development
pharyngula | March 6, 2010Freeman Dyson (with whom I have many disagreements, so don't take this as an unqualified endorsement), wrote an interesting article that predicted, in part, a coming new age of biology. I think he's entirely right in that, and that we can expect amazing information and changes in this next century.
If the dominant science in the new Age of Wonder is biology, then the dominant art form should be the design of genomes to create new varieties of animals and plants. This art form, using the new biotechnology creatively to enhance the ancient skills of plant and animal breeders, is still…
pharyngula | February 23, 2010People who don't understand modern evolutionary theory shouldn't be writing books criticizing evolutionary theory. That sounds like rather pedestrian and obvious advice, but it's astonishing how often it's ignored — the entire creationist book publishing industry demands a steady supply of completely clueless authors who think their revulsion at the implications of Darwinian processes is sufficient to compensate for their ignorance. And now Jerry Fodor and Massimo Piattelli-Palmarini, a philosopher and a cognitive scientist, step up to the plate with their contribution to this genre of…
pharyngula | December 30, 2009Here's another of Casey Dunn's Creature Casts, this time on shifting color spots in marine snails.
CreatureCast - Flamingo Tongue Snails from Casey Dunn on Vimeo.
Pigment cells are always very, very cool. I've been intrigued by them for a long time — they show up in my time-lapse recordings of developing zebrafish and are always active. Here's a quick one, a few hours of time in a roughly 24 hour old zebrafish embryo, compressed to about 30 seconds. You can see one corner of the dark eye at the bottom left of the image, and that oval structure near the middle with two spots in it is the…
pharyngula | December 29, 2009Don't miss it! Tonight at 8pmET/7pm Central, NOVA is showing What Darwin Never Knew, a documentary about evo-devo. I shall be glued to my TV tonight!
I just started watching it. So far, it's a nice little history of Darwin and his ideas; Sean Carroll is a good person to have talking up the story. It's nothing new yet, and nothing about evo-devo so far — I'm waiting impatiently for it.
Twenty minutes in, we get a little embryology: limb rudiments in snake embryos, tooth rudiments in whale embryos, and branchial arches in human embryos. These are shown as uncompromising evidence of limbed,…
pharyngula | November 30, 2009I'm going to be opening my mouth again on Thursday in Minneapolis — I'll be giving a talk in MCB 3-120 on the Minneapolis campus at 7:30 on Thursday, 3 December. This will be open to the public, and it will also be an all-science talk, geared for a general audience. I'd say they were going to check your nerd credentials at the door, but just showing up means you're already fully qualified.
The subject of the talk is my 3 big interests: a) evolution, or how we got here over multiple generations, b) development, or how we got here in a single generation, and c) the nervous system, the most…
edyong | November 30, 2009This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science.
Attention-deficit hyperactivity disorder is the most common developmental disorder in children, affecting anywhere between 3-5% of the world's school-going population. As the name suggests, kids with ADHD are hyperactive and easily distracted; they are also forgetful and find it difficult to control their own impulses.
While some evidence has suggested that ADHD brains develop in fundamentally different ways to typical ones, other results have argued that they are just the result of a delay in the…
pharyngula | November 15, 2009My little laptop is functional again, so at least I'll be able to blog these Sunday morning IGERT sessions in real-time. I still have to transcribe my notes from yesterday; I'll plan on getting that done on the plane this afternoon.
Kristi Montooth: Mitochondrial-nuclear epistasis for metabolic fitness in flies
How do physiological systems evolve to maintain metabolic fitness? This is a process that involves interactions between two genomes, the nuclear and mitochondrial. Energy metabolism is important and is the target of mutation, but the same players are found all across the tree of life…
pharyngula | November 4, 2009Last week, I described the lectures I attended at the Chicago 2009 Darwin meetings (Science Life also blogged the event). Two of the talks that were highlights of the meeting for me were the discussions of stickleback evolution by David Kingsley and oldfield mouse evolution by Hopi Hoekstra — seriously, if I were half my age right now, I'd be knocking on their doors, asking if they had room for a grad student or post-doc or bottle-washer. They are using modern techniques in genetics and molecular biology to look at variation in natural populations in the wild, and working out the precise…
pharyngula | October 31, 2009Shubin had a tough act to follow, coming after Kingsley's great talk. I'm sure it will be good, though — last night I got a tour of his lab, saw the original Tiktaalik specimens and some new ones, and some of his work in progress (which I won't tell you about until it's published), so I'm confident I'm going to have a happy hour.
Darwin pulled together diverse lines of evidence to document his ideas. The different lines all reinforce each other making the argument even stronger, and what we're seeing now is new syntheses, which is the theme of this talk: how do we use different lines of…
pharyngula | October 31, 2009This talk should put me back in my comfort zone—developmental biology, evolution, and fish, with the stickleback story, one of the really cool model systems that have emerged to study those subjects.
