How do we know she was African? Well, the highest density of branches, in other words, of different types of mtDNA, is in Africa. This is extremely strong evidence that all of us, our species, originated in Africa. And it’s not just mitochondrial DNA that reveals this pattern: the Y chromosome, and genes on other chromosomes, also show greater genetic diversity among indigenous Africans compared with Asians or Europeans.4 All this genetic diversity points to Africa being the homeland of Homo sapiens. People have lived there longer than anywhere else, so there has been more time for mutations to accumulate and different lineages to sprout in Africa than on any other continent. In 2008, the results of the most detailed study of human genetic variation to date were published in Nature. Part of the study involved looking at more than half a million points in the nuclear genome, where the individual building blocks of DNA – or nucleotide bases – are known to vary, and comparisons were made between twenty-nine populations from around the globe. Analysis of the differences produced a tree, with branches spreading out from East Africa.5
This genetic piece of the puzzle has not come as a surprise to most palaeoanthropologists; rather, it confirmed what they already suspected from the fossil evidence, because the oldest anatomically modern human remains come from Africa. However, there can always be arguments over the veracity of lineages reconstructed from fossils, because of the patchy and inconsistent nature of the evidence. The story we tell based on palaeontological, and indeed archaeological evidence, is woven together from fragments of information. The likelihood of material evidence, whether of people themselves or cultural objects, surviving for thousands of years and then being found, is minute. Many things made by Palaeolithic societies would have been organic, biodegradable, and so would have little chance of surviving. Very often, pieces of worked stone and waste flakes are the only objects left for us to find. Most skeletons will not become fossilised. They will get crushed or trampled or broken up and leave no trace. For a body to be preserved, it needs to get covered by mud fairly quickly, before it is ripped to pieces by scavengers. And the sediments it is sealed in need to be chemically and physically just right for any bones to be preserved. In many cases, water moving through soil will leach out mineral from the bones, and bacteria will eat away at the protein part of the bones, until virtually nothing is left. In a few lucky cases, the shape of the bone is preserved, while the substance of the bone changes as it exchanges minerals with the surrounding sediment – and it turns to stone, in a word: fossilises.
Even if something is preserved for all that time, there is no guarantee that it will be found. Some fossils and archaeology will be buried deep under metres and metres of sediment, or are in very remote places. Most ancient fossils or archaeological sites are discovered by chance. Often, it is human intervention that lays bare the evidence, through mining, quarrying or road-building, for example. At other times, natural erosion might reveal long-buried fossils. And when that evidence becomes accessible, it still may not be recognised.
Although archaeologists and palaeontologists do try to direct their attention to areas where they think there is a likelihood of finding evidence, sometimes the first clues that lead to significant discoveries are entirely serendipitous.
With all this chance and uncertainty involved in fossil-hunting, it is astounding that fossils have been found, in Africa, that seem to go right back to the dawn of our species.
The Earliest Remains of Our Species: Omo, Ethiopia
For several decades two sites have vied for primacy as containing the most ancient fossils of anatomically modern humans. Both these sites are in Ethiopia: Herto and Omo Kibish.
In 1967, a team led by Richard Leakey had unearthed modern human fossils – two skulls and one partial skeleton – from the Kibish formation in the Omo Basin in Ethiopia. Uranium series dating of mollusc shells in the sediments suggested the fossils dated to around 130,000 years ago. Thirty years later, the fossilised skulls of one juvenile and two adult modern humans were discovered in Herto, in the Middle Awash area of the Afar depression. The skulls looked modern in many ways, but were quite robust. The authors, presenting their finds in Nature, described them as being ‘on the verge of anatomical modernity but not yet fully modern’. The Herto fossils were dated to 160,000 years ago by argon-argon dating.1
But in 2005, new – much earlier – dates were published for the Omo skeletons. A team of geologists and anthropologists, led by Ian McDougall from Australian National University (ANU), revisited the site where the Omo fossils had been discovered. Using site records and photographs, they were able to pinpoint the exact locations where the fossils had been found. At the Omo I site, confirmation that they had indeed located the precise findspot came when they discovered additional fragments of fossilised skull that fitted into gaps in the original finds.2
Both sets of human remains, although found on opposite sides of the Omo River, lay in the same stratigraphic layer. And this layer was sandwiched neatly between two strata formed of volcanic tuff, from the eruptions of ancient volcanoes. This was highly convenient, because tuff is amenable to dating using argon isotopes.
