Category Archives: Ancient DNA

What’s the Difference between a Neandertal and a Modern Human?

May 6, 2010

Bright and early yesterday morning, I was on the phone listening to a important piece of scientific history unfold. At the other end of the line was a Science magazine press conference in which researchers announced the world’s first draft sequence of the Neandertal genome. The team’s paper will appear tomorrow in Science.

I hadn’t had even my first cup of coffee yet, and my dog pawed at the office door, impatient to be fed and walked. But I was riveted by calm, sonorous voice of Svante Pääbo, a geneticist at the Max-Planck Institute for Evolutionary Anthropology and one of the team’s leading members, as he gave an overview of the project. “It’s extremely satisfying,” said Pääbo “that we now have the overview of the Neandertal genome after four years of intense efforts.” I can well imagine. Read more…

The Lords of Beringia

May 3, 2010

I am continually gob-smacked by the obsessive public interest in Atlantis. Why, oh why, does a mere mention of this fabled continent quicken the heartbeat of so many? Google, as I just did, “continent of Atlantis,” and you will turn up a whopping 1,020,000 hits. And a depressing number are devoted to bizarre lunatic-fringe theories concerning the location of the sunken continent (my current favorite puts Atlantis somewhere off the coast of the Indonesia).

By contrast, try mentioning Beringia to your friends and kids. How many of them have heard of it? It’s a real, honest-to-goodness sunken land–a huge chunk of northern real estate that once connected Alaska to Siberia and that now lies at the bottom of the Bering Sea. It drowned, as many of you undoubtedly know, when huge ice sheets melted at the end of the last Ice Age and topped up sea levels by some 330 feet. Read more…

Clothes Make the (Ancient) Man

April 25, 2010

“Good clothes,” wrote Thomas Fuller in 1732 in his book of proverbs, Gnomologia, “open all doors.” The British physician was almost certainly thinking of the importance of a spiffy tailcoat and breeches and a dressy lace shirt when trying to make friends among the wealthy and titled in 18th century England. But Fuller’s proverb could apply to early hominins as well: with the right clothing, our ancestors could survive winter cold and colonize increasingly hostile environments in Eurasia.

All this of course begs a question, or rather two. Who were the first clothes horses? And when did our mania for fashion begin? Archaeologists have never had much clear evidence to go on, for pieces of hide clothing or textiles tend to rot rapidly in the ground. But new research presented last week at the American Association of Physical Anthropologists sheds new light on the matter, by looking at an unlikely source of information: the human body louse. Read more…

Bronze-Age Europeans in China

March 18, 2010

Both the Grey Lady, the New York Times, and USA Today, have run stories (here and here) this week on the forthcoming exhibition of China’s famous Tarim Basin mummies and their gravegoods and possessions at the Bowers Museum in Santa Ana, California. The three mummies in the exhibit are European in appearance and date back as early as 4000 years, long before the opening of the Silk Road in the 2nd century B.C.

I have a very short interview with Victor Mair, a Sinologist at the University of Pennsylvania and the leading expert on these mummies, coming out in Science magazine later today. In addition, I have penned a feature article for Archaeology on Victor Mair and the latest research in the Tarim Basin, which will hit newstands in June.

But I will be attending the opening of the exhibition next weekend as a guest of honor, as the Bowers Museum has invited me to give a talk on mummies on Sunday, March 28th. So I will be posting here on my impressions on this major new exhibition. Chinese authorities have never before permitted any of the Tarim Basin mummies to travel outside Asia.

I should mention, however, that I have seen some of these mummies before. A decade ago, I joined Victor Mair and a geneticist colleague in Shanghai while they were trying to obtain permission to sample some of the mummies for DNA testing. At that time, I was fortunate enough to be taken down into a basement room at Shanghai’s Museum of Natural History, where one of the Tarim Basin mummies lay in a glass case. Later, I wrote a chapter in my book, The Mummy Congress, on the finds from the Tarim Basin.

These are extraordinary mummies. Their preservation is superb and they are daily revealing more about the lives of Bronze Age European migrants to Central Asia. I’ll have a lot more to say about this in a week’s time!

