Neanderthal Man (38 page)

I have no idea how I looked or what I said after that. I knew that Eddy had been trying to get his hands on bones to sequence the Neanderthal genome ahead of us. But here we were learning that, for almost a year, he had had a much larger piece than we did of this particular bone that contained so much endogenous DNA that it would be possible to sequence the nuclear genome in a matter of a few weeks, without technical tricks or many hundreds of runs on sequencing machines. And we were still weeks from even submitting our Neanderthal paper to
Science,
let alone its publication. My recurring worst worry suddenly seemed about to come true: before we could publish there would be a paper from Berkeley presenting the genome of another extinct form of humans, sequenced to even higher coverage than the Neanderthal genome. Who would then care about our years spent painstakingly working on extraction techniques, on enriching for endogenous DNA, on teasing out the Neanderthal DNA from the vast excess of bacterial DNA? All these details would be important in the long run for use on  the hundreds of bones that weren’t as miraculously well preserved as this one, but in terms of getting the genome of an extinct human relative, Eddy would have done it faster and better, simply because he got lucky.

I struggled to regain my composure and to say something that wouldn’t give my feelings away. But I managed only some mumblings about scientific collaboration. We soon left the meeting with a plan to meet our hosts for dinner later at the House of Scientists, the social center of Akademgorodok. Walking back to the hotel room, I didn’t feel the cold anymore. Johannes tried to console me. He tried to make me see that we should just continue doing the best work we could and forget about the competition. He was right, of course. But obviously we shouldn’t drag our feet. Now, more than ever, we had to be fast.

Dinner was an ebulliently friendly affair, as were all the dinners I have enjoyed with Anatoly. The food was excellent: salmon, herring, and caviar were followed by several delicious main courses. Toasts with good vodka were frequent throughout the evening and, as is customary in Russia, each dinner participant took his turn proposing a toast to some commonly appreciated theme, such as collaboration, peace, our teachers, our students, love, women, and so on. When I had first started traveling in the Soviet Union, I had loathed this custom, feeling immensely embarrassed when I had to mumble my way through a speech on a theme I didn’t enjoy talking about in front of a large dinner crowd. With time, though, I had gotten used to it and had even come to appreciate the fact that it allowed all participants at the dinner, even those whose social standing would not normally have allowed them to be heard, let alone dominate the conversation, to command everyone’s undivided attention for a short time.

Undoubtedly I also had come to appreciate this custom thanks to the fact that, deep down, I’m a very sentimental person, a trait that alcohol often helps bring to the surface. And sentiments are what these toasts are about. I toasted, first, to our very fruitful collaboration and then to peace, pointing out how I had grown up in capitalist Sweden, and had been conditioned to regard a huge war in Europe as a likely scenario and Russia as our natural enemy. Since Sweden was officially neutral, the potential enemy I had been trained to face during my military service was officially and euphemistically named “the superpower,” but tellingly, the language spoken with prisoners during our war games was Russian. But the war everyone planned for never came. We never had to face each other as enemies. Instead we were sitting here as friends, working together and discovering amazing things together. Thanks to the alcohol, I was moved by my own words. As one of the youngest at the dinner, Johannes appropriately chose  to toast his teachers. I realized how inebriated I was when he brought tears to my eyes by saying that he had two fathers in science: me, who had introduced him to molecular evolution and ancient DNA, and Anatoly Derevianko, who, during two field trips to the Altai and Uzbekistan, had introduced him to archaeology. In fact, I was so moved because these were truths that we wouldn’t normally share with each other.

We walked to our hotel after dinner along the main street of Akademgorodok. The night was very cold and dark, and the stars unbelievably bright due to the fact that the ice-cold air could hold hardly any humidity. But I didn’t notice. The tension from earlier in the day had caused me to down shots of vodka faster than I normally would have. In fact, I had the feeling that I hadn’t been so drunk since my teens. But as we unsteadily made our way down the snowy street, Bence told me something that instantly penetrated even my intoxicated mind. Earlier in the visit, Anatoly had given him a tooth that had been found nine years earlier in Denisova Cave. It was a molar (see Figure 22.3), probably from a juvenile, but it was huge. Bence said that he had never before seen a similar tooth, seeming unlike both Neanderthal and modern human teeth. In fact, he said, if he hadn’t known where it had been found, he would have thought that it had come from some much older human ancestor, maybe
Homo erectus
in Africa, or
Homo habilis,
or maybe even
Australopithecus.
It was the most amazing tooth he had ever seen. In our drunken state, we were sure that it must have come from the same person as the finger bone, and we felt certain this creature must really have been something we hadn’t seen before. In the Altai, there have long been rumors of mountain-dwelling snow men called Almas. As we made our way toward the hotel, we shouted that we had found an Alma! We joked that, if we could get a radiocarbon date from the tooth, we might find it to be just a few years old. This would explain why it contained so much DNA. Maybe these Yeti-like creatures were still living somewhere on the border between Russian and Mongolia. I don’t quite remember finding our hotel room and getting into bed that night.

