In the journal Science, a team headed by J. Craig Venter of the Institute for Genomic Research argues that the hardy organism and others like it make up what amounts to a third branch on the tree of life. Known as Archaea, for their ancient heritage, these microbes share traits with organisms in each of the two previously recognized biological ““domains’’ into which life has been divided according to its complexity. But an exhaustive mapping of Methanococcus’s genes turned up a twist. ““Two thirds of the genes are not things we’ve ever seen before,’’ says Venter.
That Archaea seem related to organisms in each of the other domains ““gives us hints that they may be precursors to all the life forms on the planet,’’ says Venter. Or perhaps on other planets. Since Archaea thrive under extreme conditions, they may live in places previously thought inhospitable. If there is life on Mars, it may look a lot like these odd Archaea.