What is the molecular basis of evolutionary change in nature? How many genetic changes are required to produce new traits? Which genes are used? What types of mutations? Few or many changes required?
The dream experiment would be to cross a whale and a bat and figure out what their genetic differences are. That's impossible, so they searched for other organisms with a suite of differences that…
pharyngula | October 29, 2009Here's part of an explanation I've liked for a long time: they're a product of developing cognitive processes that bias the brain to model the world with supernatural shortcuts.
(Moved below the fold because the silly video defaults to autoplay.)
pharyngula | October 28, 2009I'm liking these CreatureCast videos from Casey Dunn — I showed the first in this series, now here's the second. It uses very simple animation to illustrate basic concepts…like the evolution of multicellularity in this one.
CreatureCast Episode 2 from Casey Dunn on Vimeo.
pharyngula | October 16, 2009I was just catching up on a few blogs, and noticed all this stuff I missed about Jonathan Wells' visit to Oklahoma. And then I read Wells' version of the event, and just about choked on my sweet mint tea.
The next person--apparently a professor of developmental biology--objected that the film ignored facts showing the unity of life, especially the universality of the genetic code, the remarkable similarity of about 500 housekeeping genes in all living things, the role of HOX genes in building animal body plans, and the similarity of HOX genes in all animal phyla, including sponges. 1Steve…
pharyngula | October 15, 2009
It's yet another transitional fossil! Are you tired of them yet?
Darwinopterus modularis is a very pretty fossil of a Jurassic pterosaur, which also reveals some interesting modes of evolution; modes that I daresay are indicative of significant processes in development, although this work is not a developmental study (I wish…having some pterosaur embryos would be exciting). Here it is, one gorgeous animal.
(Click for larger image)Figure 2. Holotype ZMNH M8782 (a,b,e) and referred specimen YH-2000 ( f ) of D. modularis gen. et sp. nov.: (a) cranium and mandibles in the right lateral view,…
pharyngula | September 16, 2009Look at the interesting snake found in China — it's got a leg.
How can this happen? Genes are pleiotropic — they tend to have lots of different functions. The genes involved in making a limb are also expressed in other places; for instance, the Hox genes that specify identity along the length of the body are also reused in specifying identity along the length of the limb. What that means is that when the snake evolved limblessness, it didn't do so by simply throwing away a collection of leg genes — it couldn't, not without also destroying genes that functioned in generating its body plan.…
edyong | August 5, 2009You wouldn't think it to look at our skyrocketing global population, but many parts of the world are experiencing serious falls in fertility. A country's fertility rate is the average number of children born to a woman over her lifetime. In most developed countries, it needs to be 2.1 or higher if the number of newborns is to compensate for citizens who die. In developing countries, where death is a more frequent visitor, this replacement threshold is even higher.
The problem is that declining fertility is intimately linked with a country's economic and social development. As a result, more…
pharyngula | August 4, 2009
We miss something important when we just look at the genome as a string of nucleotides with scattered bits that will get translated into proteins — we miss the fact that the genome is a dynamically modified and expressed sequence, with patterns of activity in the living cell that are not readily discerned in a simple series of As, Ts, Gs, and Cs. What we can't see very well are gene regulatory networks (GRNs), the interlinked sets of genes that are regulated in a coordinated fashion in cells and tissues.
What this means is that if you look within a specific cell type at a specific gene, its…
awild | August 4, 2009Here's an image for the textbooks:
Ants, like butterflies, pass through egg, larva, and pupa phases on their way to adulthood. While in Florida earlier in this summer I found a nest of the twig ant Pseudomyrmex gracilis with brood present in all stages, providing the material to make these images.
The key was placing the developing ants on a glass slide. This provided distance between them and the cardboard background, so that the backdrop is blurred while the insects remain in sharp focus. These images are not what I'd call fine art, but I'm happy with them as solid illustrations of ant…
pharyngula | July 21, 2009
PLoS has recently published a highly speculative but very interesting paper on how a particular signaling pathway, the Hedgehog pathway, might have evolved. It's at a fairly early stage in hypothesis testing, which is one of the things that makes it interesting — usually all you see published is the product of a great deal of data collection and experiment and testing, which means the scientific literature gives a somewhat skewed view of the process of science, letting the outsider mainly see work that has been hammered and polished, while hiding the rougher drafts that would better allow us…
pharyngula | July 17, 2009It's sad to see that we've lost Brian Goodwin, one of the genuinely original (but not always right!) thinkers of our time. There aren't many left of the old structuralist tradition in biology, the kind of non-genetic purists who tried to analyze development in terms of the fundamental physical and chemical properties of the organism—they've been swallowed up and lost in a triumphal molecular biology research program.
Edge has a nice interview with and essay by Goodwin — they're good places to start. If that whets your appetite, you should also read his book, How the Leopard Changed Its Spots…