Nick Matzke at PT describes a poster waved in protest at the recent Darwin vs. Design conference at Southern Methodist University. The poster read “Why do the ribosomes (protein synthesizing machinery) in our mitochondria match those of bacteria?Ã¢â‚¬Â The intent behind this question was to suggest that we evolved from bacterial ancestors, whose remnants in us are the mitochondria and, presumably, their ribosomes, which the poster asserts “match” those of bacteria.
Since I’m happy for the sake of argument to allow common descent, the more interesting question for me is what causal powers were required to produce ribosomes in the first place. But the poster, even taken on its own terms, is problematic. Eukaryotic, prokaryotic, and mitochondrial ribosomes are all quite different (see here), and it’s not clear whether mitoribosomes, as they’re called, are closer to prokaryotic than to eukaryotic ribosomes by any reasonable metric. In any case, to say that bacterial (prokaryotic) ribosomes “match” mitoribosomes seems false on any reasonable construal of the term.