Comments on: The Perfect Bird Family Tree…

By: Greg Laden

Greg Laden — Fri, 27 Jun 2008 16:37:47 +0000

We will perhaps swap Gould-Dershowitz stories….. I’ve got only one but it is fun.

By: Rick MacPherson

Rick MacPherson — Fri, 27 Jun 2008 16:34:31 +0000

fair enough, greg…i also didn’t mean to suggest sanctifying the man… he was a real prick at times…but i did also see him (in academic settings during graduate seminars) show some real hubris… with the late great jack sepkoski, with the late great robert nozick, with the not so late and not so great alan dershowitz, and with the amazing andy knoll…

By: Greg Laden

Greg Laden — Fri, 27 Jun 2008 16:13:37 +0000

Your last point is exactly right (well, the rest is too, but I want to focus on that) … It could be said that in retrospect, evolution is totally predictable but actually predicting into the future is somewhat more difficult….There is another part of this, tough, that I’ve alluded to above only parenthetically. The degree to which evolutionary ‘history’ is inevitable could put force behind any form of the teleological argument. Personally, I think that Gould over-emphasized contingency as non-predictability for that reason in his popular writings (which was most of his writings by count).Besides, I like giving him a hard time. I only knew him a little, interacted a few times, but I never once (over several years with the occasional chance) saw him give another human being credit for having a thought that he (gould) might learn from. For that level of rudeness, I chose to not sanctify him. There must have been some people he did not treat like intellectual dirt (maybe his students?). (I’m speaking here only in academic settings. In more social settings he was a party monkey, of course).

By: Rick MacPherson

Rick MacPherson — Fri, 27 Jun 2008 15:19:36 +0000

greg…i’m not gonna toss you to the dogs on this one… i don’t know boo about bird phylogeny, but i am going to add some thoughts on how steve gould’s characterized…considering australia’s marsupial fauna alone, it’s easy to see evidence for your argument… in the absence of placental mammals, evolution filled ecological guilds with what was available… and it certainly plays out in marine reef communities where isolated atolls in the indo-pacific are little species factories, churning-out fascinating ecological players to fill available niches… but there’s the hard and soft version of contingency that steve sold… he was percolating various versions into his essays years before codifying it in “wonderful life”… if i’m reading the versions correctly, steve freely admits that there were limits to hardcore contingency and at some point along the history of life, oak trees, hippos, petunias, and homos sapiens were likely (if not inevitable)… get enough morphology and proteins already coded and certain trends play out over time…but i don’t think steve, in the very end, was even defending an empirical argument for contingency as a macroevolutionary process so much as he was defending his “view of life” heavily flavored by cultural and literary extrapolation… his entire epilog to “the structure of evolutionary theory” is nothing if not a final attempt to clarify this view… his analogy of a possible replay of life in a world where charles darwin was not born allows that natural selection and evolutionary theory would still develop and win acceptance in the scientific community…. his thought experiment of why should it matter if it were darwin, or wallace, or even great great great grandfather laden is more of an esthetic and philosophical point… his emotional rationale for why we care–the details, the sequence, the story–speaks more to the history and romance of science than the mechanics of evolutionary theory…i’d hate for steve’s legacy to be seen as some sort of lock-step, unyielding adherence to contingency at all costs…my own sense is i think what steve was really trying to accomplish with his “tape of life” metaphor was not so much hammer home the notion that our present is but one of many possible presents that COULD have happened… the important message i think he was trying to get across (at least in the story he told with the burgess shale fauna) was how could anyone standing on the shores of cambrian sea possibly PREDICT from the phyla scuttling about that we would end up with oak trees, hippos, petunias, and homos sapiens? if there’s anything the man muttered, it was that the history of life only makes sense in hindsight…

By: Greg Laden

Greg Laden — Fri, 27 Jun 2008 08:29:03 +0000

What have I missed?Uffda, Where do I begin?David, you are one of the smart people ruined by cladistics. I probably can’t fix that.A phylogeny is a tree-like structure modeling the evolutionary relationships among species or other taxonomic groups. There are many ways to do it, and Sibly and Alquist made phylogenies.A cladist is a person who addresses phylogeny through a very limited but useuful set of techniques, and who is often incapable of understanding complexity and ambiguity and would prefer that the rest of biology bend, however unnecessarily and uncomfortably, to the cladist’s dogma.On your point about virtually re-writing bird phjylogeny. Partly correct. I was originally going to segue into a critique of the hype that this new paper is getting because it is overblown. However, instead I decided to be nice and just made reference to the dust that will be flying. In fact, the phrase “virtually rewrite” does not have much meaning. I think I may go and make some adjustments to the text.Your response to my assertion regarding replaying history causes me to tell you to go read it again because I think you are telling me to say what I’m pretty sure I already said. But you are a pedant with a penchant for being vague, so there is probably something you are telling me that I’m not going to get or care too much about.The connection between the paper and the post? I can spell it out more clearly for you: Homoplasy should be rare if Gould is absolutely right. The more common it is, the sillier his assertion looks. An equally valid connection: I read something then I wrote something about it.

By: David Marjanovi?, OM

David Marjanovi?, OM — Fri, 27 Jun 2008 07:04:38 +0000

Sibley and A[h]lquist's DNA bird phylogeny

No, that was not a phylogeny. DNA-DNA hybridization is a phenetic method, not a phylogenetic one. It measures similarity instead of counting shared derived features; it doesn't even try to tell shared retained features apart from shared derived features and doesn't even try to distinguish shared ancestry from convergence.

and virtually re-write bird phylogeny?

It doesn't. It confirms many revolutionary findings of molecular analyses published in 2004 and 2006. (This includes swifts & hummingbirds being inside the nightjars & goatsuckers & oilbirds, flamingos and grebes being sister-groups and far apart from storks/herons and loons and cranes/rails, falcons and hawks & eagles being far apart, and much more.) It's just the first one with an impact factor over 3 or so.

I think that if you replayed the evolution movie again and again, starting with the Cambrian Explosion, you would get woodpeckers, humingbirds, and raptors again and again and again and again and again. You might not get birds every time, but you'd get these guilds. They may be in very different places on the phylogenetic tree, but these adaptive syndromes would be represented every time (and others, too, of course).

Even if so, they wouldn't necessarily be birds, let alone Neornithes. Think of the hummingbirds: the Old World hummingbirds died out in the Oligocene, and since then we've had nocturnal hummingbird-sized moths in that niche.And I don't see any connection between this point and the new paper. What have I missed?