Photo by Wang da Gang

The Ancestral Journey of the Navajo

February 24, 2010

For years, anthropologists and archaeologists have puzzled over the origins of two famous aboriginal groups in the American Southwest: the Navajo and Apache people. The traditional languages spoken by the Navajo and the Apache differ strikingly from those of their neighbors, so much so that if you look at a linguistic map their homelands stand out like islands in a great sea.

But their languages are very closely related to the mother tongues of aboriginal people living in the subarctic in northwestern Canada and Alaska: indeed they belong to the same Athapaskan family. Moreover, linguists have long suggested that the ancestors of the Navajo and Apache people splintered off from their subarctic cousins roughly 1200 years ago. This begs a fascinating question. What might have prompted the ancestral Navajo and Apache to abandon their homeland in the northern forests and journey thousands of miles south to a very unfamiliar desert?

Some years ago, University of Alaska archaeologist William Workman proposed a possible answer. He suggested that the eruption of the White River volcano in southern Alaska around 1200 years ago could well have driven out both game and human hunters. Ash from the volcano blanketed a region of some 250,000 square kilometers: in some parts it reached 1.5 meters in thickness. All this, observed Workman, could well have forced the region’s Athapaskan speakers to search for a new homeland in the south.

Yesterday, a team led by Simon Fraser University researcher Tyler Kuhn shed new light on the dire nature of this eruption. In a new online paper in Molecular Ecology, Kuhn and his colleagues compared ancient DNA from caribou bones from the Yukon that dated before and after A. D. 1000. As the team discovered, the caribou living there before the White River eruption were genetically different from the caribou that resided there after.

In other words, a big change occurred in the local caribou population around the time of the White River eruption. The old herds vanished, and later new caribou herds moved in–quite likely as the land greened and grasses, sedges, willows and the like took hold once again.

All this strongly suggests that Athapaskan hunters in the area would have struggled to survive after the eruption. And indeed, archaeological evidence from the Yukon points to a major human transition as well. Before the eruption, the local hunters relied on throwing darts as their main weapon. After the ash fell, however, the inhabitants favored bow and arrows.

We are still a long way from definitive answers, but I’d say that it is looking more and more as if immense volcanic ash clouds, sunless days and a terrible famine changed the course of North American prehistory, pushing ancestors of the Navajo and the Apache peoples far to the south.

Exhuming Ancient Celebrities

February 17, 2010

I wasn’t planning to post today on Tutankhamun. Over the past twenty-four hours, journalists have spilled a cargo tanker’s worth of ink on news that the famous young king suffered from a host of serious ailments. I thought I would leave the story to the newspapers until I began browsing the coverage. Some reporters derided the Egyptian king as “malarial and inbred,” while others took lower aim. One online rag, for example, informed readers that “King Tut was a wreck, but his penis was ‘well-developed’.”

If you ask me, these exhumations and studies of ancient kings and other celebrities are becoming media circuses. All the high-tech poking and prodding quickly strips away the dignity and grandeur of great men and women, baring their physical frailties and secrets for all to see. In recent years, we’ve been subjected to several of these tawdry sideshows and I suspect there are more to come. I posted recently on the proposal to exhume Leonardo da Vinci. And two weeks ago, I spotted an article on a Danish team who will soon exhume a famous 17th century astronomer, Tycho Brahe.

None of the subjects, I might add, has given consent for such scientific study. And I sometimes wonder about the motives of the researchers. The scientists who propose to exhume Tycho Brahe, for example, want to determine whether the famous astonomer was murdered or whether he died of natural cause. This hardly seems reason enough to rifle through a tomb and disturb the sleep of the astonomer.

In future, I’d like to see researchers and reporters alike treat the ancient dead in the same way we treat the recently deceased–with respect and decorum. Few of us would consider prying open a recent grave and poring over newly buried remains just to satisfy a point of idle curiosity. So why is it ok to do that to a 17th century astronomer?

When I was writing my book, The Mummy Congress, I was really struck by the highly professional way that serious mummy researchers treated the ancient dead. They never made jokes at the expense of the dead or talked lightly or unfeelingly about their ailments. Indeed, during the examinations of the bodies, they often spoke as if the mummies themselves could hear exactly what was said.

