development
pharyngula | April 26, 2015
The latest fatuous obsession by Paul Nelson, Philosopher of Biology at the Discovery Institute, is a real corker. He has decided that nematodes could not possibly have evolved, because scientists (real ones, not creationist pseudoscientists) have produced an extremely detailed literature documenting their development; because Brenner, Horvitz, and Sulston (no creationists among them) won the Nobel Prize for their work describing the cell lineages to produce the worm; and because he doesn't understand developmental biology at all. I've got palm impressions in my forehead from smacking myself…
jhalper | February 12, 2015What's in a picture?
Prof. Benny Shilo knows the value of a good picture. We recently mentioned his book: Life’s Blueprint, which uses photographs of things like bread dough and yeast cells to illustrate the process of biological development. Here is the image from the most recent piece we have uploaded on his research:
This is an individual Islet of Langerhans, as you’ve never seen it before. The white dots are the insulin-containing vesicles inside the beta cells, which both sense glucose levels and secrete insulin. Shilo and his team managed to get “close-up shots” of the individual cell…
pharyngula | January 13, 2015I finally got around to finishing Greta Christina's Comforting Thoughts About Death That Have Nothing to Do with God. It's good! This book is the sort of thing atheism needs more of: an acknowledgment that the phenomena most important to human beings can be addressed effectively without imagining fantastic supernatural creatures. Atheists have this reputation of being nerds all wrapped up in abstract concepts and making arguments against the superstitious props that people claim to find useful in day-to-day life, and it's good that some of us make the effort to show that no, we do deal with…
pharyngula | October 21, 2014I have to admit that my first response to these reports out of Britain that stem cells had been successfully used to repair a complete spinal cord transection was skepticism -- incredulity even. They're reporting that a man with a completely severed spinal cord at level T10-T11 is able to walk again! The Guardian gushes! The Daily Mail gets in the act (always a bad sign)! When I read that the patient had an 8mm gap in his spinal cord that had been filling up with scar tissue for the last two years, I was even more doubtful: under the best of conditions, it was unlikely that you'd get…
pharyngula | August 28, 2014Sometimes, people email me with good questions. Here's one.
When I was a kid, my own visualization of evolution was Lamarckism.
But I didn't know it. In reading Dawkins and others, I know it doesn't exist. But it seems this article is claiming it does to some extent. Can you comment? I'm curious as to the current consensus as I've been reading a lot about genes that can be turned on and passed to offspring. Can you take a look?
This is a fairly common question. Looked at naively, developmental plasticity seems to be Lamarckian -- we're talking about organisms responding with…
pharyngula | August 20, 2014Susan Blackmore always lectures entertainingly -- really, if you get a chance to hear her, you should -- so I can guess how surprised she was when students claimed offense and walked out on her talk. They were religiously indoctrinated, and simply shut down their brains when the word "evolution" came up, and when she started presenting rational and secular explanations for the existence of religion, just forget it -- there were a lot of students who thought you could only quote the Bible and Koran with unstinting reverence, accepting their divine claims at face value.
It is sad to see young…
pharyngula | July 23, 2014 I think the engineers are just trying to wind me up, again. Joe Felsenstein tackles a paper published in an applied physics journal that redefines evolution and tries to claim that changes in aircraft design are a good model for evolution. It's a terrible premise, but also, the execution is awful.
But permit me a curmudgeonly point: This paper would have been rejected in any evolutionary biology journal. Most of its central citations to biological allometry are to 1980s papers on allometry that failed to take the the phylogeny of the organisms into account. The points plotted in those old…
pharyngula | July 7, 2014I've been following the story of stimulus-triggered acquisition of pluripotency (STAP) cells with considerable interest, and there's a good reason for that: from the very beginning, it contradicted how I'd always thought about cell states, and if it were true, I'd have to rethink a lot of things, which was vexing. But on the other hand, empirical results always trump mental models, so if the results held up, there was no question but that I'd have to go through that uncomfortable process of reorganizing my preconceptions. It would be OK, though, because there'd be a great prize at the end.…
dr. dolittle | June 24, 2014 Image of C. elegans from http://www.easternct.edu/~adams/C.eleganslanding.html
New research published in PLOS Genetics shows that starving C. elegans (Caenorhabditis elegans) during the late larval stage of development when the worms are undergoing tissue growth and formation halts cellular activity at previously unknown checkpoints in their development. These findings show that nutrition is an important cue to signal whether or not the worms should continue on to the next stage of development. Interestingly, the two-week starvation period actually doubled the lifespan of the worms as they…
dr. dolittle | June 3, 2014 Image of a zebrafish larva from (NHGRI Press Photos).
Calcium is very important for the normal development, growth and survival of most vertebrates. Therefore, regulation of calcium intake and disposal is well-controlled. Mammals obtain most of their calcium from the diet, whereas fish obtain calcium by absorbing it from the external environment. For adults, this occurs in the gills and for larvae it is absorbed through the skin. What this means is that fish living in low calcium environments can acclimate by increasing the absorption of calcium from the water.
