evolution
pharyngula | April 5, 2006
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.
Sinistral (left)…
grrlscientist | April 5, 2006
One of three newly-discovered specimens of the 383 million-year-old
Tiktaalik roseae.
These specimens fill a gap in the fossil record between aquatic and terrestrial animals.
Image: Ted Daeschler.
Making that transition from aquatic life to living on land was very important for vertebrates. However, there has been a gap in the fossil record at precisely that transitional point -- up until now, that is. Today, a group of scientists report that they found a group of three fossils from "crocodile-like" animals that neatly fit into the evolutionary progression as animals moved from water to…
pharyngula | April 5, 2006Paleontologists 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.
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…
loom | April 5, 2006Tiktaalik: music to my ears.
Tiktaalik is the lilting name of a newly discovered fossil fish with fingers. It lived 380 million years ago in the northern reaches of Canada, back when the northern reaches of Canada were tropical coastal wetlands not far from the equator. Tiktaalik's discoverers (Ted Daeschler, Neil Shubin, and Farish Jenkins) detailed their discovery in back-to-back papers in today's issue of Nature. In some ways Tiktaalik is big news. It may prove to be the single most important fossil for telling us how our ancestors changed from fish to land vertebrates complete with legs,…
pharyngula | April 3, 2006There are these fossilized embryos from the Ediacaran, approximately 570 million years ago, that have been uncovered in the Doushantuo formation in China. I've mentioned them before, and as you can see below, they are genuinely spectacular.
Parapandorina raphospissa
But, you know, I work with comparable fresh embryos all the time, and I can tell you that they are incredibly fragile—it's easy to damage them and watch them pop (that's a 2.3MB Quicktime movie), and dead embryos die and decay with amazing speed, minutes to hours. Dead cells release enzymes that trigger a process called autolysis…
stcynic | April 3, 2006Carl Zimmer has a terrific blog post on the subject of endogenous retroviruses (ERVs) that should be mandatory reading for anyone who still denies common descent. ERVs are viruses that get inserted into the genomes of other organisms and are inherited by the descendants of that organism. He writes:
Scientists can identify viruses lurking in our genome (known as endogenous retroviruses) by their distinctive DNA. A fully-functioning retrovirus sequence contains three genes--one for copying DNA, one for a shell, and one for escaping and invading cells. These genes are flanked by a series of…
stcynic | April 3, 2006From an article in a Kentucky newspaper:
To William Dembski, all the debate in this country over evolution won't matter in a decade.
By then, he says, the theory of evolution put forth by Charles Darwin 150 years ago will be dead.
The mathematician turned Darwin critic says there is much to be learned about how life evolved on this planet. And he thinks the model of evolution accepted by the scientific community won't be able to supply the answers.
"I see this all disintegrating very quickly," he said.
This is not his first attempt at playing prophet. His last prediction, over which he…
grrlscientist | April 3, 2006According to an opinion poll from late 2004, only 13% of all Americans think that humans evolved without any guidance from an all-powerful divine being. In view of this surprising lack of knowledge, I think it is essential that the public is presented with more details about evolution, and this is exactly what this book strives to accomplish. To celebrate the 200th anniversary of Charles Darwin's birth on 12 February 2009, Niles Eldredge, curator of the American Museum of Natural History, designed a wonderful traveling exhibition that documents and discusses the development of Darwin's…
pharyngula | April 1, 2006Some fields of science are so wide open, such virgin swamps of unexplored territory, that it takes some radically divergent approaches to make any headway. There will always be opinionated, strong-minded investigators who charge in deeply and narrowly, committed to their pet theories, and there will also be others who consolidate information and try to synthesize the variety of approaches taken. There are dead ends and areas of solid progress, and there is much flailing about until the promising leads are discovered.
Origins of life research is such an unsettled frontier. I wouldn't want to…
oracknows | April 1, 2006You know, after all these years as a scientist, physician, and skeptic, I've been wondering. Perhaps it's time to undergo a reassessment of my and philosophy. I've always been a bit of a curmudgeon, and it hasn't really gotten me anywhere. My words appear to have no impact on the credulous.
For example, perhaps I've been a bit harder than I should be on purveyors of dubious alternative medicine. Millions of people use it every day. Would they use it if there weren't anything to it? I think not. After all, look at all those testimonials for chelation therapy, Reiki therapy, Chinese energy…
loom | March 31, 2006A couple weeks ago I wrote about the 98,000 viruses that have permanently pasted their genes into our genome over the past 60 million years. What makes these viruses doubly fascinating is that scientists are making new discoveries about them all the time. Over at the open-access journal PLOS Pathogens, two new papers add some pieces to the puzzle of how these viruses get into our genomes, and how they affect our health along the way.
