Neanderthal Man (37 page)

He asked me if I remembered a small bone that we had gotten from Anatoly Derevianko in Russia (see Figure 22.1). Anatoly is the president of the Siberian branch of the Russian Academy of Sciences and one of Russia’s foremost archaeologists. He had started his career back in the 1960s and was not only very influential in the Russian academic world but also politically well-connected. Over the past several years that we had worked with him I had come to appreciate him more and more, also as a friend. Anatoly has a very warm smile and I have found him always polite and open to collaboration. He is also a very experienced field archaeologist and physically active. In the large lake close to his institute in Novosibirsk he was known to go for kilometer-long swims. Although very different in appearance from my professor of Egyptology, Rostislav Holthoer, who was of Russian descent, Anatoly shares with him the great capacity for friendship and loyalty I find typical of Russians. I count myself very fortunate to collaborate with him.

Some years previously, Anatoly had visited our laboratory and given us a few small bones in plastic bags. They had been excavated in a spot called Okladnikov Cave in the Altai Mountains in southern Siberia, where Russia, Kazakhstan, Mongolia, and China meet. These bones from Okladnikov Cave were too fragmentary to tell what type of human they had come  from, but we extracted DNA from them and showed that they contained Neanderthal mtDNA. Together with Anatoly, we then published a paper in
Nature
in 2007 that extended the range where Neanderthals had lived by at least 2,000 kilometers further east of what had been commonly believed.
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Prior to our paper, no Neanderthal had been confirmed east of Uzbekistan.

In the spring of 2009 we received another bone fragment from Anatoly. His team had discovered that fragment during the previous year in Denisova Cave, another cave in the Altai region located in a valley that connects the Siberian steppes in the north to China and Mongolia in the south. The bone was minuscule, and I hadn’t attached very much importance to it, thinking only that we would see whether it contained any DNA at some point in the future when there was time. Perhaps it would prove to be Neanderthal, which would enable us to gauge the extent of mtDNA variation among the easternmost Neanderthals.

Figure 22.1. Anatoly Derevianko with colleagues. Photo: Bence Viola, MPI-EVA.

Johannes had now found the time to extract DNA from the bone; and Qiaomei Fu, a talented young graduate student from China, had made a library and used a method that Adrian Briggs, the British graduate student in our lab, had developed to fish out mtDNA fragments from the library. They found a very large amount of mtDNA—in total, 30,443 fragments, which enabled them to assemble the complete mitochondrial genome with a very high degree of accuracy. In fact, each position in the mtDNA was seen an average of 156 times, unusually high for an old bone. That was good news, but it wasn’t why Johannes asked me to sit down. He had compared the mtDNA sequence of the Denisova bone to the six complete Neanderthal mtDNA sequences that we had previously determined as well as to mtDNA sequences from present-day humans from around the world. Whereas the Neanderthals differed from modern humans at an average of 202 nucleotide positions, the Denisova individual differed at an average of 385 positions—almost twice as much! In a tree analysis, the Denisova mtDNA lineage branched off well before the modern human and Neanderthal lineages shared a common ancestor. When Johannes calibrated the rate of substitutions by assuming that humans and chimpanzees split 6 million years ago, then the Neanderthal mtDNA split from the human lineage about half a million years ago—just as we had previously shown—and the mtDNA of the Denisova bone branched off approximately 1 million years ago! I could hardly believe what Johannes was telling me. This was neither a modern human nor a Neanderthal! It was something else, entirely.

My head was spinning. What extinct human group could have split off from the human lineage a million years ago?
Homo erectus?
But the oldest
H. erectus
fossils outside Africa were found in Georgia and were about 1.9 million years old. So
H. erectus
were supposed to have left Africa and thus to have split from the lineage leading to present-day humans almost 2 million years ago.
Homo heidelbergensis?
But they were thought to be the direct ancestors of Neanderthals and would then presumably have diverged from the modern human lineage at the same time as Neanderthals. Was this bone from something totally unknown? A new form of extinct human? I asked Johannes to tell me everything about this bone.

The bone was indeed tiny, the size of two grains of rice put together. It came from the last phalanx of the little finger (see Figure 22.2), the outermost part of a pinky, from what was probably a young individual. Johannes had used a dentistry drill to remove thirty milligrams of material from the bone, and from this tiny amount of bone powder he had extracted the DNA that Qiaomei had used to make the library. Given how much mtDNA she and Johannes found, the DNA preservation in the bone must be exceptionally good. I would be back in Leipzig in three days and I told him that we would meet then and decide what to do.

After I hung up, I couldn’t bring myself to listen to presentations about how the genomes of different rat strains differed from each other. It was a sunny and snowless winter day in the New York area. I spent the  morning walking along the windy beach below Cold Spring Harbor and thought about the young person who had died far away in a Siberian cave many thousands of years ago. All that remained of that life was a tiny speck of bone, but it was enough to tell us that she represented something unknown to us, a group of humans who had left Africa before the ancestors of the Neanderthals but after
Homo erectus.
Could we find out what this group was?

When I got back to Leipzig I sat down with Johannes and the others to discuss our next steps. The analyses of the Neanderthal genome were drawing to a close, so people had time on their hands to think about these startling findings. The first thought was whether there could be something wrong with the DNA sequence Johannes had reconstructed. Qiaomei and Johannes had retrieved thousands of mtDNA fragments and much less than 1 percent of them carried substitutions that were suggestive of contamination. Since the mtDNA looked quite different from present-day human mtDNA, it couldn’t be contamination from anyone today. Earlier in my career I had often worried about fragments of mtDNA that thousands or millions of years in the past had become integrated on a cell’s nuclear chromosomes. Such mtDNA fossils could sometimes be mistaken for an actual mtDNA sequence. Fortunately, the circular shape of the mtDNA enables us to separate nuclear mtDNA fossils from real ones. The DNA sequence Johannes had reconstructed from overlapping fragments must have derived from a circular molecule. I didn’t see how our findings could be wrong. Nevertheless, Johannes and Qiaomei would do a separate, independent DNA extraction from some powder that was left of the bone sample and repeat what they had done. But this was more of a formality. I was certain he would get the same results.

