development
pharyngula | August 21, 2011Jerry Coyne is mildly incensed — once again, there's a lot of
recent hype about epigenetics, and he doesn't believe it's at all revolutionary. Well, I've written about epigenetics before, I think it's an extremely important subject central to our understanding of development, and…I agree with him completely. It's important, we ought to spend more time discussing it in our classes, but it's all about the process of gene expression, not about radically changing our concepts of evolution. I like to argue that what multigenerational epigenetic effects do is blur out or modulate the effects of…
pharyngula | August 6, 2011I learned something new today, and something surprising. I've opened up my fair share of bellies and seen intestines doing their slow peristaltic dance in there, and I knew in an abstract way that guts were very long and had to coil to fit into the confined space of the abdominal cavity, but I'd always just assumed it was simply a random packing — that as the gut tube elongated, it slopped and slithered about and fit in whatever way it could. But no! I was reading this new paper today, and that's not the case at all: there is a generally predictable pattern of coiling in the developing gut,…
pharyngula | July 19, 2011The embryologists' way.
(Last edition of TET; Current totals: 12,751 entries with 1,439,596 comments.)
pharyngula | July 12, 2011That's not hyperbole. I really mean it. How else could I react when I open up the latest issue of Bioessays, and see this: Cephalopod origin and evolution: A congruent picture emerging from fossils, development and molecules. Just from the title alone, I'm immediately launched into my happy place: sitting on a rocky beach on the Pacific Northwest coast, enjoying the sea breeze while the my wife serves me a big platter of bacon, and the cannula in my hypothalamus slowly drips a potent cocktail of cocain and ecstasy direct into my pleasure centers…and there's pie for dessert. It's like the…
gregladen | July 7, 2011Behaviors are not caused by genes. There is not a gene that causes you to be good, or to be bad, or to be smart, or good at accounting, or to like bananas. There are, however, drives. "Drives" is a nicely vague term that we can all understand the meaning of. Thirst and hunger are drives we can all relate to. In fact, these drives are so basic, consistent and powerful that almost everyone has them, we share almost exact experiences in relation to them, and they can drive (as drives are wont to do) us to do extreme things when they are not met for long periods of time. While eating…
pharyngula | July 7, 2011I found a recent paper in Nature fascinating, but why is hard to describe — you need to understand a fair amount of general molecular biology and development to see what's interesting about it. So those of you who already do may be a little bored with this explanation, because I've got to build it up slowly and hope I don't lose everyone else along the way. Patience! If you're a real smartie-pants, just jump ahead and read the original paper in Nature.
A little general background.
Let's begin with an abstract map of a small piece of a strand of DNA. This is a region of fly DNA that encodes a…
pharyngula | June 28, 2011I tell other scientists all the time that their work is being appropriated by creationists who barely understand it, and that it is getting distorted to support bogus pseudoscience. Whenever you see a creationist quote a genuine science paper, you can pretty much trust that it is going to be mangled beyond recognition.
For instance, Jonathan MacLatchie raised a peculiar collection of questions to grill me with; here's one of them.
9) If, as is often claimed by Darwinists, the pharyngeal pouches and ridges are indeed accurately thought of as vestigial gill slits (thus demonstrating our shared…
pharyngula | June 25, 2011It's like talking to a brick wall: MacLatchie is appallingly obtuse. When last I argued with him, I pointed out that the major failing of his entire developmental argument against evolution was that it was built on a false premise. As I said then,
I can summarize it with one standard template: "Since Darwinian evolution predicts that development will conserve the evolutionary history of an organism, how do you account for feature X which doesn't fit that model?" To which I can simply reply, "Evolution does not predict that development will conserve the evolutionary history of an organism,…
pharyngula | June 18, 2011Launching from my discussion with Muslim wackjobs in Dublin, this video takes my casual conversation and fleshes it out with details and references. Hey, looks like I was right!
pharyngula | June 17, 2011Jonathan MacLatchie, the creationist who challenged me to answer his questions about development in Glasgow, has posted his account of our encounter and his problems with evolution. It is completely unsurprising — he still doesn't understand any of the points.
Of his 10 questions, 7 were quickly dismissable and were more than thoroughly addressed in my talk. They rest on a deep misconception that is shared with Jonathan Wells and many other pseudoscholarly creationists; I can summarize it with one standard template: "Since Darwinian evolution predicts that development will conserve the…
pharyngula | June 10, 2011Hey, it's on youtube already. There may be a few moments where I look a bit strained — that's because the video projector wasn't working well, and we actually had it sitting on the floor kind of crookedly aimed at the screen, and a helpful fellow was maneuvering it to make sure the part I was referring to was on the screen rather than the wall or the ceiling. But fortunately for you, those clever folks who produced the video spliced my slides directly into the video.
