First Evolutionary Branching For Bilateral Animals

YOU want some science news from time to time? Okay, this is a press release from Brown University, which is still struggling to overcome the embarrassing fact that one of their graduates — a biology major — is Louisiana’s creationist governor Bobby Jindal.

Despite that unfortunate lapse, Brown is still a quality school, so we’ll give you some excerpts from Research Team Finds First Evolutionary Branching for Bilateral Animals, which appears on Brown’s public affairs website. The bold font was added by us:

When it comes to understanding a critical junction in animal evolution, some short, simple flatworms have been a real thorn in scientists’ sides. Specialists have jousted over the proper taxonomic placement of a group of worms called Acoelomorpha. This collection of worms, which comprises roughly 350 species, is part of a much larger group called bilateral animals, organisms that have symmetrical body forms, including humans, insects and worms. The question about acoelomorpha, was: Where do they fit in?

Well, where do Acoelomorpha fit in? Wikipedia’s entry hasn’t been updated to include the latest news from Brown. Their entry is brief, so we’ll copy what they say before it’s changed:

The Acoelomorpha are a disputed phylum of animals with planula-like features and formerly considered to belong to the phylum Platyhelminthes, but recently classified by Jaume Baguñà and Marta Riutort as a separate phylum, basal among the Bilateria.

The Acoela are very small flatworms that do not have a gut. Digestion is accomplished by means of a syncytium that forms a vacuole around ingested food. There are no epithelial cells lining the digestive vacuole. All other bilateral animals have a gut lined with epithelial cells. As a result, the acoels appear to be solid-bodied (a-coel, or no body cavity). Acoels are almost entirely marine, living between grains of sediment, swimming as plankton, or crawling on algae. Acoels have a statocyst, which presumably helps them orient to gravity.

Their soft bodies make them difficult to classify.

Okay, but things seem to have cleared up a bit. Let’s read from Brown’s press release:

To scientists, acoelomorpha, has been enigmatic, a “rogue animal,” said Casey Dunn, an evolutionary biologist at Brown University. “It has been wandering throughout the animal tree of life.”

It’s odd that the creationists haven’t pointed to this “mystery” worm as yet another “weakness” of evolution, but the likely reason is that they don’t know anything about biology, so it never occurred to them to mention it. We continue:

The worm wanders no more. Through a laborious genetic sequencing analysis, Dunn and an international team of scientists have settled the long-standing debate and determined that acoelomorpha belongs as a sister clade to other bilateral animals.

That’s nice, but why should we care? Here’s why:

The finding is significant, Dunn said, because it shows the worm is a product of the deepest split within the bilateral animals, the first evolutionary divergence within the group. Because of that, scientists have gained a key insight into the most recent common ancestor to bilaterians, a species that remains unknown.

Still unknown? Aha, a gap! That must be the point where the magic Designer diddled around to make us bilateral. Yes — this is powerful evidence of Intelligent Design! Don’t laugh, the creationists will make that claim. Here’s more from the press release:

The worm is “as distant as an animal can be in bilateria and still be a bilaterian,” said Dunn, assistant professor of biology. “So, now we have two perspectives to (find out about) this common ancestor, the acoelomorphs and all the other bilateral animals.”

There’s more information in the press release, so if this interests you, click over and check it out. They also give a link to the published research. This is the abstract in Proceedings of the Royal Society B: Assessing the root of bilaterian animals with scalable phylogenomic methods

In conclusion, before the creationists jump all over this, let your Curmudgeon be the first to say: “I ain’t no kin to no bilateral worm!”

Copyright © 2009. The Sensuous Curmudgeon. All rights reserved.

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4 responses to “First Evolutionary Branching For Bilateral Animals

  1. “…one of their graduates — a biology major — is Louisiana’s creationist governor Bobby Jindal.”

    Like the old adage says, “You can lead a horse to water but, you can’t make him drink.” Bobby was evidently smart enough to graduate from Brown but not smart enough to learn what his education meant.

  2. Before we accuse Jindal of the usual ignorance of evolution, let’s not forget (Discoveroid) Jonathan Wells, who all but admitted that he got his PhD specifically to better misrepresent evolution. He didn’t phrase it that way, of course, but the message was clear.

  3. Socrates doesn’t want to go to dinner with his friends, but his friends press him to go. He tells them he will merely talk them out of it; they know how persuasive he is. His friends reply that they will refuse to listen to him.

    There are any number of people who went to college, and learned about evolution, yet believe that it must mysteriously have ended in humans 20,000 years ago, and that minds are not limited by the bodies they are contained in, and that genetic inheritance has nothing to do with human abilities.

    These people are just as misguided as creationists, and far more influential.

  4. Gabriel Hanna says: “There are any number of people who went to college, and learned about evolution, yet believe that … that genetic inheritance has nothing to do with human abilities.”

    Yes! Lysenko was successful in producing a New Soviet Man for Stalin.