razib | July 27, 2007Rapid evolution in early trilobites fueled by high variation:
Webster compiled morphological data for nearly 1,000 of the 17,000 different species of trilobites, a class of marine arthropods that died out by 250 million years ago, from 49 previously published sources. By tracking different morphological features -- the number of body segments, for example -- Webster found that trilobite species exhibited more variation during the Cambrian than in later periods, he reported in Science July 27. "Once you go beyond the Cambrian, the diversity of forms within any one species drops off," he says.…
razib | July 27, 2007How bacteria evolve into superbugs:
"Bacteria that can mutate fast will quickly adapt to harsh environments containing antibiotics. Our study showed that a high rate of immigration significantly augments the regular process of genetic mutation commonly used to explain the evolution of antibiotic resistance," said co-author Dr. Andrew Gonzalez, a Canada Research Chair in Biodiversity and associate professor in the Department of Biology at McGill. Gonzalez explained that the flow of bacteria in the experiment is analogous to the immigration of bacteria-carrying individuals into a hospital, and…
razib | July 26, 2007Looks like there might be a recantation of the argument against death for apostasy by the Grand Mufti of Egypt. Abu Aardvark has the details.
razib | July 26, 2007Viral Epizootic reveals inbreeding depression in a habitually inbreeding mammal:
Inbreeding is typically detrimental to fitness. However, some animal populations are reported to inbreed without incurring inbreeding depression, ostensibly due to past "purging" of deleterious alleles. Challenging this is the position that purging can, at best, only adapt a population to a particular environment; novel selective regimes will always uncover additional inbreeding load. We consider this in a prominent test case: the eusocial naked mole-rat (Heterocephalus glaber), one of the most inbred of all free…
razib | July 25, 2007If you find the material on this blog of interest, I highly recommend that you subscribe to Jason Malloy's de facto clipping service: http://tech.groups.yahoo.com/group/gnxpforum/. A far number of the articles I blog about I find via that entry on my RSS....
razib | July 25, 2007Check out a long piece on bonobos in The New Yorker. Now, I've read a fair amount of Frans de Waal's work, and I think the piece is making him out to be a little more PC than he is. Nevertheless, I am a bit disturbed by the fact that hasn't seen a Bonobo in the wild! I just happened to have missed that assumed that though most of his research was based on captive animals, there must have been some field research supplementing it. No. And de Waal's response it pretty lame:
Captivity can have a striking impact on animal behavior. As Craig Stanford, a primatologist at the University of…
razib | July 25, 2007I was putting off commenting on this, and wondering whether I had any value to add. But a reader pointed me to Noah Feldman's Orthodox paradox, a piece in The New York Times Magazine where the author, a young Harvard law professor, reflects on his journey from the Modern Orthodox subculture into the wider world. The whole piece is worth reading. There is a problem in these sorts of articles insofar as Feldman is such an "insider," while most of the readers are such "outsiders," that one is totally dependent on the author for context and situation. For example, most gentiles have…
razib | July 24, 2007Update II: John Hawks leaves a comment.
Update: Kambiz has much more comment.
Were neandertal and modern human cranial differences produced by natural selection or genetic drift?:
... Here we use a variety of statistical tests founded on explicit predictions from quantitative- and population-genetic theory to show that genetic drift can explain cranial differences between Neandertals and modern humans. These tests are based on thirty-seven standard cranial measurements from a sample of 2524 modern humans from 30 populations and 20 Neandertal fossils. As a further test, we compare our results…
razib | July 24, 2007Ali Eteraz points me to the fact that the Grand Mufti of Egypt seems to have offered the opinion that 'Muslims can choose their own religion'. This is important, because as Wikipedia says:
All five major schools of Islamic jurisprudence agree that a sane male apostate must be executed. A female apostate may be put to death, according to some schools, or imprisoned, according to others.
