Conway Morris at Baylor

This is cool: Simon Conway Morris gave a talk at Baylor, and Cody was there. Conway Morris is a smart fellow who does some very interesting work, and now I learn that he’s also a charming speaker — even though I completely disagree with his conclusions, I wish he’d come a little farther north so I could listen to him. I’d most like to hear him talk about Cambrian and pre-Cambrian paleontology, but it sounds like he’s instead lecturing specifically on the ideas where he’s most wrong, his belief in the overwhelming power of natural selection (or perhaps, design) to drive convergence. Convergence happens, of course, but Conway Morris seems to favor sifting the evidence for similarities and ignoring the differences, and divergence happens, too.

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Simon Conway Morris and Life’s Solution: it’s tea.

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I’ve finished Simon Conway Morris’s Life’s Solution: Inevitable Humans in a Lonely Universe(amzn/b&n/abe/pwll), a book I’ve mentioned before and promised, with considerable misgivings, to read thoroughly. I didn’t like his ideas, I thought he’d expressed them poorly before, but I’d give his book on the subject a fair shake and see if he could persuade me.

My opinion: it’s dreck.

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Hagfish embryos!

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A hagfish egg with a 14.3-mm pharyngula-stage embryo inside (arrows). Scale bar, 5 mm.

I’ve been looking forward to seeing these little jewels in print since I saw Kuratani talk about them at the SICB meetings in January. Hagfish are wonderfully slimy jawless chordates that have been difficult to raise in the lab—although if you poke a whale corpse rotting in the cold deeps you’ll find them swarming everywhere. The Kuratani lab has managed to keep animals of the species Eptatretus burgeri alive and healthy in a lab aquarium maintained at cold temperatures (16°C), and has even had success in breeding them. That object to the right is a single hagfish egg, brown and leathery-shelled and surprisingly big—it’s an inch and a half long!

They collected 92 eggs, and then another limitation emerged: it took 5-7 months for embryos to develop in a small number of the eggs. Hagfish aren’t going to be your typical fast-developing model system, I’m afraid, but they are extraordinarily cool animals, and it’s good to see work beginning on them.

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Wells’ flagrantly false commentary on Hox complex structure

This evening, I am watching an episode of that marvelous and profane Western, Deadwood, as I type this; it is a most excellently compensatory distraction, allowing me to sublimate my urge to express myself in uncompromisingly vulgar terms on Pharyngula. This is an essential coping mechanism.

I have been reading Jonathan Wells again.

If you’re familiar with Wells and with Deadwood, you know what I mean. You’ll just have to imagine that I am Al Swearingen, the brutal bar-owner who uses obscenities as if they were lyric poetry, while Wells is E.B. Farnum, the unctuous rodent who earns the contempt of every man who meets him. That imagination will have to hold you, because I’m going to restrain myself a bit; I’m afraid Wells would earn every earthy sobriquet I could imagine, but I’ll confine myself to the facts. They’re enough. The man completely misrepresents the results of a paper and a whole discipline, and does it baldly on the web, as if he doesn’t care that his dishonesty and ignorance leave a greasy, reeking trail behind him.

Let’s start with Wells’ own words.

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Those disreputable evo-deviants and their bigotry against the single-celled

I must disagree with Larry Moran, who accuses the field of evo-devo of animal chauvinism — not that it isn’t more or less true that we do tend to focus on metazoans, but I disagree with an implication that this is a bad thing or that it is a barrier to respectability. Larry says we need to cover the other four kingdoms of life in greater breadth, which I agree is a fine idea. I would like to have a complete description of the genome of every species on earth, a thorough catalog of every epistatic interaction between those genes during development, a hundred labs working on each species, and a massive collection of papers for each one documenting every step and every protein and every variation in their development. I would like it tomorrow.

I think we all agree that that would be impractical. The question is how we will focus our research to maximize our use of limited resources, and get us useful answers that will lead us in productive directions. Larry is advocating maximizing our phyletic breadth by following organisms representative of the greatest amount of diversity. He is proposing this in opposition to the proposal from Jenner and Wills, who suggest a different strategy — and I find myself agreeing more with Jenner and Wills than with Moran.

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Don’t blame the dinosaurs

The mammalian tree is rooted deeply and branched early!

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(click for larger image)
All orders are labelled and major lineages are coloured as follows: black, Monotremata; orange, Marsupialia; blue, Afrotheria; yellow, Xenarthra; green, Laurasiatheria; and red, Euarchontoglires. Families that were reconstructed as non-monophyletic are represented multiple times and numbered accordingly. Branch lengths are proportional to time, with the K/T boundary indicated by a black, dashed circle. The scale indicates Myr.

That’s the message of a new paper in Nature that compiled sequence data from 4,510 mammalian species (out of 4,554) to assembly that lovely diagram above. Challenging the ‘conventional wisdom’ that mammalian diversity is the product of an opportunistic radiation of species after the dinosaurs were wiped out at the end of the Cretaceous 65 million years ago, the authors instead identified two broad periods of evolutionary expansion among the mammals: an early event 100-85 million years ago when the extant orders first appeared, and a radiation of modern families in the late Eocene/Miocene. A key point is that there is no change in rates of taxon formation across the Cretaceous/Tertiary (K/T) boundary—mammalian diversity was rich before the dinosaurs disappeared.

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