evolution
pharyngula | April 19, 2006It's a busy time for transitional fossil news—first they find a fishapod, and now we've got a Cretaceous snake with legs and a pelvis. One's in the process of gaining legs, the other is in the early stages of losing them.
Najash rionegrina was discovered in a terrestrial fossil deposit in Argentina, which is important in the ongoing debate about whether snakes evolved from marine or terrestrial ancestors. The specimen isn't entirely complete (but enough material is present to unambiguously identify it as a snake), consisting of a partial skull and a section of trunk. It has a sacrum! It has a…
pharyngula | April 19, 2006
Forbes magazine asks
What if you could pick one thing and start over from scratch? What would you change? Would you choose another career, a different home, a new spouse? Or would you choose to remake the world around you? Why not fix America's prison system, make schools more efficient, or make your political leaders more intelligent?
The editors asked me to contribute to their special report, speculating on how we would "reinvent things without regard for cost, politics or practicality". I thought a little bigger than a new spouse or career, though, and instead tossed in few peculiar…
oracknows | April 19, 2006I've been meaning to write about this topic for a long time.
In fact, ever since our illustrious Senate Majority Leader Bill Frist, who also happens to be a Harvard-educated cardiac surgeon, came out in favor of teaching "intelligent design" creationism alongside evolution in public school science classes back in August, I've been meaning to write a bit about a tendency that, as both a surgeon and a scientist, I find disturbing. That tendency is for physicians to be far more susceptible than one would think they should be to the siren call of the pseudoscience known as "intelligent design."…
pharyngula | April 18, 2006The relative length of bat forelimb digits has not changed in 50
million years. (a) Icaronycteris index, which is a 50-million-year-old bat fossil. (b) Extant adult
bat skeleton. The metacarpals (red arrows) of the first fossil bats are already
elongated and closely resemble modern bats. This observation is confirmed by
morphometric analysis of bat forelimb skeletal elements.
or•gan•ic | ôr'ganik | adjective. denoting a relation between elements of something such that they fit together harmoniously as necessary parts of a whole; characterized by continuous or natural development.
One of the…
evolgen | April 18, 2006Read this article. It deals with scientific literacy, politics, and religion in the United States, focusing on stem cells and evolution. Here's a taste:
To measure public acceptance of the concept of evolution, Miller has been asking adults if "human beings, as we know them, developed from earlier species of animals" since 1985. He and his colleagues purposefully avoid using the now politically charged word "evolution" in order to determine whether people accept the basics of evolutionary theory.
To find out what I think about rephrasing the question and substituting "develop" for "evolve…
grrlscientist | April 14, 2006After several of you asked me to make a wishlist, I did so. Shortly after that, one of you sent me a book from my wishlist that I've wanted for quite some time, Dinosaurs of the Air, by Gregory Paul (2002). I just received the book today and I want to thank you, Biosparite, for your kindness. As soon as I pulled it out of its packing, I showed this book to several of my colleagues, all of whom are very interested in it and they all thought the drawings are wonderful, too.
By the way, I am sorry for falling silent for so long. I have been overwhelmed these past few weeks with a paper and with…
evolgen | April 13, 2006William Harris came to my university to perpetuate misconceptions last September. I intended to write a summary of the experience, but I could never muster enough anti-venom to deal with his poison. In lieu of a formal treatment of Harris's bullshit, I've decided to (quite tardily) present a short description of what makes a discipline science. This is inspired by my inability get Harris to acknowledge that all scientific disciplines invoke observable causes to the events they attempt to explain. More after the jump.
I will refrain from comparing supernatural and naturalistic explanations…
evolgen | April 13, 2006I tend to blog in spurts. When I have nothing interesting to say (or lack the motivation to put together one of the 'BIG POSTS' I have waiting in the queue) I don't try to fill my blog with, well, filler posts. That's just the way I am. Inspiration tends to come in one big surge, at which point I'll write a bunch of entries in a matter of days. That's why this blog has laid dormant for nearly a week while the rest of the ScienceBlogs army trudges onward.
