“Universal common ancestry” with no “universal common ancestor”?
|May 30, 2017||Posted by News under Origin Of Life|
Earlier, we noted an interesting find: Archaea: Salt-loving methanogen found: They appear to have specialized in living off environments nothing else wants by using processes nothing else does. We will see stranger things yet, doubtless.
The archaea are very different from bacteria in the chemical makeup of their cell walls and in their DNA replication machinery. Indeed, some of the enzymes the archaea use to replicate DNA are similar to those used by eukaryotes. Woese concluded that the differences between archaea and bacteria, and between them and eukaryotes, were too great to be explained by descent from a universal common ancestor, as that term is normally understood.
Carl Woese proposed that there had been primitive cells (progenotes) that were “more or less a bag of semi-autonomous genetic elements” that were not organisms “in any conventional sense.”
But if our common ancestor with archaea and bacteria was not an organism, in what sense was it an ancestor? Why stop with a community of progenotes? Why not say our common ancestor was the primordial soup? Or the elements in the periodic table?
Life forms generally seek to remain in existence but elements in the periodic table do not. So there is the question of how or why these “bags” would seek to do so.
But here is where it gets interesting – the talkaround of the problem:
Yet evolutionary biologists—even those who share Woese’s view—continue to defend the idea of universal common ancestry. For example, W. Ford Doolittle wrote in 2009 that he doubts “there was ever a single universal common ancestor,” but “this does not mean that life lacks “‘universal common ancestry’” because “‘common ancestry’ doe not entail a ‘common ancestor.’” Why such mental gymnastics? Doolittle freely admits that it is because “much is at stake socio-politically,” namely the need to defeat “anti-evolutionists” in “the culture wars.”More.
Actually, Doolittle’s concept doesn’t sound like an idea at all. At best, it sounds like the primordial soup of an idea or the periodic table of the elements of an idea. Or maybe just a political slogan that stands in for an idea.
It becomes difficult to analyze the idea rationally at that point, which is doubtless an intended outcome.
The flight from analysis will ruin science.
See also: Mechanism for photosynthesis found in primeval, non-photosynthetic microbe
What we know and don’t know about the origin of life