evolution
pharyngula | October 1, 2007
All of us mammals have pretty much the same set of genes, yet obviously there have to be some significant differences to differentiate a man from a mouse. What we currently think is a major source of morphological diversity is in the cis regulatory regions; that is, stretches of DNA outside the actual coding region of the gene that are responsible for switching the gene on and off. We might all have hair, but where we differ is when and where mice and men grow it on their bodies, and that is under the control of these regulatory elements.
A new paper by Fondon and Garner suggests that there…
pharyngula | October 1, 2007Here's a website of mutating pictures, a collection of images made with a splatter of scattered triangles. Your job is to browse through them and score them for how much they resemble a face — which isn't easy. If I stare at any random pile of symmetrical shadings, they all start to look like faces to me.
Anyway, pictures that get higher scores produce more progeny, with slight mutations, in the next round of picture generation. You can see where this is going…
evolvingthoughts | September 30, 2007
Thinking some more about PZ's latest comedic act, I think I see what the problem is.
People do not change their beliefs just because someone offends them. They change their beliefs because opponents offend them. If someone is a Muslim, they won't become an Islamist because another Muslim teaches something different, but because that Muslim is a member of an opposing sect. The friend of my enemy is my enemy.
There is not exactly a continuum of ideas between theism and atheism, because there is not a single dimension or variable along which a continuum might be drawn as a spectrum. But…
razib | September 30, 2007I don't know if we should believe Svante Pääbo anymore, but his lab has some new findings re: Neandertal mtDNA:
Neanderthals in central Asia and Siberia
Nature advance online publication 30 September 2007. doi:10.1038/nature06193
Authors: Johannes Krause, Ludovic Orlando, David Serre, Bence Viola, Kay Prüfer, Michael P. Richards, Jean-Jacques Hublin, Catherine Hänni, Anatoly P. Derevianko & Svante Pääbo
Morphological traits typical of Neanderthals began to appear in European hominids at least 400,000 years ago and about 150,000 years ago in western Asia. After their initial…
loom | September 29, 2007My talk with John Horgan on bloggingheads.tv is up. I'm sure the fact that the label "weird life" appears directly over my head was an accident (right, John?). Anyway, we had a good talk about parasites, aliens, and how to handle hype in science. I may have made some mistakes--feel free to fact-check in the comment thread. Unfortunately, I can't strike out my spoken errors, but we can make the best of it. (If you hanker for more scienceblog/bloggingheads encounters, see these talks by PZ Myers and Chris Mooney.)
grrlscientist | September 27, 2007tags: researchblogging.org, Seychelles warbler, Acrocephalus sechellensis, birds, evolution, social behavior, helping behavior, grandmothers
Seychelles warbler, Acrocephalus sechellensis.
Image: J. Komdeur.
When talking about evolution, some people have wondered aloud about why grandmothers exist in human society since they clearly are no longer able to reproduce. However, these people are conveniently overlooking the fact that grandmothers perform a valuable service; they help their relatives, often their own children, raise their offspring -- offspring that are genetically related to…
loom | September 27, 2007It is a day to write about Giardia, and I am happy to say that I cannot do so from firsthand experience. Friends of mine have suffered infections of Giardia in their gut, but they haven't been terribly forthcoming about the details. It's not fun, they assure me, and it can last for months. Unpleasant as it may be up close, though, Giardia is one of the most fascinating, most enigmatic creatures on the planet (from a safe distance). Scientists do not yet quite know what to make of this single-celled parasite, but one possibility is that Giardia holds secrets to some of the key steps in the…
evolgen | September 27, 2007Or is he micro-phobe?
Nature Genetics has published a mostly positive review of the new Evolution textbook by Nick Barton and others (the others include blogger Jonathan Eisen) The review is penned by Francisco Ayala. Among the things Ayala brings up is the coverage various taxa receive:
Surprisingly, however, five of the nine chapters of Part II are dedicated to the history of microbial evolution, and only one chapter deals with the diversification of plants and animals.
So, of the nine chapters in Part II, six deal with particular groups of organisms. Of those six, five focus on microbial…
mikethemadbiologist | September 26, 2007In response to this blast from the past about Kuhnian scientific revolutions, SteveG has an interesting discussion about the inadequacy of Popperian falsification for understanding paradigm shifts, or to use Imre Lakantos' phrase "research programme" (italics mine):
Imre Lakatos was a student of Popper's who also found certain things about Kuhn's view deeply attractive. He realized the problems with the use of falsifiability of individual hypotheses as a criterion of demarcation for science that arose from Kuhn's insights. but he also saw one of the glaring problems with Kuhn's system. If a…
evolvingthoughts | September 24, 2007
This is a nice post by Christopher Taylor at Catalogue of Organisms, a kiwi studying spider systematics (and what's not to love about that; cephalopods be buggered!) on the species of moas that used to live in New Zealand. I didn't realise they'd be forest dwellers. It's a worthwhile blog to get the feed for.
grrlscientist | September 24, 2007tags: researchblogging.org, social behavior, evolution, Psittacosaurus, ornithischian dinosaur
Triceratops.