The first paper offers a striking portrait of a virus hopping species. Researchers at the Cleveland Clinic stumbled across the virus as they were studying…
oracknows | March 30, 2006Earlier this week, I wrote about how the principles of population evolution can be applied to premalignant lesions in order to predict which lesions would progress to cancer. This time around, I'd like to discuss how using evolutionary principles can provide insights to human disease that would not be as obvious or that would take much longer to discover without considering evolution. One of the beautiful things about evolution and applying it to medicine is that one can find connections in unexpected places that may actually shed light on the pathogenesis of human diseases and even suggest…
pharyngula | March 28, 2006
A while back, I criticized this poorly implemented idea from Paul Nelson of the Discovery Institute, a thing that he claimed was a measure of organismal complexity called Ontogenetic Depth. I was not impressed. The short summary of my complaints:
Unworkable idea: There was no explanation about how we could implement and test the idea, and despite promises at the time, Nelson still hasn't produced his methods.
False assertions and confusing examples: He claims that all changes in early lineages are destructive, for instance, which is false.
Bad metaphors: He uses a terribly flawed metaphor…
jstemwedel | March 28, 2006You'll recall that the Lancaster(California) school district has recently adopted a "science philosophy" that calls for critical thinking about evolutionary theory ... but no other scientific theory in the curriculum.
You'll recall that the school district trustees didn't seem to view this as having anything to do with opening the door for the teaching of creationism or intelligent design.
If you read the comments, though, you've discovered that Alex Branning, the entrepreneur who spearheaded this new policy, and who claimed to have no truck with creationists or ID proponents, is the…
oracknows | March 28, 2006Duck, everyone!
Matt (a.k.a. The Pooflinger) has found a PDF file containing a brand new FAQ about Kansas's new science standards, the ones that purport to "teach the controversy" about evolution. While I'm on a roll about evolution (and, yes, the next installment of my Medicine and Evolution series should come by the end of the week, Monday at the latest), I thought I'd mention this. Naturally, seeing what a target-rich environment the FAQ is, the Pooflinger can't resist proceeding to do what The Pooflinger does best: Flinging poo at the FAQ, giving it a great fisking.
A brief excerpt:
From…
oracknows | March 28, 2006Via Red State Rabble, I've become aware of an incredibly depressing story about science teachers in Arkansas explicitly censoring themselves when it comes to teaching evolution (the "e-word," as they call it) or in geology class teaching that the earth is 4.5 billion years old:
Teachers at his facility are forbidden to use the "e-word" (evolution) with the kids. They are permitted to use the word "adaptation" but only to refer to a current characteristic of an organism, not as a product of evolutionary change via natural selection. They cannot even use the term "natural selection." Bob…
razib | March 27, 2006Interesting report out, Evolutionary biology research techniques predict cancer. Medicine has been around for thousands of years, from the "healings" of shamans to the "theoretical" paradigm of Galen. It seems possible that until the last 100 years or so medical techniques were just as likely (or more likely in many situations) to exacerbate illnesses as they were to help. The medical arts might be an outgrowth of our psychological biases, not materialist considerations (an analogy with financial "analysts" might be appropriate). Purely empirical sciences focused on proximate aspects of…
jstemwedel | March 26, 2006Hey, guess what? A California school district has adopted a new science policy aimed at getting students to think more critically ... about evolutionary theory. It is not entirely clear whether members of the Lancaster School District board of trustees recognize that the policy effectively singles out evolution for scrutiny, or whether they were duped. But I'm pretty sure I've heard this song before.
Here's the coverage from the Antelope Valley Press:
LANCASTER - The Lancaster School District board of trustees voted to implement a "philosophy" of science instruction that encourages…
jlynch | March 26, 2006Jonathan Wells wrote a paper a while back that proposed a "ID-derived" explanation for cancer. I've written about that before (here, here , here, here, and here) as have others. Thus, this is of interest:
In a study published online today in Nature Genetics, Carlo Maley, Ph.D., a researcher at The Wistar Institute, and his colleagues report that precancerous tumors containing a population of highly diverse cells were more likely to evolve into cancer than those containing genetically similar cells. The finding suggests that, in at least some forms of cancer, the more genetically diverse a…
razib | March 24, 2006About a month ago I asked around for some bio-geek-rhymes. MC Coffee Mug, AKA The Genius, stepped forward. Props to the thug (and PUBMED too).
Matako-chan, represent!
MC Coffee Mug rap
yo I'm down for chuck d like
Thomas Huxley
where my bulldogs at this shit
is getting ugly
punk please styles are various
and sundry
found the game like amerie in jamaica wanting
leapt in cos cats wasn't really hungry
break ya off a fireball like chun li
gave ya girl a dose of oxytocin in her undies
trust me fundies do not want to test
I got bullets in my power point
I'll put'em in a chest
tryna get in my head…