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> If we accept evolutionary biology then a headline like this wouldn't be all that surprising.All living things converge at the root. That doesn't mean that ev

• Thrymr 8y ago
  > That doesn't mean that everything has already been "invented" at the root. Exactly. The "classical" view of evolutionary genetics is that new genes develop by mutation, are favored (or eliminated) by natural selection, and exchanged only within the same species by interbreeding. So the family tree of life is a map of how closely organisms are related, and they would share a gene only with the nearby branches of the tree descended since that gene arose. We have long known that the simple model is not complete, prokaryotes (bacteria and archaea) exchange lots of genetic material outside their own "species" (trickier to define for bacteria in any case), but it is becoming more widely recognized that lateral gene exchange happens a lot in all organisms. A recent popular book on the subject is "The Tangled Tree: A Radical New History of Life" by David Quammen.