Figure 22.2. The small finger bone discovered in 2008 by Anatoly Derevianko and Michael Shunkov in Denisova Cave. Photo: MPI-EVA.

I turned to the question of what this unusual person could have been. If there were more bones in the cave, that could help us figure this out. I was told that Anatoly Derevianko had given us only a portion of the bone so there must be a bigger piece still in Novosibirsk. Perhaps there were also other bones that would give us a hint of what this person could have looked like or that we could use to extract more DNA. We clearly needed to visit Novosibirsk.

I immediately e-mailed Anatoly and said that we had some very unexpected and exciting results and that I wanted to present these to him in person as soon as possible. I said that we would also be very interested in further analyzing the other part of the bone, and perhaps to date it. Anatoly answered the next day and asked for more details about the results. I summarized them for him and we arranged for me to visit Novosibirsk, along with Johannes as well as Bence Viola, a jovial archaeologist of Hungarian descent, in mid-January 2010. Bence specializes in Central Asian and Siberian paleontology, and we had often worked with him in the past. I had just succeeded in convincing him to come to Leipzig from Vienna to work with us and the paleontologists at our institute. A fourth person who would join us was Victor Wiebe. He had done his PhD in Novosibirsk in the ’70s and knew Anatoly and several other people there from that time, and he had been working with me for twelve years. On this trip he would serve as a much-needed interpreter. I had studied Russian thirty-five years earlier, during my military service in Sweden, but by that point I remembered only crude questions one would pose to prisoners of war. They were not suited for scientific discussions.

After a stopover in Moscow and a long overnight flight on to Novosibirsk, we landed in the early morning of January 17. A digital display at the airport terminal showed the time as 6:35 a.m. Then it switched to the temperature: −41°C. When our luggage arrived I opened my bag and put on all the clothes I had. The air outside the terminal was very dry and the snow  was like powder swirling around our feet as we quickly made our way to the car. When I breathed in, the sides of my nose tended to freeze to the septum.

The drive to Akademgorodok took an hour. As the name suggests, Akademgorodok is a city that was built solely for scientific pursuits in the 1950s by the Soviet Academy of Sciences. At its heyday, it housed more than 65,000 scientists and their families. After the collapse of the Soviet Union, many scientists left Akademgorodok and most institutes there had declined. But by 2010, the Russian governments and several large companies had been investing money in the city for almost ten years, and there was a sense of tentative and cautious optimism around the city.

We were housed at the Golden Valley Hotel, which had been converted from a typical Soviet nine-story apartment building. I had visited the hotel once before; one of my most vivid memories from that visit was the lack of hot water, which drove me every morning to walk a good half-hour through the birch forests to swim in a nearby reservoir called the Ob Sea. That, however, was in summer, and I was more than a bit concerned about whether the heating system would work now. I needn’t have worried. When Johannes and I arrived at our room, we found not only was there hot water in the tap but the radiators were so hot that the temperature in the room was unbearably warm—about 40°C. There was no valve to turn the heating down, so we ended up opening the windows and letting in outside air that was almost 80° colder. We kept that window open for the duration of our stay.

We arrived on a Sunday, and our meeting with Anatoly wasn’t until the next day, so after a nap the four of us decided to take a walk. We were amazed to find a small ice cream vendor open for business. Feeling certain that this was the one and only time I would ever have an ice cream when it was −35°C out, I approached the shack. The woman who sold me the ice cream realized that I wasn’t local and urged me to eat the ice cream fast: once it reached ambient temperature, it would be rock-hard and impossible to eat. After quickly eating the ice cream we walked through the frosty forest to the beach where I had swum during warm summer mornings two years earlier. We were the only ones there. The sky was clear but the pale sun provided not even a trace of warmth. Fortunately there was no wind. Even the tiniest bit of air that made it into our clothing had a chilling effect. In fact, by this point my toes were numb and we quickly retreated to our overheated hotel rooms.

The next day we met with Anatoly in the spacious office he enjoyed as head of the Institute of Archaeology and Ethnography. Michael Shunkov,  the archaeologist who led the excavations at Denisova Cave, was also present, as were some of their associates. Johannes presented his and Qiaomei’s findings, and everyone was taken aback. Was this a new form of extinct human, perhaps some form that was present only in Siberia or only in the Altai Mountains? There were in fact several plant and animal species endogenous to the Altai area, so the idea was certainly plausible. Over a lunch of delicious Russian cold cuts washed down with vodka, all served in Anatoly’s office, we excitedly discussed what we might have found. After some time, when the atmosphere was both animated and relaxed, I pointed out that the ultimate answer to our questions would be found in the nuclear genome. If we could sample the remaining, larger piece of the finger bone we would be able to sequence the nuclear genome and get a more complete picture of how this individual was related to people today and to the Neanderthals whose genomes we had just sequenced. At first I didn’t understand Anatoly’s answer to this request, which I blamed on my bad Russian and inebriated condition. But I was still puzzled after Victor’s translation. Anatoly was apparently explaining that he no longer had the other piece of the bone since he had given it to my “friend” about a year ago. Bewildered, I looked questioningly at Victor, Bence, and Johannes. What friend of mine? Did one of them already have it? But they looked as stunned as I was. Then Anatoly clarified. He had given it to “my friend Eddy, Eddy Rubin, at Berkeley.”