Evidence is always the best way to resolve a debate

You know how we great clumsy gallumphing unsophisticated atheists are always comparing belief in gods to belief in fairies at the bottom of the garden or tooth fairies or whatever? We may have to revise those arguments.

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Now we really have to worry. If some space probe snaps a picture of an orbiting teapot, we’ll have nothin’.

Crap. Sean knocks the props out from under my godlessness. Now I’m going to have to convert to something…what does everyone recommend? Catholicism, LDS, Scientology, etc., or should I just go all the way primitive, erect a phallus-shaped rock in my backyard, and start worshipping that?

The Cambrian as an evolutionary exemplar

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I’ve been reading Valentine’s On the Origin of Phyla(amzn/b&n/abe/pwll) lately, and I have to tell you, it’s a hard slog. This is one of those extremely information-dense science texts that rather gracelessly hammers you with the data and difficult concepts on page after page. I am convinced that James W. Valentine is ten times smarter than I am and knows ten thousand times as much, and it’s a struggle to squeeze that volume of knowledge into my miniscule brain pan.

One thing I would like to greatly condense and simplify is his discussion of the Cambrian ‘explosion’. Misinterpretation of the Cambrian is one of the many prongs of the creationist assault on science; both old school Biblical creationists and the new stealth creationists of the ID movement have seized upon it as evidence of an abrupt creation—that a Designer poofed the precursors to all modern forms into existence suddenly, and without precursors, and that this observation contradicts evolutionary theory.

It doesn’t. Valentine has an excellent diagram that shows how wrong the creationists are.

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The sea urchin genome

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Oh happy day, the Sea Urchin Genome Project has reached fruition with the publication of the full sequence in last week’s issue of Science. This news has been all over the web, I know, so I’m late in getting my two cents in, but hey, I had a busy weekend, and and I had to spend a fair amount of time actually reading the papers. They didn’t just publish one mega-paper, but they had a whole section on Strongylocentrotus purpuratus, with a genomics mega-paper and articles on ecology and paleogenomics and the immune system and the transcriptome, and even a big poster of highlights of sea urchin research (but strangely, very little on echinoderm development). It was a good soaking in echinodermiana.

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A Devonian lamprey, Priscomyzon

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Reconstruction of Priscomyzon in dorsal (top) and left lateral (bottom) views. b, Macropthalmia stage of Lampetra showing anterior location of orbit and smaller oral disc, both positioned in front of the branchial region. The total length of the specimen is 116 mm. Drawings in a and b are scaled to show equivalent head lengths: from anterior limit of the oral disc to rear of the branchial region. Horizontal bars indicate the anterior–posterior span of the oral disc in each species.

The life of a parasite must be a good one, and often successful; the creature at the top of the drawing above is a primitive lamprey from the Devonian, 360 million years ago, and the similarities with the modern lamprey (at the bottom) are amazing. It’s less eel-like and more tadpole-like than modern forms, but it has the same disc-shaped mouth specialized for latching on to the flank of its host, it has similar circumoral teeth for rasping through scales and skin for its blood meal, the same pharyngeal adaptations for a life spent clamped to a fish.

I’ve put a photo of the fossil and a cladogram below the fold.

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Lucy is going on tour

The remains of Lucy, the famous fossil australopithecine, are going to be touring the US for the next few years. Start lining up. It’s opening in Houston.

The six-year tour will also go to Washington, New York, Denver and Chicago. Officials said six other U.S. cities may be on the tour. But they would not release the names, saying all the details had not yet been ironed out.

Minneapolis, maybe? I hope? Otherwise I’m going to have to make a trip to Chicago.

No word yet on whether the Answers in Genesis museum near Cincinnati will be bidding on the exhibit.

Dissecting embryos from half a billion years ago

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There is a treasure trove in China: the well-preserved phosphatized embryos of the Doushantuo formation, a sampling of the developmental events in ancient metazoans between 551 and 635 million years ago. These are splendid specimens that give us a peek at some awesomely fragile organisms, and modern technology helps by giving us new tools, like x-ray computed tomography (CT), scanning electron microscopy (SEM), thin-section petrography, synchrotron X-ray tomographic microscopy (SRXTM), and computer-aided visualization, that allow us to dig into the fine detail inside these delicate specimens and display and manipulate the data. A new paper in Science describes a survey of a large collection of these embryos, probed with these new techniques, and rendered for our viewing pleasure…that is, we’ve got pretty pictures!

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Gogonasus andrewsae

Here’s another tetrapodomorph fish to consternate the creationists. These Devonian/Carboniferous animals just keep popping up to fill in the gaps in the evolutionary history of the tetrapod transition to the land—the last one was Tiktaalik.

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Skull in lateral view.

This lovely beastie is more fish than frog, as you can tell—it was a marine fish, 384-380 million years old, from Australia, and it was beautifully preserved. Gogonasus is not a new species, but the extraction and analysis of a new specimen has caused its position in the evolutionary tree to be reevaluated.

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Cool data!

Nick Matzke has
compiled all the data on hominin cranial capacities into a single chart:

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I think I can see a pattern there, can you? He also has data on body size and brain size over there, take a gander at it. It looks like a simple and obvious example of evolutionary change in our lineage, I think.

Alas, it only shows specimens older than 10,000 years. I’m sure that right around 6,000 years ago, there was a sudden, dramatic change as the deity injected a soul into those crania.

Palaeos reborn!

First I reported that Palaeos was lost, and then that it might be found, but now it looks like we can safely say it is being reborn. The old version of Palaeos has been at least partially restored, but the really important news is that a Palaeos wiki has been set up and people are working on reassembling old content and creating new information in a much more flexible format. If you’ve got some phylogenetic or palaeontological expertise, you might want to consider joining the Palaeos team and helping out with this big project.

3.3 million years old, 3 years old

Say hello to Selam, or DIK-1-1, a new and very well preserved member of the family discovered in Dikika, Ethiopia. She belongs to the species Australopithicus afarensis and is being called Lucy’s little sister.

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She was only a toddler when she died about 3.3 million years ago, and from the teeth the authors estimate that she was about 3 years old. Most of the skeleton is intact, but doesn’t seem to have yet been fully extracted from the matrix.

Some of the surprises: the hyoid bone is chimpanzee-like, and implies chimp-like vocalization abilities. She had a long way to go before she could have a conversation. The fingers are long and curved, and the scapula is more gorilla-like than ours; there is a suggestion of better arboreal ability than we have.

Alemseged Z, Spoor F, Kimbel WH, Bobe R, Geraads D, Reed D, Wynn JG (2006) A juvenile early hominin skeleton from Dikika, Ethiopia. Nature 443:296-301.