might have fended for himself for a while, using stones to mash up softer plants as well as scraps of meat. 'But remember this place has seasons, so plants aren't always there,' says Ferring. The slowmoving elder probably could not support himself through the winter by hunting or scavenging. To survive, Ferring thinks, he probably had to rely on his companions to bring him small pieces of meat. There are hints that a crippled Homo erectus might have received similar help in Africa about 1.7 million years ago. But there's no other sign of prehistoric compassion as clear-cut as the Dmanisi oldster's smooth jaws until the Old Man of La Chapelle-aux-Saints, a Neandertal skeleton from 60 000 years ago with many missing teeth and crippling arthritis, who definitely needed help to survive. Lordkipanidze admits that his interpretation of the Dmanisi discoveries is far from certain. 'What we are doing is like reconstructing a crime scene' says Lordkipanidze, who as a boy loved mystery novels-Agatha Christie and Arthur Conan Doyle. 'The crime was long ago, and you can't find witnesses.' That leaves only the clues from the ground, and some anthropologists believe they tell a different tale. These skeptics think the old man could have found enough to eat on his own, and they aren't convinced that the Dmanisi fossils represent the very beginning of the Homo erectus line rather than an offshoot. A few even question whether the fossils belong to a single group at all. The doubts focus on a massive jaw from the site, much bigger than the other fossils. It could simply have come from the biggest guy in town. Or it could be a sign that Dmanisi was home to two hominin species. But if the clues add up the way Lordkipanidze thinks, Dmanisi offers a glimpse of humanity's deepest roots. Marc Meyer, a graduate student from the University of Pennsylvania who has worked at Dmanisi over several years, remembers the awe he felt as he dug for clues to our beginnings. 'When you see the yellow of a bone, you first think, I've got to slow down. It's just this yellow flash, and you think, This could be my ancestor.'

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