The next morning it was difficult to get up to catch the taxi to the airport, and none of us spoke much until an hour or two into our flight to Moscow. By then, the bleak reality of our situation was slowly dawning on me, tainted by the dreariness and cold sweat of a serious hangover. Maybe they were already writing a paper in Berkeley on the Denisova bone. We had started writing a paper on our Denisova mtDNA results over Christmas, but it was now urgent that we finish this paper as soon as possible. Where  would we submit it? The editors at
Science
were already impatiently waiting for our Neanderthal genome paper. To approach them about a different paper on a different topic might make them write us off as unable to finish one project, let alone two. So we decided to contact
Nature.
During a long layover at the airport in Moscow, I wrote an e-mail to Henry Gee, the senior editor who handles paleontology at
Nature,
and to Magdalena Skipper, the editor who handles genomics. I told them that we had a paper almost finished that described “what we interpret as a new hominin species based on a complete mitochondrial DNA sequence that diverged from the human line about twice as long ago as the Neanderthal mtDNA.” I was all too aware that the publication process could drag on for many months. It could even end in rejection, after months of dithering with reviewers and editors, after which we would need to submit to another journal and endure another similarly lengthy process. I didn’t want that to happen this time so I told them that we had direct competition and would be grateful if the paper could be handled quickly. An hour and fifteen minutes later, Henry Gee replied with “How exciting! Prediction is very hard, especially about the future. However, when you send it in, we’ll give it topmost priority.”

Figure 22.3. The Denisova molar. Photo: B. Viola, MPI-EVA.

As soon as we were back in Leipzig we finished the manuscript, which we entitled “The Complete mtDNA Genome of an Unknown Hominin from Southern Siberia,” and sent it off to
Nature.
It was a unique paper. For the first time ever, a new form of extinct humans was described from DNA sequence data alone, in the total absence of any skeletal remains. Given that the mtDNA was so different from that of both modern humans and Neanderthals, we felt sure that we had found a new form of extinct human. In fact, we were so taken with this idea that, after some discussion, we decided to describe it as a new species, which we called
Homo altaiensis.

However, I felt vaguely uneasy about suggesting a new species and soon had second thoughts. To me, taxonomy, the classification of living organisms into species, genera, orders, and so on, is a sterile academic exercise, particularly when discussing extinct human forms. Whenever my students send me manuscripts in which they use Linnaean Latin names for groups that are commonly known—for example, “In order to better understand the pattern of genetic variation in
Pan troglodytes,
we sequenced . . . ”
—I always delete the Latin and sometimes even snidely ask who they are trying to impress by saying “
Pan troglodytes
” instead of “chimpanzees.” Another reason I dislike taxonomy is that it has a tendency to elicit scientific debates that have no resolution. For example, if researchers refer to Neanderthals as “
Homo neanderthalensis,
” they indicate that they regard them as a separate species, distinct from “
Homo sapiens.
” This invariably infuriates multiregionalists, who see continuity from Neanderthals to present-day Europeans. If researchers say, “
Homo sapiens neanderthalensis,
” they indicate that they see them as a subspecies, on par with “
Homo sapiens sapiens.
” This invariably infuriates proponents of the strict out-of-Africa hypothesis. These arguments I prefer to avoid, and although we had by now shown (but not yet published) that there had been mixing between Neanderthals and modern humans, I knew that taxonomic wars over Neanderthal classification would continue, since there is no definition of a species perfectly describing the case. Many would say that a species is a group of organisms that can produce fertile offspring with each other and cannot do so with members of other groups. From that perspective we had shown that Neanderthals and modern humans were the same species. However, this concept has its limitations. For example, polar bears and grizzlies can (and occasionally do) produce fertile offspring with each other when they meet in the wild. Yet polar bears and grizzlies look and behave differently, and are adapted to different lifestyles and environments. It would seem rather arbitrary, if not outright ridiculous, to regard them as one and the same species. We didn’t know whether the fact that Neanderthals contributed perhaps 2 to 4 percent of the genes of many present-day humans meant that they were the same or different species. So it was ironic that, having always refrained from using a Latin name for Neanderthals in  our papers, I was now on the verge of introducing a new Linnaean species designation myself.

Despite my misgivings about fruitless taxonomic debates, I felt I had some reasons for this digression from my principles. The mtDNA of the Denisova individual was about twice as different from the mtDNAs of modern humans as was the mtDNA of Neanderthals. That probably made them more like
H. heidelbergensis,
who did get to have their own Latin species name. But there was also vanity involved. Not many people get to name a new hominin species, which made it tempting to do so, even more so because this was the first time it would be done based solely on DNA data. However, the deciding argument came both from some people in our group and from Henry Gee at
Nature.
He pointed out that if we didn’t take the initiative and give this hominin group a species name, someone else would. And that person might come up with a name we didn’t like. So, after deliberating with Anatoly and the team who had excavated the crucial finger bone, we settled on provisionally naming it
Homo altaiensis.

Nature
kept its promise to process our paper quickly: eleven days after our submission, we received comments from four anonymous reviewers. They all praised the technical aspects of the paper but they were divided on the issue of naming a new species. Two reviewers voiced concerns that we might actually have sequenced a late
Homo erectus.
They felt that if
H. erectus
had had continuous contact with groups in Africa, they may not show an mtDNA divergence as deep as their first exit out of Africa some 2 million years ago. I doubted this. But the fourth reviewer made the point that saved us from ourselves. He or she said that “once a name is in the taxonomic literature, it cannot be withdrawn later. So such provisional naming is not wise, I believe.” When I read this, I realized we had been foolish.

In the meantime, it dawned on us that the very large amounts of mtDNA that Johannes had been able to capture from the Denisova DNA libraries meant we would be able to sequence quite a bit of this individual’s nuclear genome. This would settle its relationships both to Neanderthals and to modern humans in a definitive way as well as its possible status as a new species. We rewrote the manuscript and removed any reference to a new species. Instead, we said that “nuclear DNA sequences are needed to clarify definitively the relationship of the Denisova individual to present-day humans and Neanderthals.” We sent it back to
Nature,
where it appeared in early April.
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As events would show, we had reason to be grateful that we had not named it a new species.