Despite what I said above, I felt a bit of an obligation to post something, regardless of how filler-esque it seems. So, I give you a…
pharyngula | April 12, 2006John Lynch beat me to this story about catfish feeding on land, so I'll be brief. It shows how the eel catfish, Channallabes apus, can manage to take an aquatic feeding structure and use it to capture terrestrial meals. Many fish rely on suction feeding: gape the mouth widely and drop the pharyngeal floor, and the resulting increase in volume of the oral cavity just sucks in whatever is in front of the animal. That doesn't work well at all in the air, of course—try putting your face a few inches in front of a hamburger, inhale abruptly, and see how close you come to sucking in your meal. So…
pharyngula | April 12, 2006A very cool idea: portray the Evolutionary Timeline on a web page, drawing it so that one pixel equals 30,000 years.
Go to the page and just keep scrolling and scrolling and scrolling…
loom | April 11, 2006Tomorrow I'll be on the radio show Science and Society at 4:20 PM EST. It's my second time on the show. Last time around we talked about the past six million years of hominid evolution (podcast here). This time we're hoping to cover just a bit more ground: the past 600 million years of vertebrate evolution. We'll try to hit on the big innovations that our ancestors acquired after we parted ways with the squishy beasts--such as brains, bones, a smart immune system, and hands and feet. You can listen live here, and the podcast should be available here shortly afterwards. is here. (Scroll down…
jlynch | April 10, 2006A just-published paper in PLoS Biology has thrown some light on the relationship between placental mammals. The authors used retroposed elements, and by scanning more than 160,000 chromosomal loci and selecting from only phylogenetically informative retroposons, they recovered 28 clear, independent monophyly markers that they feel conclusively verify the earliest divergences in placental mammalian evolution.
Below the fold, I provide a copy of their derived phylogeny, but a few things are worth noting:
Eutheria are divided into Xenarthra, Afrotheria & Boreotheria, with the Xenarthra -…
jlynch | April 10, 2006One of the annoying things about being on the (relatively) west coast is that those to the east usually get first dibs on anything that appears. So, while PZ has posted this already, I'm going to go ahead and do it anyways.
It's been a busy week or two here, and will be getting busier. I have three honors theses to shepherd as well as the usual teaching and service responsibilities.
loom | April 9, 2006On Thursday I wrote about a new paper reporting the reconstruction of a 450-million year old hormone receptor, and experiments indicating how it evolved into two receptors found in living vertebrates such as ourselves.
On Friday I took a look at the initial response to the paper from intelligent design advocates at the Discovery Insitute. They claim that there exist biological systems that show "irreducible complexity," which could not possibly have evolved. In response to the new research, intelligent design advocates claimed that hormones and their receptors do not actually make the cut as…
grrlscientist | April 8, 2006
More commentary on Tiktaalik roseae, this time from the Wichita Eagle (click image and you will be magically transported there). Do be sure to read the little sign on the lower left side, too.
Update: this morning on National Public Radio's show, Wait, Wait, Don't Tell Me! they asked this;
Question: Why would fish want to leave the water?
Answer: Because fish schools were teaching creationism!
Thanks, Ian!
tags: evolution, Tiktaalik rosea, fish, cartoon, humor
pharyngula | April 7, 2006
The tetrapod isn't surprising…you know you're a science nerd when the first thing you wonder is what the flowering plants are doing in the Devonian. It also makes me wonder just how old Bob the Angry Flower is.
loom | April 7, 2006Yesterday I blogged about a new study in which scientists reconstructed 450 million year old proteins in order to trace the evolution of some receptors for hormones. The paper itself does not comment on the implications these results have for intelligent design, which claims that some biological systems are too complex to have evolved. But in the accompanying commentary, Chris Adami does. (Adami is the brains behind Avida, an artificial life program that I wrote about in Discover in 2005.) He writes,
Although these authors have not directly addressed this controversy in the discussion of…
loom | April 6, 2006Over the last few years, scientists have figured out how to recreate biological molecules that were last seen on Earth hundreds of millions of years ago. Until now, scientists have reconstructed ancient proteins to gather clues about life was like long ago. But now some scientists at the University of Oregon have done something new with these old proteins: they used them to figure out how evolution produces complex systems--exactly the sort of systems that creationists would have us believe cannot evolve.
Scientists reconstruct an ancestral protein by tracing its evolution into new versions…
loom | April 6, 2006Mark Siddall, the leech hunter, is on another quest. He's posting updated from his journeys through Australia in search of new leeches. Read them at Blood Lust II.
pharyngula | April 5, 2006My 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…