It turned out that the deeper layer was laid down some time after 196,000 years ago, while the higher layer dated to, at most, 104,000 years ago. The layer in which the human fossils were found lay just on top of the deeper tuff. McDougall and his team argued that the fossils were therefore almost as old as this deeper layer of volcanic tuff, at around 195,000 years old. This new date made the Omo fossils the oldest anatomically modern human remains – in the world.
The fossils themselves resided in Addis Ababa Museum, but I wanted to see the place where they had been discovered. It felt like a pilgrimage, and in a way it was: I was going to visit our ancestral home. I had read Richard Leakey’s books as a teenager, and I couldn’t quite believe I was about to get the chance to visit the places I had read about. The names attached to this landscape seemed epic, even mythical, to me: the Rift Valley, the Omo River, Lake Turkana. But they are real places. However, I was travelling to one of the most remote parts of Africa, and finding the precise place where the fossils were discovered wasn’t going to be easy.
On a Monday morning, I set off from Addis Ababa in a small Cessna Caravan, headed for Murule camp (and the closest airstrip to the Omo findspots), piloted by Solomon Gizaw. It was cloudy when we took off, but it soon cleared, and we were flying south-west over green countryside with irregular fields and round, thatched houses of small farming communities. From the air the thatched houses looked like clusters of brown mushrooms. It was clear that agriculture was dominated by small-scale farms, and Solomon was outspoken about the inefficiency of food production in Ethiopia. ‘We have so much good land. There should be more than enough to feed everyone,’ he said. ‘But it is not managed properly.’ Certainly the land beneath us looked green and fertile. It was a very different view of Ethiopia from the terrible pictures of the famine in the 1980s. But there was also little in the way of infrastructure; I couldn’t see many roads. It must have been extremely difficult to reach people out in rural areas when there was a food shortage.
As we flew over the mountains, Solomon explained that we were into coffee country. So when we stopped off to refuel at Jima, I refuelled with some local coffee. The café at the airport was a wooden shack with a corrugated iron roof. Inside, a group of men were playing draughts using a home-made board and bottle tops for pieces. A woman with a beautiful, serene face came over, holding high a tin kettle, and poured a stream of strong, sweet coffee into my china cup.
Then we were back in the air again. The second leg of the journey took us over more wooded hills and valleys. Suddenly, Solomon pointed down at a narrow, shining ribbon: ‘There it is: the Omo River.’
And there it was, meandering southwards through a wide, wooded valley. Then I lost sight of it as we flew up over a ridge of mountains. Solomon handed over the controls of the plane to me, and I followed his directions. ‘Continue straight on down this valley, and t
he Omo will loop round and meet us again on the other side of those mountains,’ he said, pointing to the edge of a ridge in the distance. I flew for about another half an hour, taking the plane down from 5000 to 3500ft, then Solomon took control again as the river reappeared and we approached our destination. We had passed the mountains, and were now flying over a wide, flat flood plain, with the Omo thrown in wide, brown coils across the landscape. Next to the river, the land was densely forested, breaking up into scrubby bush away from its banks. But it was still greener than I had expected. The flood plain was huge. I wondered how Richard Leakey had ever found those fossils.
As we flew lower, I saw a village on a hill looking over a wide arc of the Omo. It was Kolcho, the nearest village to Murule camp, where I would be staying. We circled round and landed at a dusty airstrip where Enku Mulugeta met me in a Land Cruiser. After unloading the plane, Solomon took off again, bound for Addis Ababa; he would return on Friday to pick me up. And I was in the middle of nowhere.
