Although, actually, Darwin is literally dead

The Second Edition of the Darwin is Dead carnival is up. I think we can declare that the “Darwin is Dead carnival” is dead now. Orac seems to have had a little problem tallying up the entries, but out of 7 links:

  • Three are satires of ID and creationism.
  • One is a press release from the Discovery Institute.
  • One is more PR from the Institute for Creation Research.
  • One is PR from Answers in Genesis.
  • Precisely one is an actual blog entry from a sincere creationist (who, by the way, thinks “irreducible complexity” is a serious problem for molecular biology, and therefore has demonstrated that he is a clueless goombah), and even that one the carnival host had to go trawling through crap and invite him to submit it.

I’m sorry to say that the selection is pathetic. Try comparing this thing to the Tangled Bank (which has a new edition coming up next week, by the way)—creationists have another reason to be embarrassed.

Christian pigs at the trough…with Hovind’s snout up front

Christian corruption at its finest: here’s a Florida Republican working to give a money-making park a tax exemption.

A biblical theme park in Orlando where guests pay $30 admission to munch on “Goliath” burgers and explore reproductions of 2000-year-old tombs and temples could get a property tax exemption written into state law.

A Senate committee easily passed a bill that would grant theme parks “used to exhibit, illustrate, and interpret biblical manuscripts … ” an exemption from local property taxes, like churches, even though the parks charge money.

[Read more…]

Malacology morning

My wife thought this story about left-handed snails having a competitive advantage, in that they seem to be better able to escape predation by right-handed crabs, was pretty cool. She also recalled that I’d scribbled up something about snail handedness before, so to jump on the bandwagon, I’ve brought those stories over from the old site.

The handedness of snail shells is a consequence of early spiral cleavages in the blastula. It’s a classic old story in developmental biology—everyone ought to know it!

There was also a story last year about shell chirality in Euhadra. There, it wasn’t a matter of predation, but a potential isolating mechanism, and one where mating compatibility and character displacement could play a role.

Everyone can read up on snails while I’m off at class this morning.

Chirality in Euhadra

i-ccbc028bf567ec6e49f3b515a2c4c149-old_pharyngula.gif

Since Coturnix turned me on to this paper on snail chirality in PLoS (pdf), I had to sit down and learn something new this afternoon.

Chirality is a fascinating aspect of bilaterian morphology. We have characteristic asymmetries—differences between the left and right sides of our bodies—that are prescribed by genetic factors. Snails are particularly interesting examples because snail shells have an obvious handedness, with either a left-(sinistral) or right-handed (dextral) twist, and that handedness derives from the arrangement of cell divisions very early in development.

[Read more…]

Spiral cleavage

i-ccbc028bf567ec6e49f3b515a2c4c149-old_pharyngula.gif

Developmental biologists are acutely interested in asymmetries in development: they are visible cues to some underlying regional differences. For instance, we’d like to know the molecules and interactions involved in taking a seemingly featureless sphere, the egg, and specifying one side to go on to form a head, and the the opposite side to form a tail. We’d like to understand why our back (or dorsal) side looks different from our belly (or ventral) side. One particularly intriguing distinction, though, is the left-right axis. For the most part, left and right are nearly identical, mirror-images of one another, but there are also key asymmetries. Your heart, for instance, is larger on the left side than the right, your liver lies mostly on the right side of your abdomen while the stomach arcs to the left, and these arrangements are essential for normal function. Left-right asymmetries are more subtle than anterior-posterior or dorsal-ventral differences, and that makes them especially fascinating.

[Read more…]

Tiktaalik makes another gap

Paleontologists have uncovered yet another specimen in the lineage leading to modern tetrapods, creating more gaps that will need to be filled. It’s a Sisyphean job, working as an evolutionist.

i-b0b25d35216973e6b76df2f5ed9e177d-tiktaalik.jpg

This creature is called Tiktaalik roseae, and it was discovered in a project that was specifically launched to find a predicted intermediate form between a distinctly fish-like organism, Panderichthys, and the distinctly tetrapod-like organisms, Acanthostega and Ichthyostega. From the review article by Ahlberg and Clack, we get this summary of Tiktaalik‘s importance:

First, it demonstrates the predictive capacity of palaeontology. The Nunavut field project had the express aim of finding an intermediate between Panderichthys and tetrapods, by searching in sediments from the most probable environment (rivers) and time (early Late Devonian). Second, Tiktaalik adds enormously to our understanding of the fish-tetrapod transition because of its position on the tree and the combination of characters it displays.

[Read more…]