Dr. Kwong (Dept. of Biology…
pharyngula | March 11, 2014I was talking about sex and nothing but sex all last week in genetics, which is far less titillating than it sounds. My focus was entirely on operational genetics, that is, how autosomal inheritance vs inheritance of factors on sex chromosomes differ, and I only hinted at how sex is not inherited as a simple mendelian trait, as we're always tempted to assume, but is actually the product of a whole elaborate chain of epistatic interactions. I'm always tempted in this class to go full-blown rabid developmental geneticist on them and do nothing but talk about interactions between genes, but I…
gregladen | February 28, 2014John Abraham has an interesting post up at the guardian called "Global warming action: good or bad for the poor?" It is a response to a post by a group of guys who tend to write annoying stuff about climate change (you can go to John's post for that information). Here, I want to make a brief comment related to John's excellent post.
The crux of John Abraham's post is this, in two parts: 1) Some have argued that mitigation against climate change is bad for "the poor" (read: people in developing countries) because they have a right to go through the same phases of technological and social…
pharyngula | December 27, 2013What does it take to get Carl Zimmer to review your research in the New York Times?
I suppose it helps to be at Harvard. It also helps to have a combination of subjects — evolution and the human brain — that Zimmer has written about in the past. It helps to have a paper with lots of very pretty diagrams — the authors' hypothesis is professionally illustrated. It's also a good idea to have a vast sweeping explanation for the exceptionalism of the human brain. In this case, they call it the Tethering Hypothesis, and it's supposed to explain how humans evolved all these remarkable cognitive…
pharyngula | December 7, 2013Razib Khan poked me on twitter yesterday on the topic of David Dobbs' controversial article, which I've already discussed (I liked it). I'm in the minority here; Jerry Coyne has two rebuttals, and Richard Dawkins himself has replied. There has also been a lot of pushback in the comments here. I think they all miss the mark, and represent an attempt to shoehorn everything into an established, successful research program, without acknowledging any of the inadequacies of genetic reductionism.
Before I continue, let's get one thing clear: I am saying that understanding genes is fundamental,…
pharyngula | December 3, 2013The one thing you must read today is David Dobbs' Die, Selfish Gene, Die. It's good to see genetic accommodation getting more attention, but I'm already seeing pushback from people who don't quite get the concept, and think it's some kind of Lamarckian heresy.
It's maybe a bit much to ask that the gene-centric view of evolution die; it's still useful. By comparison, for instance, it's a bit like Mendel and modern genetics (I'll avoid the overworked comparison of Newton and Einstein.) You need to understand simple Mendelian genetics — it gives you a foundation in the logic of inheritance, and…
pharyngula | October 26, 2013I'm going to tell you about a paper that was brought to my attention by some poor science journalism, so first I have to complain about the article in the Guardian. Bear with me.
This is dreadfully misleading.
Though everybody's face is unique, the actual differences are relatively subtle. What distinguishes us is the exact size and position of things like the nose, forehead or lips. Scientists know that our DNA contains instructions on how to build our faces, but until now they have not known exactly how it accomplishes this.
Nope, we still don't know. What he's discussing is a paper that…
pharyngula | August 29, 2013While we've been waiting and waiting for the physicists to get their act together and deliver on Mr Fusion home energy sources and flying cars, the biologists have been making great progress on the kinds of things that turn biologists on. The latest development: growing tiny little human brains in a bucket. Only let's not call them brains…they are cerebral organoids. Hugo Gernsback would be so proud.
Here's the latest development. Start with embryonic human stem cells, or induced pluripotent stem cells (cells which you've reset to a kind of embryonic state by using a virus to transfect them…
pharyngula | July 2, 2013I know you're thinking we've had more than enough discussion of one simplistic umbrella hypothesis for the origin of unique human traits — the aquatic ape hypothesis — and it's cruel of me to introduce another, but who knows, maybe the proponents of each will collide and mutually annihilate each other, and then we'll all be happy. Besides, this new idea is hilarious. I'm calling it the MFAP hypothesis of human origins, which the original author probably wouldn't care for (for reasons that will become clear in a moment), but I think it's very accurate.
A list of traits distinguishing humans…
jhalper | May 27, 2013To attain knowledge, add things every day. To attain wisdom, remove things every day.
Lao Tsu
Apparently our nervous systems develop according to the Chinese philosopher’s principle of being and not being. As our nerve cells grow, they send out long extensions – axons – throughout the developing tissues. And as they reach out, some are also pruned back. The configuration of nerve endings we finally possess depends on both what was added and what was removed.
Which axons will complete their developmental journeys and which will be pruned back? For some, it is simply a matter of fate.
But in…
pharyngula | April 29, 2013After our disastrous chick lab — it turns out that getting fertilized chicken eggs shipped to remote Morris, Minnesota during a blizzard is a formula for generating dead embryos — the final developmental biology lab for the semester is an easy one. I lectured the students on structuralism and how there are more to cells then genes (there's also cytoplasm and membranes and environment) earlier today. This afternnon I've given them recipes for soap bubble solution and told them to play. They're supposedly making little model multicellular organisms by chaining soap bubbles together, and…