Murule Lodge was situated right on the banks of the Omo, which was wide and greasy-brown here. It was high on its banks and fast-flowing, after recent heavy rains in the mountains. The small houses of the lodge were surrounded by tall trees. Almost as soon as I arrived I heard branches moving above me, then there was a shower of small twigs and leaves. I looked up to see a black and white colobus monkey staring down at me through a forked branch. We made eye contact and then he was away, throwing himself through the trees with amazing speed and agility.
More colobus followed in hot pursuit.
I had been expecting a very basic camp, so my little house at Murule came as a very pleasant surprise. The windows were covered in mosquito screens, with curtains inside and raffia blinds outside. There was a large room in the house, with a double bed, a crude wooden chair and a sill wide enough to hold my bag. A single lightbulb hung in the corner of the room, but there were also pots of sand on both sides of the bed, with candles and matches. (Electricity was an occasional luxury here, powered by a generator for just a couple of hours after sunset.) I even had a bathroom, square and concrete, with a flushing toilet, a sink and a shower fitting in the ceiling. Admittedly, the shower was unheated, untreated water straight out of the Omo, but it was all so much more luxurious than I’d anticipated for this remote place in the middle of the Rift Valley – even if I was sharing the place with a few geckos and a strange-looking spider with a penchant for hiding inside toilet rolls, a ploy destined only to scare the life out of both of us.
I fixed up my mosquito net. It was late afternoon and the mosquitoes were just starting to bite. As night fell, I sat out on a wooden chair looking over the Omo, with a packet meal and a bottle of locally brewed St George beer. I was being extraordinarily careful with food and water here: consuming nothing unless it came out of a packet or a bottle. We were too far away from anywhere to take any risks, and I didn’t want to jeopardise my one chance of visiting the site where the Omo fossils had been found. I turned in around ten; I had an early start the next day, and I knew it was going to be tough.
I slept well that night, despite the sticky heat and the noisy wildlife. I woke up a couple of times to hear things moving about outside and colobus monkeys barking in the trees above. By 5.30 a.m. I was up and about, as were a vast range of different birds, judging by the Omo dawn chorus. I packed a rucksack with essentials: medical kit, some cereal bars, camera, Ventolin inhalers, notebook, GPS and map, as well as several boxes of crayons and a selection of small toy cars. I filled my Camelback reservoir to the brim, and I took an extra two-litre bottle of water as well. Then Enku and I set off in the Land Cruiser to catch a boat across the Omo.
After a bumpy ride along a dusty dirt track, we pulled up next to the riverbank, opposite the village of Kangaten. We waved at the boatman on the other side, and he brought his boat across. It was small, with a modest outboard motor, but its skipper knew how to beat the swift current by taking it in a wide arc, heading upriver first then falling back alongside us as he approached the near bank. I scrambled into the boat and off we went again, over to Kangaten. I had seen crocodiles in the Omo as I’d flown in, and when I asked the boatman if there were any around he smiled and nodded. I didn’t see any, although the odd log drifting down the river made me look twice.
On the other side, it seemed as if most of the village had turned up to greet us. Lots of children swarmed around. I took photographs and they clustered around me, squealing in delight as I showed them the photos on the camera. They pointed and laughed as they recognised each other in the tiny screen. Before Enku and I embarked into the four-wheel-drive that was waiting for us on this side of the river, I handed out coloured wax crayons and toy cars. Some of the kids looked healthy, but others displayed the swollen bellies and stick-thin legs of malnutrition. I also spotted patches of skin infection and ringworm on their bare bodies and faces. They were much less healthy than the children in the Bushmen village. I felt as though I should have brought medical supplies and food rather than crayons and toys. I also felt that familiar pang of guilt that I was an academic, not a practising medical doctor any more. At such times I have to remind myself that teaching and research are worthwhile. And I know that Ethiopia’s problems can’t be solved by aid workers alone. I handed out my cereal bars and got into the car.