Image: Dinosaur Collector
Triceratops are among the most recognizable dinosaurs because of their distinct appearance. They had a large and elaborate bony shield around the back of their head, horns that jut out from the top of their head and nose like spears, and bony knobs on their cheeks. Because these large structures are energetically expensive to grow, they had to serve a purpose and this purpose was likely the establishment of social hierarchies. Thus, these ornaments provide…
razib | September 24, 2007The New Republic has a piece titled The Greatest Dying by Jerry Coyne & Hopi E. Hoekstra (see below the fold for how to read it for free if you don't have a TNR subscription). The piece covers the a) general parameters of the mass extinction and b) the reasons why we should care. Coyne and Hoekstra immediately start out making the humanistic utilitarian case, i.e., "How does this help humanity be healthy, wealthy and secure?" But, they proceed to add near the end:
Our arguments so far have tacitly assumed that species are worth saving only in proportion to their economic value and…
clock | September 24, 2007Sarah Wallace, Matt Ford, ScienceGoGo and Jason Stajich comment on the fungus that gets its energy from radiation. I've heard of Deinococcus radiodurans before, but this is a fungus! Well, if there is an energy source to tap into, even if it is in the middle of Chernobyl, some life form is likely to find a way to do it.
grrlscientist | September 24, 2007tags: symbiosis, humor, The Onion
Those of you who haven't noticed this yet, The Onion has a really amusing article about symbiosis that you have got to read .. it might even make a really amusing "extra reading" for the classroom!
Devouring horsefly larvae embedded in her 3,000-pound partner's back, the tickbird seemed to agree that there was little fire left in their symbiotic relationship. At worst, she said, it feels like she and the rhino have been trapped in the same dead-end symbiosis for "countless millions of years."
"We just go through the motions, and there's hardly any…
grrlscientist | September 24, 2007tags: researchblogging.org, velociraptor, Dromaeosauridae, dinosaur, feathers, paleontology, evolution
Velociraptor skull.
Velociraptors were small dinosaurs, weighing only about 15kg and approximnately 1.5m long.
Image: M. Elison, AMNH. [larger view]
According to a research paper that was published late last week, the Velociraptor probably had feathers. A closer look at a fossil Velociraptor ulna (forearm) that was found in Mongolia in 1998 revealed a series of small bumps along its length. These bumps are known as "quill knobs" because they are found in most modern birds where they…
grrlscientist | September 24, 2007tags: encephalon, brain, behavior, cognition, neurobiology, blog carnival
The last frontier: The brain.
Orphaned Image. Contact me so I can provide credit and linkage.
Several months ago, I was invited to host Encephalon, probably because I send so many submissions to this blog carnival and possibly also because I am fairly good at sending traffic to the contributors of those blog carnivals that I host. Unfortunately, I have not had wifi for the past two days, so I hope that you appreciate my modest efforts on behalf of this blog carnival. So, without further ado, I present to you the 32nd…
pharyngula | September 23, 2007
One concept that is sometimes used in developmental biology is the idea of the "master control gene" or "master switch" — a single gene whose expression is both necessary and sufficient to trigger activation of many other genes in a coordinated fashion, leading to the development of a specific tissue or organ. It's a handy concept on which to hang a discussion of transcription factors, but it may actually be of rather limited utility in the real world of molecular genetics: there don't seem to be a lot of examples of master control genes out there! Pax-6 is the obvious one, a gene that…
evolvingthoughts | September 22, 2007
On Friday I assessed an essay by a masters student on the evolution of reciprocity and altruism (she cleverly introduced a notion of benevolent behaviour rather than "altruism" in social contexts, to avoid confusion with genetic altruism.
Then today my various feeds identified this rather excellent essay (more of a review paper, really) on strong reciprocity (the idea that we humans will behave reciprocally even if there is no individual payoff) by Benoit Hardy-Valée, of the University of Toronto. In this paper, he challenges what he calls "The Collective", a group of conservative…
mikethemadbiologist | September 22, 2007A follow up to yesterday's blast from the past:
Ever since Majikthise, Pandagon, and Alternet linked to my post about Yglesias, my sitemeter hit-counter thingee has blown a gasket (and, Majikthise, um, thanks for the very kind words, but low expectations are much easier to live with...). Anyway, it's been interesting to read what other people think about the post.
One general angle I've noticed is that many commenters are focusing on the politics of evolution. Granted, this post was picked up largely by political websites, so this is to be expected. Regarding the politics, I'm not naive: I…
evolvingthoughts | September 22, 2007
One of the things I have previously discussed (see the "Best of ET" tab) is microbial species concepts. Two new papers have come out on this, and it seems to be a hot research topic right now.
Eppley, et al., in the journal Genetics, argue that the claim that I happened to make in my as-yet unpublished paper in History and Philosophy of the Life Sciences, that microbial species are clusters of genomes maintained by, among other things, homologous recombination of genes, is supported by experimental evidence based on genomic data of two microbial species of Archae bacteria, of the genus…