Resumen de Early bacteria had junkyard evolution
Lab tests involving microbes and a mammoth bone have shown that bacteria can passively soak up the genetic remains of long-dead organisms from the environment and add them to their own genomes. This ability is a previously ignored mechanism of evolution, says Soren Overballe-Petersen of the Natural History Museum of Denmark in Copenhagen. It joins sex, where two organisms combine their genes by mating; random DNA mutation; and the active transfer of genes between live microbes. By absorbing snippets of DNA that float in the environment, bacteria can access a junk shop of genetic material--some of which may no longer be in circulation in living things. What's more, the mechanism requires hardly any cellular machinery, suggesting it may be left over from the earliest forms of life. Long before the advent of sex, the first cells may have randomly scavenged stray bits of DNA to survive and evolve.