Poor Tutankhamun. I’m glad he couldn’t hear what people were saying today.

Another Step Closer to Waking the Dead

February 11, 2010

This has been quite a week for ancient DNA stories. First, the feature article in Archaeology magazine about the possibility of Neanderthal cloning. And yesterday, a research paper in Nature reporting the success of an international team in reconstructing the ancient genome of a 4000-year-old man from northwestern Greenland.

The latter project clearly takes us one step closer towards the ability to clone a Neanderthal, the subject of my last two posts. But today, I’d to focus on the new research from Greenland and what I think is important about it.

The team, led by Eske Willerslev, a very, very media-savvy researcher at the University of Copenhagen (whose work I have posted on before), obtained its ancient DNA from a tuft of human hair excavated by an archaeological team in 1986 from a site in northwestern Greenland. Willerslev and his colleagues make a strong claim that they have ruled out modern contamination.

The archaeologist who excavated the hair has gone on record stating in the 87 pages of supplementary material posted by Nature that none of the ethnic Greenlanders on his team touched the sample. He also affirms that no one who was likely of Asian descent handled the hair later during its storage in the museum.

So the team does indeed seem to be working with an uncontaminated ancient sample. And Willerslev–an expert on ancient DNA–and his Ph.D. student Morten Rasmussen report that the team has reconstructed 80 percent of the nuclear genome. Based on this, the team has learned a number of things.

Number one, the hair belonged to a man who descended from northern-eastern Siberians who migrated to the New World as early as 6400 years ago. Number two, the individual in question had blood type A+, brown eyes, dark skin, a predisposition to baldness, a genetic adaptation to polar cold, and other identifiable traits.

Archaeologists already knew, however, from decades of painstaking study of artifacts that the early Greenlanders descended from northern Asian migrants. No surprises there. What is new, and I think very exciting, are all the details of appearance and physiology that have come to light about this particular individual– gleaned from just a few hairs.

Archaeology has never been very good at getting down to the level of the individual, particularly in that vast expanse of time we call prehistory. Excavations of house floors, middens, and shell mounds supply a lot of information on families, communities and populations. But they rarely say much if anything about individuals. And in places like North America, archaeologists try very hard now to avoid digging human remains–a major source of information about individuals–out of respect for Native American beliefs.

So this new ability to glean a lot of information about an individual from a human hair is bound to come in extremely handy, and I applaud the Danish team for their success. But its clear to me that such techniques are yet another worrying step along the road to cloning an ancient human or an ancient hominin.

The Danish led team is trying to calm our fears. “The genome we’ve reconstructed is no Frankstein’s monster,” team member Rasmussen told EurekAlert!. “It’s more like we’ve got the blueprints for a house, but we don’t know how to build it.”

For how long, I wonder. How long.

Reconstruction/drawing of Inuk by Nuka Godfredtsen.

Politics, Science and the Cloning of Neanderthals

February 9, 2010

As some of you will know, I posted yesterday on the ethics of cloning a Neanderthal, a subject I have been thinking about after reading an article Zach Zorich wrote for Archaeology magazine. Today Zach left a thoughtful response in the comments section of that post, raising a number of key points. I’d like to reply.

But first let me briefly summarize Zach’s remarks. He notes that all the researchers he interviewed for the piece are well aware of the ethical dilemmas of such cloning and that each had given serious thought to these matters–even though such clones are clearly somewhere off in the future.

Then Zach took exception to the comparison I made between the science of creating a Neanderthal clone and Stalin’s desire to fabricate an army of “humanzees”, human-chimpanzee hybrids. As Zach points out, “this isn’t some mad scientist’s scenario for world domination.” Cloning research, he points out, is part and parcel of a larger picture of legitimate medical research, and any heavy-handed legislation to prevent Neanderthal cloning could wreak havoc with projects designed to extend and protect human life.

I see Zach’s points here, and I share his concerns about heavy-handed legislation. I’d hate to see a law block an entire line of desperately needed medical research. But having said that, I still can’t shake off my anxiety about what could happen further down the road if and when science is indeed capable of cloning a Neanderthal.