It's all about the real history of Haeckelian recapitulation and why evolution doesn't predict the crazy stupid things…
pharyngula | May 12, 2011Faces are weird. They really are largely accidents of development — all the fine features that we consider lovely sculpted signifiers of beauty are really just products of developmental processes, and what we recognize as pretty is actually just a good job of assembly. I've been talking about this bizarre way the human face is built for many years, especially since my interest in teratology means I spend a fair bit of time looking at cases where the assembly goes drastically wrong (in fish, not people; I can make things go wrong in fish embryos in ways that would send the mob after me with…
pharyngula | May 2, 2011I'm a major fan of kidneys — they're fascinating organs for discussion of both development and evolution. Today I lectured about them in my human physiology course, but I could only briefly touch on their development, and instead had to talk on and on about countercurrent multipliers and juxtamedulary nephrons and transport membranes and all that functional physiology stuff. So I thought I'd get the evo-devo out of my system with a few words about them here.
Our kidneys go through an elaborate series of three major developmental stages — we essentially build three pairs of kidneys as embryos…
pharyngula | April 28, 2011The last mission of the space shuttle will contain a student-initiated experiment: a collection of bobtail squid embryos will be launched into space. Which is cool, I suppose. I like squid, I like space, I like science, I like student research, let's just throw them all into one big tossed salad of extravagantly expensive tinkering.
So why am I so disappointed?
Because the experiment is so trivial and uninteresting. The squid Euprymna has a commensal relationship with the luminescent bacterium, Vibrio. Early in their development, special organs in the squid are colonized by the bacteria; the…
pharyngula | April 16, 2011Those of you who've been to a poster session at a science meeting know that they're noisy and chaotic and entirely reliant on interaction to work…so I'm not even going to try and describe it. Instead, I strong-armed Eric Röttinger into describing his poster on video for me, and here it is. He's describing his work on Kahikai, an online database for collecting information about the development of marine invertebrates.
pharyngula | April 10, 2011Paul Nelson has deigned to write a two-part essay on "Ontogenetic Depth", his sciencey made-up term for a metric that he claims makes evolution essentially impossible. We've been wrangling over this for a long time — he and Marcus Ross introduced this in a poster at the Developmental Biology meetings in 2004, titled "Understanding the Cambrian Explosion by Estimating Ontogenetic Depth", and in our conversation at that time I certainly got the impression that he and Ross were busy collecting this peculiar thing alien to creationists called "data". I have asked him multiple times over the last…
pharyngula | March 21, 2011
Clarifying tetrapod embryogenesis, accurately
By OldCola
[Note from pzm: The text of this one is a little rougher than I like, but the content is interesting and addresses the claims of a character who has been lurking about here for a while, and whose work I've criticized before. If nothing else, I'd also like to see a few science posts submitted as guest articles, so think of this as priming the pump.]
The article, "Clarifying tetrapod embryogenesis, a physicistʼs point of view," by V. Fleury, hasn't steered the revolution expected by Fleury in evo-devo. Two years after the publication,…
pharyngula | March 18, 2011That reputable scientist, Ann Coulter, recently wrote a genuinely irresponsible and dishonest column on radiation hormesis. She claims we shouldn't worry about the damaged Japanese reactors because they'll make the locals healthier!
With the terrible earthquake and resulting tsunami that have devastated Japan, the only good news is that anyone exposed to excess radiation from the nuclear power plants is now probably much less likely to get cancer.
This only seems counterintuitive because of media hysteria for the past 20 years trying to convince Americans that radiation at any dose is bad.…
pharyngula | March 15, 2011
About 600 million years ago, or a little more, there was a population of small wormlike creatures that were the forebears of all modern bilaterian animals. They were small, soft-bodied, and simple, not much more than a jellyfish in structure, and they lived by crawling sluglike over the soft muck of the sea bottom. We have no fossils of them, and no direct picture of their form, but we know a surprising amount about them because we can infer the nature of their genes.
These animals would have been the predecessors of flies and squid, cats and starfish, and what we can do is look at the genes…
pharyngula | January 5, 2011Among my usual flood of daily email, I frequently get tossed onto mailing lists for conservative think tanks. Why? I don't know. I suspect that it's for the same reason I also get a lot of gay porn in my email: not because I follow it or asked to be added, but because some tired d-bag with no imagination thinks its funny to dun me with more junk. The joke's on them, though: I might keep it around and skim the stuff now and then to get inspiration for a blog post, and then click-click — a few presses of a button and I add the source to my junk mail filter, and never see it again.
No, I didn't…