evolution
evolvingthoughts | April 16, 2009Yes, I know there are thousands of these this year, and by October we'll all be tired of them, but this one looks like the main game: Darwin/Chicago 2009. I am, of course, upset not to be invited to speak, but there are a few good names there to make up for my absence...
razib | April 16, 2009Another response by Etienne Patin, lead author of Inferring the Demographic History of African Farmers and Pygmy Hunter-Gatherers Using a Multilocus Resequencing Data Set, to a follow up post:
As to your hypothesis represented by the cladogram, this is a quite reasonable and interesting idea. Actually, the only method that we could use to prove it is to find human remains of Pygmies dating back to Bantu expansions, in regions that were colonized by Bantus. Population genetics cannot infer the presence of extinct populations. However, as stated in our article, Western and Eastern Pygmies may…
jlynch | April 15, 2009
Apparently Mycocepurus smithii doesn't. It has become the first ant species to dispense completely with males. More details here.
(The picture above - from the Daily Mail story - is actually by Alex Wild but is unattributed)
sa smith | April 15, 2009Last year I wrote about a cool paper, arguing for the creation of a new polio vaccine.
Briefly, polio is an RNA virus, thus has an error-prone RNA-RNA polymerase, thus acts like a quasispecies like HIV-1. Now, a live attenuated polio vaccine is the 'best' because you activate lots of branches of your immune system, which 'remember' the polio virus for a really long time. But because of polios potential genetic diversity, the attenuated vaccine variant can revert back to the wild-type variant, which is 'more fit'.
This doesnt matter to you, because youve been vaccinated. But if you shed…
razib | April 15, 2009Genetic Evidence of Geographical Groups among Neanderthals:
The Neanderthals are a well-distinguished Middle Pleistocene population which inhabited a vast geographical area extending from Europe to western Asia and the Middle East. Since the 1950s paleoanthropological studies have suggested variability in this group. Different sub-groups have been identified in western Europe, in southern Europe and in the Middle East. On the other hand, since 1997, research has been published in paleogenetics, carried out on 15 mtDNA sequences from 12 Neanderthals. In this paper we used a new methodology…
bioephemera | April 14, 2009No, it's not how evolution really works, but it's awfully cool anyway.
The Experiment from Colin Trenter on Vimeo.
I love Photoshop, but am I the only one who thinks this resembles a cross between a Rorschach test and a SyFy Channel commercial?
mikethemadbiologist | April 14, 2009While I'm away on vacation, here's a blast from the past:
Once again, the science framing wars have flared up. While I'm not allergic to the concept of framing as some are, one of the major reasons why I'm not a big fan of dwelling on the topic is that obsessing over language reminds me of the late 80s and 90s when the Left won the battle of words, and the fundamentalist Uruk-hai took over the damn country.
I've been doing some thinking about the 'progressive' concern with media communication (including my own)--and it is important, no doubt about it. But, as the 2006 elections have shown,…
razib | April 14, 2009Accelerated Adaptive Evolution on a Newly Formed X Chromosome:
Sex chromosomes originated from ordinary autosomes, and their evolution is characterized by continuous gene loss from the ancestral Y chromosome. Here, we document a new feature of sex chromosome evolution: bursts of adaptive fixations on a newly formed X chromosome. Taking advantage of the recently formed neo-X chromosome of Drosophila miranda, we compare patterns of DNA sequence variation at genes located on the neo-X to genes on the ancestral X chromosome. This contrast allows us to draw inferences of selection on a newly…
pharyngula | April 13, 2009
My first column in the Guardian science blog will be coming out soon, and it's about a recent discovery that I found very exciting…but that some people may find strange and uninteresting. It's all about the identification of nodal in snails.
Why should we care? Well, nodal is a rather important — it's a gene involved in the specification of left/right asymmetry in us chordates. You're internally asymmetric in some important ways, with, for instance, a heart that is larger on the left than on the right. This is essential for robust physiological function — you'd be dead if you were…
edyong | April 12, 2009
Sponges are among the most primitive of all animals. They are immobile, and live by filtering detritus from the water. They have no brains or, for that matter, any neurons, organs or even tissues. If you were looking for the evolutionary origins of animal intelligence, you couldn't really pick a less likely subject to study.
