evolution
purepedantry | October 11, 2007Erez Lieberman et al. at Harvard are looking at the rate of change in words to see if words evolve:
Lieberman was struck by this idea when he learned that the ten most common verbs in English (be, have, do, go, say, can, will, see, take, get) are all irregular. Instead of their past tenses ending in '-ed', as do 97% of English verbs, they take the peculiar forms of was, had, did, went, said, could, would, saw, took and got.
Researchers suppose that this is because often-used irregulars are easy to remember and get right. Seldom-used irregulars, on the other hand, are more likely to be…
loom | October 11, 2007We do a pretty good job at appreciating the visible intricacies of nature: the antennae and legs and claws of a lobster, the geometrical order of the spots on a butterfly's wings. But a lot of nature's intricacies are hidden away inside single-celled creatures, such as the baker's yeast that makes bread rise and beer ferment. At an audition for a David Attenborough documentary, a yeast cell guzzling away on sugar is bound to do a lousy job. ("Thanks, don't call us; we'll call you. Send in the King Cobra!") But the intricacy of its metabolism is no less impressive. What's more, scientists know…
jrosenhouse | October 10, 2007My reviews of Phillip Kitcher's Living With Darwin and Francisco Ayala's Evolution and Intelligent Design are now available over at Skeptic's website. Enjoy!
I should probably mention that I wrote this review some time ago, and in the meantime Ayala has published a slightly more detailed book on the same subject, entitled Darwin's Gift. I got about fifty pages into it before being sidetracked by other reading. I'll withhold final judgment until I've read the whole thing, but my impression is that the new book gives me no reason to revise my opinion of Ayala's arguments.
evolgen | October 10, 2007Please God, don't let it happen. Please don't let Franky Collins win this stupid award. I don't usually make pleas to you, but, given that this is a matter regarding a man of faithTM, I figured it's a good time to plea to the sky fairy. So, do whatever you can to prevent Congress from awarding Frank the medal.
As for my more terrestrial readers, here's the skinny. The Genetic Alliance is petitioning the US Congress to award Collins the Congressional Gold Medal. Why? Because he's in charge of the National Human Genome Research Institute (NHGRI). Now, the NHGRI has done a great job in promoting…
loom | October 10, 2007Science writer Jessica Snyder Sachs has an interesting op-ed in today's New York Times, explaining why you should get your flu shot and skip the chicken pox parties. It's a taste of the material in her excellent new book, Good Germs, Bad Germs: Health and Survival in a Bacterial World (Full disclosure: I provided a blurb for the book.)
pharyngula | October 9, 2007
Early Cambrian shrimp! I just had to share this pretty little fellow, a newly described eucrustacean from the lower Cambrian, about 525 million years ago. It's small — the larva here is about 1.8mm long, and the adults are thought to have been 3mm long — but it was probably numerous, and I like to imagine clouds of these small arthropods swarming in ancient seas.
The head limbs are drawn in median view and the trunk limbs in lateral view.
There are a couple of notable things about this animal. One is that they're preserved in full 3-dimensional detail in an Orsten-type lagerstätte, which…
clock | October 9, 2007Another thing I will also have to miss - the Inaugural Event of the 2007-2008 Pizza Lunch Season of the Science Communicators of North Carolina (SCONC), on October 24th at Sigma Xi Center (the same place where we'll have the Science Blogging Conference). Organized by The American Scientist and the Burroughs Wellcome Fund, the first Pizza Lunch Session will feature Dr.Fred Gould, professor of Entomology and Genetics at NCSU (whose Insect Ecology class blows one's mind - one of the best courses I have ever taken in my life). Fred recently received The George Bugliarello Prize for an…
razib | October 9, 2007The paper Genetic Evidence for the Convergent Evolution of Light Skin in Europeans and East Asians has some great maps which show the frequencies of major alleles for some major skin color genes. I've placed them below the fold with some minor edits (added the gene label prominently to each map).
razib | October 8, 2007An Open Access review paper in Human Molecular Biology, Challenges in human genetic diversity: demographic history and adaptation, has a short and easy-to-digest review of many of the major findings over the past 5 years in human evolutionary genomics and the "big picture" implications:
Modern human genetic diversity is the result of demographic history, and selective effects that have acted to adapt different populations to their environments. Broad patterns of global diversity are well explained by geography, based on an out-of-Africa model of early human evolution. Genome-wide searches for…
razib | October 8, 2007Ancestral reconstruction of segmental duplications reveals punctuated cores of human genome evolution:
Human segmental duplications are hotspots for nonallelic homologous recombination leading to genomic disorders, copy-number polymorphisms and gene and transcript innovations. The complex structure and history of these regions have precluded a global evolutionary analysis. Combining a modified A-Bruijn graph algorithm with comparative genome sequence data, we identify the origin of 4,692 ancestral duplication loci and use these to cluster 437 complex duplication blocks into 24 distinct groups…
pharyngula | October 7, 2007
I've written a long introduction to the work I'm about to describe, but here's the short summary: the parts of organisms are interlinked by what has historically been called laws of correlation, which are basically sets of rules that define the relationship between different characters. An individual attribute is not independent of all others: vary one feature, and as Darwin said, "other modifications, often of the most unexpected nature, will ensue".
