The book. On February 17, the review Nature published a study describing the remains of three mammoths and the analysis of the DNA which had been preserved there despite the passage of time: a new record was established, the specimen baptized Krestovka, found in Siberia, having been dated more than 1.5 million years ago. That is double the oldest fossil whose genome has been deciphered so far, a horse from the Yukon (Canada) 700,000 years old.
These spectacular results are the fruit of a scientific revolution that Ludovic Orlando talentedly retraces, in Fossil DNA, a time machine. Today research director at the CNRS, at the head of the Toulouse anthropology and genomics center (Paul-Sabatier University), he is one of the pioneers of paleogenomics, this “multidiscipline” which combines molecular biology, mathematics, computer science and archeology. He knows all the players, who are often competitors, and all the constraints: the sequencing of the 2.8 billion bases of the genome of TC21, his Canadian horse, took him three years of patient and uncertain work.
Better understand epidemics
But the outlook is breathtaking. DNA is an unparalleled key to accessing ancient worlds. It is this molecule, however fragile, that allowed us to determine that our cousinhood with Neanderthals had gone as far as interbreeding. It was she who revealed the existence of another humanity, the Denisovans, with whom our ancestors also cohabited. Even more strongly, in the absence of fossils, the DNA trapped in the sediments betrays the passage of animals or “homo”. Ludovic Orlando even began to reveal how the environment could influence the expression of the genome, without changing it – the first to characterize an ancient epigenome.
In addition to our own lineage, the genetic time machine helps us better understand major epidemics, the way in which the microbes that inhabit us have evolved, the phenomena of domestication, animal and plant, of extinction… Such an explanatory power could lead to hubris, to the temptation to annex the entire field of studies on lost worlds.
Nothing like it with Ludovic Orlando, who pleads for a closer collaboration with archaeologists or linguists and warns against certain interpretations which would litter their knowledge. Another salient point of his book is the attention paid to what these discoveries tell us about human migrations, the impermanence of peoples, and interbreeding. This reflection on the strictly political dimension of such work is to be welcomed.
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