Wells: “Darwinism is Doomed” because we keep making progress

There are days when I simply cannot believe how dishonest the scoundrels at the Discovery Institute can be. This is one of them. I just read an essay by Jonathan Wells that is an appalling piece of anti-scientific propaganda, an extremely squirrely twisting of some science news. It’s called “Why Darwinism is doomed”, and trust me, if you read it, your opinion of Wells will drop another notch. And here you thought it was already in the gutter!

[Read more…]

Squid Hox genes

i-ccbc028bf567ec6e49f3b515a2c4c149-old_pharyngula.gif

i-cba1474d669ccfffe2c2d613f0545014-euprymna_icon.jpg

It’s April (not anymore—it’s September as I repost this), it’s Minnesota, and it’s snowing here (not yet, but soon enough). On days like this (who am I fooling? Every day!), my thoughts turn to spicy, garlicky delicacies and warm, sunny days on a lovely tropical reef—it’s a squiddy day, in other words, and I’ve got a double-dose of squidblogging on this Friday afternoon, with one article on the vampire squid, Vampyroteuthis infernalis, and this one, on squid evolution and cephalopod Hox genes.

[Read more…]

Evolution of alcohol synthesis

i-ccbc028bf567ec6e49f3b515a2c4c149-old_pharyngula.gif

We need to appreciate beer more. Alcohol has a long history in human affairs, and has been important in purifying and preserving food and drink, and in making our parties livelier. We owe it all to a tiny little microorganism, Saccharomyces cerevisiae, which converts complex plant sugars into smaller, simpler, more socially potent molecules of ethanol. This is a remarkable process that seems to be entirely to our benefit (it has even been argued that beer is proof of the existence of God*), but recent research has shown that the little buggers do it all entirely for their own selfish reasons, and they’ve been busily making alcohol that has gone undrunk by humankind for tens of millions of years.

[Read more…]

Cats, candy, and evolution

i-ccbc028bf567ec6e49f3b515a2c4c149-old_pharyngula.gif

Here’s a small taste of Roald Dahl’s Charlie and the Chocolate Factory, a sweet story about a poor boy and his visit to an amazing candy factory…you’ve probably heard of it, since the new movie is getting a lot of press.

Only once a year, on his birthday, did Charlie Bucket ever get to taste a bit of chocolate. The whole family saved up their money for that special occasion, and when the great day arrived, Charlie was always presented with one small chocolate bar to eat all by himself. And each time he received it, on those marvelous birthday mornings, he would place it carefully in a small wooden box that he owned, and treasure it as though it were a bar of solid gold; and for the next few days, he would allow himself only to look at it, but never to touch it. Then at last, when he could stand it no longer, he would peel back a tiny bit of the paper wrapping at one corner to expose a tiny bit of chocolate, and then he would take a tiny nibble—just enough to allow the lovely sweet taste to spread out slowly over his tongue. The next day, he would take another tiny nibble, and so on, and so on. And in this way, Charlie would make his ten-cent bar of birthday chocolate last him for more than a month.i-a420ae8c62e074dde7e2fce0652d306e-tinystop.gif

That’s how it is published, at any rate. What if it read something like this?

Only once a year, on his birthday, did Charlie Bucket ever get to taste a bit of chocolate. The whole family saved up their money for that special occasion, and when the great day arrived, Charlie was always presented with one small chocolate bar to eat all by himself. And each time he received it, on those marvelg ynfg, jura ur pbhyq fgnaq vg ab ybatri-a420ae8c62e074dde7e2fce0652d306e-tinystop.gif, ur jbhyq i-a420ae8c62e074dde7e2fce0652d306e-tinystop.gifrry onpx n gval ovg bs gur cncre jenccvat ng bar pbeare gb rkcbfr n gval ovg bs pubpbyngr, naq gura ur jbhyq gnxr n gval avooyr-whfg rabhtu gb nyybj gur ybiryl fjrrg gnfgr gb fcernq bhg fybjyl bire uvf gbathr. Gi-a420ae8c62e074dde7e2fce0652d306e-tinystop.gifr arkg qnl, ur i-a420ae8c62e074dde7e2fce0652d306e-tinystop.gifbhyq gnxr nabgure gval avooyr, naq fb ba, naq fb ba. Naq va guvf jnl, Puneyvr ji-a420ae8c62e074dde7e2fce0652d306e-tinystop.gifhyq znxr uvf gra-prag one bs oveguqnl pubpbyngr ynfg uvz sbe zber guna n zbagu.

[Read more…]

Hox cluster disintegration

i-ccbc028bf567ec6e49f3b515a2c4c149-old_pharyngula.gif

Hox genes are metazoan pattern forming genes—genes that are universally associated with defining the identities of regions of the body. There are multiple Hox genes present, and one of their unusual properties is that they are clustered and expressed colinearly. That is, they are found in ordered groups on the chromosome, and that the gene on one end is typically turned on first and expressed at the head end of the embryo, the next gene in order is turned on slightly later and expressed further back, and so on in sequence. That the tidy sequential order on the chromosome is associated with an equally tidy spatial and temporal pattern of expression in the body has always been one of the more fascinating aspects of these genes, and they are one of the few cases where we see an echo of phenotypic form comprehensibly laid out in the DNA.

[Read more…]

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.

i-e45e827a198c79097f0d6b1fbf5950ec-selam.jpg

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.

Rhabdomeric and ciliary eyes

i-ccbc028bf567ec6e49f3b515a2c4c149-old_pharyngula.gif

We are all familiar with the idea that there are strikingly different kinds of eyes in animals: insects have compound eyes with multiple facets, while we vertebrates have simple lens eyes. It seems like a simple evolutionary distinction, with arthropods exhibiting one pattern and vertebrates another, but the story isn’t as clean and simple as all that. Protostomes exhibit a variety of different kinds of eyes, leading to the suggestion that eyes have evolved independently many times; in addition, eyes differ in more than just their apparent organization, and there are some significant differences at the molecular level between our photoreceptors and arthropod photoreceptors. It’s all very confusing.

There has been some recent press (see also this press release from the EMBL) about research on a particular animal model, the polychaete marine worm, Platynereis dumerilii, that is resolving the confusion. The short answer is that there are fundamentally two different kinds of eyes based on the biology of the cell types, and our common bilaterian ancestor had both—and the diversity arose in elaborations on those two types.

[Read more…]

Patterning the nervous system with Bmp

I’m a little surprised at the convergence of interest in this news report of a conserved mechanism of organizing the nervous system—I’ve gotten a half-dozen requests to explain what it all means. Is there a rising consciousness about evo-devo issues? What’s caused the sudden focus on this one paper?

It doesn’t really matter, I suppose. It’s an interesting observation about how both arthropods and vertebrates seem to partition regions along the dorso-ventral axis of the nervous system using exactly the same set of molecules, a remarkable degree of similarity that supports the idea of a common origin. Gradients of a molecule called Bmp may be the primitive mechanism for establishing dorso-ventral polarity in animals.

[Read more…]