Some contemporary Shi'a jurists, scholars, writers and Islamic sects have argued or issued fatwas that either the changing of religion is not punishable or is only punishable under restricted circumstances,…
razib | July 23, 2007Most of you could probably guess that my first post on Harun Yahya was meant to highlight what a joke the whole affair was. You see, making fun of Harun Yahya and his fellow travelers is a guiltless pleasure: you get to be snobby and elitist toward those idiotic moronic knuckle-draggers, and, you feel righteous about it because you're on the side of the angels!. How much of a hilarious incident was this? The first segment of Bloggingheads.tv was devoted to it, and the two pundits, neither of whom had a science background, thought it was pretty sneer and smirk worthy. That's what I told…
razib | July 23, 2007The Mastodon paleogenomics paper is out on PLOS:
We obtained the sequence from a tooth dated to 50,000-130,000 years ago, increasing the specimen age for which such palaeogenomic analyses have been done by almost a complete glacial cycle. Using this sequence, together with mitochondrial genome sequences from two African elephants, two Asian elephants, and two woolly mammoths (all of which have been previously sequenced), we show that mammoths are more closely related to Asian than to African elephants. Moreover, we used a calibration point lying outside the Elephantidae radiation (elephants…
razib | July 21, 2007Science makes DNA breakthrough in the tooth of a mastodon:
...after finding DNA preserved in the fossilised tooth of a beast that died up to 130,000 years ago.
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Researchers were hoping its teeth might have preserved enough of the DNA for them to recover lengthy chunks of it, and this week they will publish research detailing how their hunch has paid off. The find has allowed them to reconstruct the entire sequence of the DNA found in the creature's mitochondria, the parts of cells concerned with energy production. It is thought to be the oldest DNA ever to have been recovered and decoded…
razib | July 21, 2007Mike offers his 2 cents on the levels of selection debates. He says:
If it doesn't provide me with testable hypotheses and the conceptual tools to do so, it's just not useful. That's what happened the last go around with this in the late 80s and early 90s. Do the experiments and I'll be interested, because the last time it was a lot of yak and very little data.
Focusing on the "replicators" as opposed to the "vehicles" is so appealing because the former is so easier to grasp on to than the latter.
razib | July 20, 2007A reader points out that Fields Medalist Terrence Tao has a post on introgression in Darwin's Finches.
razib | July 20, 2007Update: John Hawks weighs in. Here is the abstract.
Several people have asked about a new paper coming out that uses the diversity in skulls to "prove" the Out of Africa hypothesis. The paper is going to be out in Nature yesterday. Yes, you read that right, it was supposed to be on the site on the 19th, but it still seems embargoed. But here is the headline from ScienceDaily, New Research Proves Single Origin Of Humans In Africa. Press releases are generally a little inflated, so no worries.
The basic gist is that the authors used the variation in skulls to trace population bottlenecks…
razib | July 19, 2007Natural polymorphism affecting learning and memory in Drosophila:
Knowing which genes contribute to natural variation in learning and memory would help us understand how differences in these cognitive traits evolve among populations and species. We show that a natural polymorphism at the foraging (for) locus, which encodes a cGMP-dependent protein kinase (PKG), affects associative olfactory learning in Drosophila melanogaster. In an assay that tests the ability to associate an odor with mechanical shock, flies homozygous for one natural allelic variant of this gene (forR) showed better short-…
razib | July 18, 2007Go Ahead, Everyone Talk at Once:
People who can't follow a movie when someone else is talking can blame their genes. The ability--or inability--to listen to more than one thing at once is largely inherited, according to a study of twins. The finding could help scientists better understand disorders that involve problems in auditory processing.
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"This is the first study to show that [normal] people vary widely in their ability to process what they hear, and these differences are due largely to heredity," NIDCD director James Battey said in a statement. That's important, says Deborah…
razib | July 18, 2007We know that the Magyars originated from Inner Eurasia. They were one of the long line of steppe peoples who conquered and settled central Europe, the Avars being their local predecessors. But unlike the Avars, or the Bulgars or the Huns, the Magyars left a cultural imprint: their language. And yet physically and genetically the current Hungarian population seems to exhibit continuity with their European neighbors (in contrast, Gypsies show evidence of haplotypes normally found in the Indian subcontinent). Dienekes points me to some new data:
Strong differences appear when the ancient…