![]() Though he spent much of his career in Germany, he is Swedish. The traces are still there, with modern Europeans having 1-2% of Neanderthal DNA and some people in Asia and Australasia as much as 6% of Denisovan DNA.ĭr Paabo’s career is, then, a tour de force of scientific detection. More relevant from a present-day perspective is that both also interbred with Homo sapiens when that African species began turning up in their European and Asiatic homelands 70,000 years or so ago. ![]() Denisovans were related more closely to Neanderthals than to Homo sapiens, and subsequent analysis has shown that the two sometimes interbred. The original genome of this species was extracted from a finger bone found in a cave in the Altai mountains of Russia. The biggest surprise of Dr Paabo’s career, though, was probably the identification, purely from its DNA, of an entire, new species, Homo denisova. And within that catalogue, presumably, lies the explanation, not yet elucidated, of what makes Homo sapiens such an extraordinary species. That, together with successor sequences, has permitted the compilation of a catalogue of genes found in Homo sapiens but not Homo neanderthalensis. The real prize, however, came in 2009, when he and his colleagues at the Max Planck Institute for Evolutionary Anthropology, in Leipzig, Germany, which he helped to found, announced a sequence of the nuclear DNA of Neanderthals-for technological improvements meant that the definition of “detectable quantities” had by then changed. This provided, through estimates based on how quickly such DNA evolves, an estimate (800,000 years ago) of when the two species diverged. And because there are lots of them in a cell, whereas there is only one nucleus, their DNA is much more abundant, and therefore more likely to survive in detectable quantities.ĭr Paabo’s analysis showed that Neanderthal mitochondrial DNA is indeed different from that of Homo sapiens. Because they derive from bacteria that became symbiotic about 2bn years ago with cells ancestral to animals, plants and so on, mitochondria have their own DNA, separate from that in a cell’s nucleus. A cell’s mitochondria are its power packs, extracting energy from glucose and transferring it to a molecule called ATP, which then drives metabolic reactions. ![]() His first big breakthrough came in 1997, when he sequenced mitochondrial DNA from Neanderthals, a human species that lived in Europe and western Asia, and became extinct about 30,000 years ago. But gradually, as genetic-sequencing techniques improved, he was able to push his work backward in time. ![]() Mummification in Egypt began about 4,600 years ago-the blink of an eye in palaeontological terms-and the desert climate of that country is particularly conducive to the preservation of DNA. ![]() His early work, starting in 1985, was on Egyptian mummies. In particular, Dr Paabo concentrated on ancient members of the genus Homo. Palaeogenomics is the study of the genomes of ancient, often extinct, biological species. ![]()
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