Even well-meaning scientists, after all, are unable to foresee all the consequences of their research, as some have discovered to their rue. In the 1960s, for example, Norwegian researchers developed a new and very lucrative technology for ocean net-pen farming of Atlantic salmon. So great were the profit margins that a bedazzled Canadian government agreed to permit the same technology–with the same fish–on the British Columbia coast. Large corporations began farming Atlantic salmon in pens off the British Columbia coast in 1984, leading to the escape of tens of thousands of these alien fish into the Pacific Ocean. Today Atlantic salmon gobble up wild food and threaten native salmon species.

So even when guided by the best of all possible intentions, scientists can create futures they never envisioned. And it seems to me that when the stakes include the creation of another of our close human relatives that we need to exercise extra special care. I think that means taking into account worse -case scenarios, even one as dire as the intentional creation of Neanderthal clones by a malevolent political regime for the purpose of slave labor.

As Zach notes in his comments (and I should mention in the interests of full disclosure that I know Zach and that he is my editor at Archaeology), my worst-case scenarios do indeed draw on the research I did for my book on Hitler’s archaeologists. In fact, one of the things that struck me most forcibly during my four years of research and writing on the book was how terribly susceptible science is to political influence.

Most scientists need laboratories, expensive research equipment, and academic appointments in order to pursue their research. Corrupt regimes know this and they reward pliable scientists with prestigious jobs and ample research funds. Conversely, they weed out their opponents from universities and cut off their research funding. In Nazi Germany, these simple strategies convinced many scientists to pursue lines of state-approved racial research that they would probably have never considered otherwise. It could certainly happen again.

All this is to say I’m very uneasy with where this cloning research might lead us in the years to come. I’d like to see legislators at the UN draw a line in the sand. Cloning research for medical purposes is an important pursuit. I’m all in favor of it. But we should never allow cloning experiments to create Neanderthals.

Why We Should Worry about Neanderthal Clones

February 8, 2010

Should we clone Neanderthals? That’s the provocative question that science writer and editor Zach Zorich poses in the forthcoming issue of Archaeology, hitting the news stand on February 15th. I received an advance copy late last week and read Zorich’s article this weekend. I’ve been thinking about this question ever since, and already I have arrived at my own answer. No. No. NO.

First of all, I should point out that this is not a pie-in-the-sky question. Zorich interviewed an impressive A-list of researchers–including geneticists who are sequencing the Neanderthal genome and leading paleoanthropologists who study ancient hominins–and some clearly believe that a cloned Neanderthal awaits us somewhere down the line.

So it’s not too early to begin thinking and debating about the ethics of cloning one of our hominin kin. While some researchers champion the idea out of pure scientific curiosity and the desire to learn more about an extinct hominin, I think it’s a terrible idea. I simply don’t trust my fellow Homo sapiens sapiens to treat another hominin with kindness and respect. Our track record with other primates, for example, is appalling–using chimpanzees for circus shows and laboratory experimentation, hunting gorillas for meat, and killing orangutan mothers in order to sell their babies as pets.

And here’s something else that worries me about a Neanderthal clone. In the 1920s, the Soviet leader Josef Stalin ordered the researcher who perfected the technique of artificial insemination, Ilya Ivanov, to create a “living war machine. ” Ivanov’s brief, as American writer Charles Siebert reports in his remarkable book, The Wachula Woods Accord, was to artificially inseminate chimpanzees with human sperm to create a new hybrid.

Stalin dreamed of a large, invincible Red Army and a vast slave workforce to carry out his Five Year Plans. He thought a chimp-human hybrid would serve admirably. According to Russian newspapers, Stalin told Ivanov “I want a new invincible human being insensitive to pain, resistant and indifferent about the quality of food they eat.”

Ivanov failed miserably to produce such chimp-human hybrid, though he certainly tried. In 1930s, the biologist fell from political grace and was exiled to Kazakhstan in one of the many purges of the time.

All this strikes me as an important cautionary tale. What if one of the world’s dictators got it into his head to clone Neanderthals as slave laborers or a new kind of soldier, one physically stronger than modern humans? It sounds far fetched, I know. But I don’t think we can blithely ignore the lessons of history.