Enku introduced me to Soya, who would act as my translator when we reached the village of Kibish. I knew that people from that village had been involved with the dig and discoveries at Omo, and that, more recently, they had helped Ian McDougall and his team when they visited the site. Although I had the map and the coordinates published by McDougall, I was aware that I might end up going hugely out of my way in the bush if I tried to find the site on my own, without help from locals who knew the landscape and the paths through it. And I really didn’t want to get lost in the bush. Another issue was security. The tribes around the Omo River – the Mursi, Bumi, Hamer, Karo, Surma and Turkana – seemed constantly to be fighting each other, and there were a lot of men wandering about with guns.
After a further drive along dusty tracks through the bush, having stopped to talk to a group of men with guns who were apparently local police, we reached Kibish. The huts of the village were surrounded by a dense thorny fence, with a slit-like entrance that was hard to discern but presumably excellent for keeping out hyenas or other tribesmen. Soya led the way and took me to the chief, Ejem. Most people in the village seemed to be dressed fairly traditionally. The women wore knee-length apron-like skirts, and masses of bead necklaces on their bare chests. Many had red ochre painted on their chests, necks, faces and braided hair. Smaller children ran around naked. Older ones had painted faces and cloths tied loosely round their waists. One boy was wearing a faded, red David Beckham T-shirt. Some men were dressed traditionally, with small skirts and collars of beads, but the chief, Ejem, was wearing flamboyant basketball shorts, a plastic leopard-print cowboy hat and a necklace of red and yellow beads. His status was made obvious by the wearing of these exotic items.
With Soya translating, I introduced myself to the chief and asked him if anyone knew the place where the fossils had been found. Ejem called over one man and pointed to him. Soya translated. ‘Here is one man, the other is coming.’ This first man, Kapuwa, was wearing a T-shirt and a brown cloth hat with a turned-up red brim, and carrying a gun. He talked to Soya and I grew excited as he pointed off into the distance and made digging motions with his hands.
‘Soya, what did he say?’
‘He said, “There was someone with a camera and someone was digging. He found something like a bone, which had stayed there for a long time. I know exactly the place and I can show you now.”’
The second guide, Logela, had now come over as well. He was wearing a yellow cloth hat, set at a jaunty angle on his head.
So Kapuwa, Logela, Soya and I headed off into the bush. We drove for about 4km away from Kibish, through flat, scrubby bush, until we reached an area with dune-like hills and deep channels: the K
ibish formation. It was impossible to take the car any further. I waymarked the car on the GPS before striking out into the wilderness. Even though I had started as early as possible that morning, I was still having to walk in the heat of the midday sun. And Logela and Kapuwa set a fairly intense pace. Logela was carrying a gun, and I asked Soya how often violence broke out between tribes.
Apparently it was a fairly common occurrence, but, as we weren’t after anyone’s cattle, we ought to be safe. It was still just as well to have a gun, though.
‘Did you see the scarification on the chief’s chest?’ Soya asked me. I had. ‘It means he is a hero: he has killed a man.’
As we walked, we did meet a couple of other lone men with guns, and I was very grateful for the security of travelling with Soya and the guides from Kibish. And they did seem to know where they were heading. We walked down through the barren valleys of the Kibish formation, which was like a lunar landscape. Then we were on the flood plain again and close to the Omo. As we tracked up the west bank of the river, I started to feel heady and overheated, and so we stopped for a while. We had been going for about an hour, and the sun was now at its highest point, directly overhead and beating down. I drank more water and wrapped a silk scarf around my head, then we carried on. We passed a ridge, perpendicular to the river, and the guides pointed to another, similar ridge. Soya told me that they thought we were almost at the spot. I was very glad; I was starting to feel as if I might have to turn back without reaching the site, but now I knew we were close I could summon the determination to carry on.
The Incredible Human Journey Page 6