development
pharyngula | January 4, 2011Morphological variation is important, it's interesting…and it's also common. It's one of my major scientific interests — I'm actually beginning a new research project this spring with a student and I doing some pilot experiments to evaluate variation in wild populations here in western Minnesota, so I'm even putting my research time where my mouth is in this case. There has been some wonderful prior work in this area: I'll just mention a paper by Shubin, Wake, and Crawford from 1995 that examined limb skeletal morphology in a population of newts, and found notable variation in the wrist…
pharyngula | December 27, 2010
When last we left this subject, I had pointed out that the phenomenon of embryonic similarity within a phylum was real, and that the creationists were in a state of dishonest denial, arguing with archaic interpretations while trying to pretend the observations were false. I also explained that constraints on morphology during development were complex, and that it was going to take something like a thorough comparative analysis of large sets of gene expression data in order to drill down into the mechanisms behind the phylotypic stage.
Guess what? The comparative analysis of large sets of…
pharyngula | December 11, 2010
This is awesome news. Biologists have figured out how to enable two male mice to have babies together, with no genetic contribution from a female mouse. I, for one, look forward to our future gay rodent overlords.
It was a clever piece of work. Getting progeny from two male parents has a couple of difficulties. One is that you need an oocyte, which is a large, specialized, complex cell type, and males don't make them. Not at all. You can tear a boy mouse to pieces looking for one, and you won't find a single example—they're a cell found exclusively in female ovaries.
Now you might think that…
pharyngula | November 22, 2010You all want to know what is going on in the minds of my students, right? Here you go.
Hannah writes about mitochondria, autism, and pain.
Lisa writes about autism, the dog genome, and sea urchins.
Logan writes about giant insects.
Kele has survived his senior seminar and is now writing about the genetics of Mario.
Rev. Frost is falling behind.
So is Anthony.
Gonza275 writes about treefrogs, the T allele, and developmental mathematics.
pharyngula | November 2, 2010My developmental class is still plugging away with some new entries.
Hannah writes about fetal alcohol syndrome and mosquito speciation.
Lisa writes about leopard camouflage and gene mapping.
Logan writes about hierarchical development in parasitic wasps and bicoid in flies.
Kele is still on hiatus. He's got a senior seminar on the Y chromosome coming up.
Rev. Frost writes about Trisomy 22.
Anthony and gonza275 need new material!
gregladen | October 22, 2010Human infants require more care than they should, if we form our expectations based on closely related species (apes, and more generally, Old World simian primates). It has been said that humans are born three months early. This is not accurate. It was thought that our body size predicted a 12 month gestation, and some suggested that Neanderthals would have had such, but this research conclusion has been set aside based on new analysis. But it is still true that developmentally, human children do not reach a stage of development that allows some degree of self care for a very long time…
gregladen | October 12, 2010Or, when the hunting season is closed, watch teh game (the guys), or when there are no sales, admire each other's shoes (the gals)?
This is, of course, a parody of the sociobiological, or in modern parlance, the "evolutionary psychology" argument linking behaviors that evolved in our species during the long slog known as The Pleistocene with today's behavior in the modern predator-free food-rich world. And, it is a very sound argument. If, by "sound" you mean "sounds good unless you listen really hard."
I list this argument among the falsehoods, but really, this is a category of argument…
pharyngula | October 4, 2010I would never have guessed this one. The Nobel Prize in Medicine has gone to Robert G. Edwards for his pioneering work in in vitro fertilization. It surprises me because it's almost ancient history — he is being rewarded for work done over 30 years ago. It's also very applied research — this was not work that greatly advanced our understanding of basic phenomena in biology, because IVF was already being done in animals. This was just the extension of a technique to one peculiar species, ours.
I don't begrudge him the award, though, because the other special property of his research was that…
pharyngula | September 28, 2010I told you I've got my development class blogging, and here's the update for this week.
Hannah's blog discusses recent observations in blind cavefish.
Lisa's Ledger is about a new Alzheimer-associated gene.
Development from a naiad is on a brief break while the author does some extracurricular traveling.
Kele's Science Blog goes above and beyond the call of duty to describe a classic paper on digit reduction in amphibian evo-devo.
Rev. Frost goes all neuro and describes experiments exploring cerebral palsy.
Weekly Developmental Biology Updates needs updating.
Developmental…
pharyngula | September 21, 2010I'm back to teaching developmental biology this term, and one of the things I do in my upper level classes is have students write blog entries on the themes of the course. In the past, I've given them space right here to do that, which I've found to be a parlous course of action — the commentariat here is savage and brutal, and infested with trollish nitwits who can derail threads spectacularly, so I'm doing it a little differently this time around. I've had them create their very own blogs on their own spaces, which has the additional benefit that maybe they can keep them going after they…
pharyngula | August 19, 2010A beekeeper did something simple: he put a bell jar over an opening in his beehive. The bees obliged by building a hive within it, where you could see it, and captured the process in a series of photos.