Now here's a beautiful example: the regulation of the growth of mammalian molars. Teeth have long been a useful tool in systematics—especially…
pharyngula | October 6, 2007John Dennehy's citation classic this week is The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme, by Gould and Lewontin. It's one of my favorite papers of all time — if you haven't read it, you should do so now. It contains a set of ideas that are essential to understanding evo-devo.
Gould always struck me as a closet developmental biologist — he should have studied it more!
pharyngula | October 6, 2007Cuvier, and his British counterpart, Richard Owen, had an argument against evolution that you don't hear very often anymore. Cuvier called it the laws of correlation, and it was the idea that organisms were fixed and integrated wholes in which every character had a predetermined value set by all the other characters present.
In a word, the form of the tooth involves that of the condyle; that of the shoulder-blade; that of the claws: just as the equation of a curve involves all its properties. And just as by taking each property separately, and making it the base of a separate equation, we…
evolvingthoughts | October 6, 2007
I found this interesting and still surprisingly modern essay by David Starr Jordan in 1897, at William Tozier's blog, where he had scanned it from a journal called The Arena. They had some good public discussion journals at the time.
So I took his scan and OCR'd and corrected it, and put it here. It is amazing how well Jordon managed to avoid the usual errors, and correct those that are with us still, so long ago.
The essay is beneath the fold. I left the headers in.
THE ARENA.
Vol. XVIII.AUGUST, 1897.No. 93.
EVOLUTION: WHAT IT IS AND WHAT IT IS NOT.1
BY DR. DAVID STARR…
evolvingthoughts | October 5, 2007
On Monday night last, Jason Grossman, a philosopher form the Australian National University rang me with an idea. He was coming to my university to give a talk entitled "How to Feyerabend", arguing that Feyerabend was a dadaist rather than an anarchist. I'd tell you more about his talk, but I can't, for reasons that will become obvious.
He wanted to do the talk as a dadaist performance. How can I help? I enquired. That was my mistake.
Well, he said, I want us to give a simultaneous presentation. What, in turn? I asked. No, at the same time. With music. And Allison (his partner) folding…
grrlscientist | October 4, 2007tags: researchblogging.org, Brown paper wasp, Polistes fuscatus, hymenoptera, evolution, eusociality, social behavior
Brown paper wasp , Polistes fuscatus.
Fairport, New York, USA. 2003.
Many thanks to Alex Wild for sharing his amazing images here.
Thanks to Elizabeth Tibbetts for the species identification.
[larger view]
Eusociality, or "true social behavior", is the most extreme form of cooperative sociality known. Due to its seemingly altruistic nature, eusociality has provided many interesting challenges for evolutionary theory. Eusociality, as exemplified by ants, bees and wasps, is…
pharyngula | October 3, 2007Tristero makes a few points that are exactly what I've been trying to get across in my introductory biology class this week, where we're covering Charles Darwin and the evidence for evolution. The first is that we do not rely on Darwin's authority; there is no cult of personality, no reliance on the master's word, no simple trust of anything or anyone. The other, though, is that Darwin is still a fascinating and important figure, and it's not just that he was an old guy with a white beard who lectured the law.
Darwin's not a stuff-shirted Nigel Bruce pip-pipping his way across the Empire. He…
voltagegate | October 3, 2007I've been reading up on this critter for the past few days, ever since I pulled out some old mammal texts I had sitting on the shelf. I got sucked in and thought I would share a bit of what I've read.
The volcano rabbit, Romerolagus diazi, is found on the slopes of only four volcanoes in Mexico, south of Mexico city. These four - Pelado, Iztacohuat, Tlaloc and Popocatepetl - are part of the transvolcanic belt (TVB; also called the trans-Mexican volcanic or transverse neovolvanic belt), a biogeographic zone in the center of the country that exhibits a high level of endemism; in other words,…
mikethemadbiologist | October 2, 2007One of the major fallacies of intelligent design creationism is that so many structures appear to be haphazardly designed. Case in point: polyadenylation in Giardia lamblia. ScienceBlogling Carl Zimmer, in an excellent post about the recently published Giardia genome, describes the system:
There's all sorts of fascinating stuff lurking in Giardia's genome. As they surveyed its 6470 genes, the genome team was struck by how simple Giardia is, compared to other eukaryotes. I think this diagram in particular does a nice job of illustrating Giardia's simplicity. The top drawing shows what…
razib | October 1, 2007Archaeology: Sharp shift in diet at onset of Neolithic:
The introduction of domesticated plants and animals into Britain during the Neolithic cultural period between 5,200 and 4,500 years ago is viewed either as a rapid event or as a gradual process that lasted for more than a millennium. Here we measure stable carbon isotopes present in bone to investigate the dietary habits of Britons over the Neolithic period and the preceding 3,800 years (the Mesolithic period). We find that there was a rapid and complete change from a marine- to a terrestrial-based diet among both coastal and inland…