Henry Gee relishes the memoir of Svante Pääbo, a leader in the field of ancient DNA.
Neanderthal Man: In Search of Lost Genomes
- Svante Pääbo
At a Royal Society meeting in London last year, just weeks before the publication in these pages of a high-quality Neanderthal genome (K. Prüfer et al. Nature 505, 43–49; 2014), David Reich — one of the paper's authors — spoke of “introgression” between Neanderthals, Homo sapiens and other hominins. This irked a member of the audience. “Are you telling me,” he asked, in cut-glass tones, “that these different species copulated with one another?” I was seized by an impulse to stand up and reply, in similarly stentorian fashion, “Not only did they copulate, but their union was blessed with issue!” (I stayed in my seat.)
The study of human origins and evolution currently stands on a cusp. For decades we have had to make do with bones and stones, thin gruel from which to craft a narrative. Now we can extract DNA from fossils. Not just in bits and pieces, each as enigmatic as a broken tooth or a chipped stone flake — but entire genomes. Unlike fossils, genomes can tell stories. They can legitimately link species into skeins of common ancestry and descent.
If there is one name associated with ancient DNA, it is Svante Pääbo. Now at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, Pääbo pioneered and has largely led the field for the past three decades. His book, Neanderthal Man, is perfectly timed, beautifully written and required reading — it is a window onto the genesis of a whole new way of thinking. (I should add a disclaimer at this point. I have a walk-on part in Neanderthal Man. Pääbo is as disarmingly candid about journals and editors as he is about anything else. I get off lightly.)
“You feel you should have Neanderthal Man on the bench as you try its techniques for yourself.”
The book is primarily a memoir. Pääbo recounts his life story with a Fennoscandian frankness that some readers might find disconcerting. Along the way, he tells us a great deal about science and scientists. There is mercifully little of the didactic treatment of the structure of DNA and genes that authors feel obliged to rehearse on such occasions. Dispensing quickly with such banal necessities, Pääbo gets on with the cutting-edge science to which he was witness, and in some cases helped to create — the astonishing development of devices that could be used to sequence DNA ever more efficiently and at lower and lower cost. He describes the technology clearly, almost like a recipe book: you feel you should have Neanderthal Man on the bench as you try its techniques for yourself.
Thanks to these developments, scientists are finding many more species of extinct hominin lurking out there in the shadows, betrayed by no known fossil evidence. For example, Denisovans, extinct hominins that lived in Siberia until relatively recent times, are much better known from their DNA than from the tally of their fossils — a small, nondescript finger bone and a peculiar tooth. And yet in their DNA are traces of yet another unknown species — glimpsed only as stretches of nucleotides — as evanescent as the smile of the Cheshire Cat.
Pääbo illustrates how the advent of ancient DNA has already had a profound effect on our understanding of human evolution. Skulls and skeletons, once put away in cupboards lest they frighten the undergraduates, are being brought out into the light. Some of these peculiar specimens — such as the skull from Iwo Eleru in Nigeria that looks archaic but is only 13,000 years old — may represent evidence of a richer and much more diverse prehuman history than we are used to thinking about. It has taken the recovery of ancient DNA, not more fossil bones, to jolt us into this wider reality, to force our gaze over a great, unexplored new world.
But as Pääbo recounts, there have been many false positives along the way. He deals harsh judgement on some of the grand claims from the Wild-West phase of ancient DNA research, before secure protocols had been established (and no, we at Nature don't escape his searchlight glare). And he does not spare himself from criticism. He looks back on the beginnings of his career in the 1980s, when, torn between a fascination for Egyptology and biochemistry, he mixed the two and tried to extract DNA from an Egyptian mummy. He thought he was making history. What he made was a mess. But, like all true scientists, he never gave up, finding all sorts of ways to achieve his goals, inventing new techniques and new ways of seeing. Eventually, in 1985, he reported the successful cloning of DNA from a mummy, and history was made.
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