There’s been some developments this day.
First of all a defunct blog on history and philosophy of science has revived with a new skin and as a group blog: AmericanScience: A Team Blog. I keep wanting to say “F&*k yeah!” It used to be the Forum for the History of Science in America. Some nice pieces there already (but horrible horrible font choices: I say this as a quandam graphic artist and compositor, okay?)
Second we have, courtesy of Softpedia (which turns out to be a useful science news feed) some developments in systematics and phylogeny. Or perhaps I should say, some phylogeny FAIL.
The first one is that – as the headline screams – ‘Mosaic of Life’ May Replace ‘Tree of Life’ - why? because it turns out genes cross taxonomic boundaries. Which we knew already. Gene trees are not species trees, and it is a category error to think that they should be the same. In fact, in order to identify lateral transfer of genes, we already need to have a species tree, or (to be consistent with my prior arguments) a relationship statement of taxa, which turn out to be something you can represent as a tree. This is on a par with the awful New Scientist article from a while back.
The second one is that a cricket Species Found Unchanged After 100 Million Years - except that the species are not the same, only the whole group, which is only the same if you ignore changes at the species level. The genus has remained the “same” for values of the “same” that include species evolution. And “genus” is an artificial construct at any rate, defined largely by traits that do not change much. Hence, the title of the press release should have read: “Things which do not change much by definition haven’t changed much, if you squint”.
Finally Bjørn Østman at Pleiotropy points out problems with a recent reassignment of Acoels (arsehole lackers) from a basal node on the evolutionary tree to a within-deuterosome node. The problem? Deuterosomes have arseholes, so this guy, which everybody wanted to be a kind of surrogate for the common ancestor of all bilaterans, is in fact a vastly reduced version of us. But…
They used microRNAs as their character set. They ignored, in other words, morphology and development, the traditional criteria for inferring relationships, in favour of a single test criterion. And this is because RNA is a “magic molecule”.
But there’s even a problem with Bjørn’s objection: why should we think that the morphology and development of these guys should be placed at the base anyway? The answer is simple: it makes evolutionary sense. No-arseholes come before arseholes, right? Well now this is an interesting question. How do we know that? Are we using hypotheses as evidence here? Why can’t a group be greatly reduced, evolutionarily? Even Darwin noted this among his barnacles. The presumption of what Hennig called transformation series is not supported by direct evidence, and so wanting these guys to fall anywhere in an evolutionary tree is fraught, although not, I think, beyond overcoming. It’s just that we had better be testing things as closely to the evidence as we can, and not rely on “what everybody knows”, or as J. B. S. Haldane called it, Aunt Jobisca’s Theorem.
<end of rant>