I'm fascinated by the fact that the first struts in the framework are regularly spaced vertical bars of wax — how did they do that? I want to see videos of those early stages when the bees are working to initiate the strips. I suspect there are some interesting bee:bee interactions going on as they set them up.
pharyngula | August 17, 2010There he goes again, making up nonsense and making ridiculous claims that have no relationship to reality. Ray Kurzweil must be able to spin out a good line of bafflegab, because he seems to have the tech media convinced that he's a genius, when he's actually just another Deepak Chopra for the computer science cognoscenti.
His latest claim is that we'll be able to reverse engineer the human brain within a decade. By reverse engineer, he means that we'll be able to write software that simulates all the functions of the human brain. He's not just speculating optimistically, though: he's…
pharyngula | August 12, 2010One of the subjects developmental biologists are interested in is the development of pattern. There are the obvious externally visible patterns — the stripes of a zebra, leopard spots, the ordered ranks of your teeth, etc., etc., etc. — and in fact, just about everything about most multicellular organisms is about pattern. Without it, you'd be an amorphous blob.
But there are also invisible patterns that you don't normally see that are aspects of the process of assembly, the little seams and welds where disparate pieces of the organism are stitched together during development. The best known…
pharyngula | August 3, 2010
This past weekend, I attended my 35th high school reunion. It's a strange phenomenon to be meeting people you haven't seen since you were 18, and further weirdness ensues when we discover that most of them are already grandparents. There have been a lot of life changes in 35 years. Saddest of all, though, is the ritual listing of the deceased…and I learned that one of my former classmates died in her late 40s of emphysema, a progressive and irreversible lung disease that leads to the near complete loss of lung function. The only cure right now is a lung transplant, and patients who've been…
pharyngula | July 22, 2010
I'm one of those dreadful animal-centric zoologically inclined biologists. Plants? What are those? Fungi? They're related to metazoans somehow. Lichens? Not even on the radar. The first step in fixing a problem, though, is recognizing that you have one. So I confess to you, O Readers, that my name is PZ, and I am a metazoaphile. But I can get better.
My path to opening up to wider horizons is to focus on what I find most interesting about animals, and that is that they are networks of cells driven by networks of genes that generate patterned responses of expression by cell signaling, or…
pharyngula | June 30, 2010Important clarification: CAH is a real and serious disease. There are no objections to pediatricians treating the physiological disorders in utero. However, lesbianism, traditionally masculine career choices, and disinterest in having children are not diseases…and the problem in this work is that the doctors involved clearly think they are, and are interested in using the drug dexamethasone to modify behavioral choices. That's the scary part.
Ladies, are you independent, stubborn, or mildly aggressive in your social interactions? Are you perhaps less interested in having sex with men than…
pharyngula | June 24, 2010I was mildly surprised at the reaction to this cool timelapse video of a molting crab — some people didn't understand how arthropods work. The only thing to do, of course, is to explain the molting process of insects and crustaceans, called ecdysis.
Let's go back to the basics first. In the beginning was the epithelium, a continuous sheet of linked cells that envelops multicellular organisms. These are living, dividing, dynamic cells that are flexible, can repair damage to themselves, and represent the boundary between the carefully maintained internal environment of the organism, and the…
pharyngula | May 9, 2010Years ago, when the Trophy Wife™ was a psychology grad student, she participated in research on what babies think. It was interesting stuff because it was methodologically tricky — they can't talk, they barely respond in comprehensible way to the world, but as it turns out you can get surprisingly consistent, robust results from techniques like tracking their gaze, observing how long they stare at something, or even the rate at which they suck on a pacifier (Maggie, on The Simpsons, is known to communicate quite a bit with simple pauses in sucking.)
There is a fascinating article in the NY…
pharyngula | April 27, 2010If you've ever invited me out to give a science talk, you know that what I generally talk about is this concept of deep homology: the discovery that features that we often consider the hallmarks of complex metazoan life often have at their core a network of genetic circuitry that was first pioneered in bacteria. What life has done is taken useful functional elements that were worked out in the teeming, diverse gene pools of the dominant single-celled forms of life on earth and repurposed it in novel ways. The really interesting big bang of life occurred long before the Cambrian, as organisms…
pharyngula | March 16, 2010
First, you start with a lizard.
Really, I'm not joking. Snakes didn't just appear out of nowhere, nor was there simply some massive cosmic zot of a mutation in some primordial legged ancestor that turned their progeny into slithery limbless serpents. One of the tougher lessons to get across to people is that evolution is not about abrupt transmutations of one form into another, but the gradual accumulation of many changes at the genetic level which are typically buffered and have minimal effects on the phenotype, only rarely expanding into a lineage with a marked difference in morphology.…