Nova science now. « Les humains sont apparentés aux virus » Clément Gilbert est chercheur au laboratoire Ecologie et Biologie des interactions (CNRS / université de Poitiers).
Avec Cédric Feschotte, professeur à l’université du Texas à Arlington, il a récemment publié un article dans Nature Reviews Genetics consacré aux virus endogènes, ces virus dont le génome est intégré pour tout ou partie dans le génome des espèces-hôtes (dont l'espèce humaine) et qui ouvrent une fascinante fenêtre sur l'évolution du monde viral. Des films comme Contagion ou des alertes médiatiques comme celle entourant la grippe aviaire ou la grippe A (H1N1) donnent au public la même image du virus pathogène et dangereux.
Pourtant l'image que s'en est faite la science n'est-elle pas bien différente de ce cliché ? En effet notre compréhension du monde des virus et de leurs interactions avec le reste du vivant a beaucoup évolué ces dernières années. Les virus sont non seulement très nombreux mais on sait désormais qu'ils présentent une très grande diversité génétique... Prehistoric Archaeology & Human Evolution. Robert Sapolsky: The uniqueness of humans. Svante Paabo: DNA clues to our inner neanderthal.
Pieces of the Human Evolutionary Puzzle: Who Was Australopithecus sediba? Courtesy of Steven Churchill, Duke University.
Few things remain as mysterious—or controversial—as our own history as a species. However, a series of papers released in Science may add another piece to the puzzle: Four papers draw back the curtain on Australopithecus sediba, announced earlier this year, detailing morphological features of the hand, foot, pelvis, and skull that may establish this species within the ancestral lineage of modern humans. In a subterranean cave at Malapa, South Africa, approximately 25 miles (40km) from Johannesburg, the remains of numerous hominins identified as Australopithecus sediba have lain between layers of flowstone—a type of rock that forms in caves, similar in composition to stalagmites and stalactites, except as the name implies, this rock forms in a layer that “flows” across the surface.
Flowstone is rich in uranium, which decays into lead. But what makes the fossils curious is their unique blend of traits. How Humans Became Social. Extinct Genome From Fossil Finger Posted Online. Tame Theory: Did Bonobos Domesticate Themselves? Time and again humans have domesticated wild animals, producing tame individuals with softer appearances and more docile temperaments, such as dogs and guinea pigs.
But a new study suggests that one of our primate cousins—the African ape known as the bonobo—did something similar without human involvement. It domesticated itself. Anthropologist Brian Hare of Duke University's Institute for Brain Sciences noticed that the bonobo looks like a domestic version of its closest living relative, the chimpanzee. The bonobo is less aggressive than the chimp, with a smaller skull and shorter canine teeth. And it spends more time playing and having sex. The similarities between bonobos and domesticated species dawned on Hare during a large departmental dinner, where he listened to Harvard University anthropologist Richard Wrangham hold forth on bonobos. The foxes that Hare mentioned were the legacy of Russian geneticist Dmitri Belyaev.
Both groups faced very different environments. Late Bloomers: "New" Genes May Have Played a Role in Human Brain Evolution. Billions of years ago, organic chemicals in the primordial soup somehow organized themselves into the first organisms.
A few years ago scientists found that something similar happens every once in awhile in the cells of all living things: bits of once-quiet stretches of DNA sometimes spontaneously assemble themselves into genes. Such "de novo" genes may go on to play significant roles in the evolution of individual organisms—even humans. But how many are there? More than anyone thought, it turns out. The most prolific source of new genes in animals, plants, fungi and other life whose cells have nuclei involves the shuffling or duplication of bits of DNA from existing genes. Human Ancestors Were Nearly All Vegetarians. New Fossils May Redraw Human Ancestry. Gains in DNA Are Speeding Research Into Human Origins. Earliest Homo Erectus Tools Found in Kenya.
Humans and Neanderthals had sex, but not very often. Tens of thousands of years ago, our ancestors spread across the world, having sex with Neanderthals, Denisovans and other groups of ancient humans as they went.
Today, our genes testify to these prehistoric liaisons. Last year, when the Neanderthal genome was finally sequenced, it emerged that everyone outside of African can trace 1 and 4 percent of their DNA from Neanderthals. The discovery was a vindication for some and a surprise to others. For decades, palaeontologists had fought over different visions of the rise of early humans. Some championed the “Out of Africa” model, which says that all of us descend from a small group of ancestors who came out of Africa, swept the world, and replaced every other group of early humans.
To an extent, these are caricatured versions of the two models, and there are subtler variants of each. Now, Mathias Currat from the University of Geneva and Laurent Excoffier from the University of Berne have weighed into the debate. Photo by Joe Dunckley.
Books. Homo sapiens - Who are we ?