So it was with great surprise that Onur Sakarya from the University of California, Santa Barbara found that sponges carry the beginnings of a nervous system.
With no neurons to speak of, these animals still have the genetic components of synapses, one of the most…
razib | April 11, 2009The leader author of the PLoS Genetics paper Inferring the Demographic History of African Farmers and Pygmy Hunter-Gatherers Using a Multilocus Resequencing Data Set, which I blogged a few days ago left a clarifying comment:
I just have few remarks. I do not expect that the Bantu expansions are responsible for the separation of Western and Eastern Pygmies. In a recent article in Current Biology, Paul Verdu and colleagues showed that the separation of Pygmy groups, but only those from the Western part of sub-Saharan Africa, diverged concomitantly with Bantu expansions (3,000-5,000 years ago…
razib | April 10, 2009Signatures of natural selection are not uniform across genes of innate immune system, but purifying selection is the dominant signature:
We tested the opposing views concerning evolution of genes of the innate immune system that (i) being evolutionary ancient, the system may have been highly optimized by natural selection and therefore should be under purifying selection, and (ii) the system may be plastic and continuing to evolve under balancing selection. We have resequenced 12 important innate-immunity genes (CAMP, DEFA4, DEFA5, DEFA6, DEFB1, MBL2, and TLRs 1, 2, 4, 5, 6, and 9) in healthy…
laelaps | April 10, 2009
An artist's restoration of Hurdia. From the Science paper.
It is not easy working on Cambrian fossils. The petrified treasures are found in only a few places in the world, and even though many exhibit exquisite preservation they come from a time when life on earth would have looked very unfamiliar. One such creature, Anomalocaris, was a three foot long invertebrate that swam by undulating a series of lobes on either side of its body. In front of its mouth were two spiked tendrils that may have helped situate prey items to be processed by its conveyor belt of crushing plates that was its…
evolvingthoughts | April 9, 2009Older histories of biology are often full of useful and interesting facts. One of my all-time favourites is Eric Nordenskiöld's history, but I came across an earlier one by Louis Compton Miall in which I found this text:
Bonnet in 1745 traced the scale of nature in fuller detail than had been attempted before. He made Hydra a link between plants and animals, the snails and slugs a link between mollusca and serpents, flying fishes a link between ordinary fishes and land vertebrates, the ostrich, bat, and flying fox links between birds and mammals. Man, endowed with reason, occupies the highest…
razib | April 9, 2009Inferring the Demographic History of African Farmers and Pygmy Hunter-Gatherers Using a Multilocus Resequencing Data Set:
The transition from hunting and gathering to farming involved a major cultural innovation that has spread rapidly over most of the globe in the last ten millennia. In sub-Saharan Africa, hunter-gatherers have begun to shift toward an agriculture-based lifestyle over the last 5,000 years. Only a few populations still base their mode of subsistence on hunting and gathering. The Pygmies are considered to be the largest group of mobile hunter-gatherers of Africa. They dwell in…
jlynch | April 9, 2009I'm currently reading Hoelldobler & Wilson’s The Superorganism and just ran across this post by Alex Wild which claims that
the whole section of The Superorganism devoted to the evolutionary history of ants is muddy, incoherent, and entirely at odds with the increasingly clear picture emerging from modern studies of ant relationships.
Alex is inaugurating Scienceblogs' new photoblog, Photo Synthesis, and will be guest-blogging for a month, so wander on over and check it out. His own blog is also worth a read and his photos (here and here) are excellent.
laelaps | April 9, 2009
When I first happened upon Sean B. Carroll's new book, Remarkable Creatures my first thought was "Damn! He beat me to it!" For over a year I have been preparing my own pop-sci book about paleontology, evolution, and the history of science, and as I skimmed through Remarkable Creatures I saw that Carroll had already covered a number of the same subjects. I would have been interested in Carroll's book regardless of my own project, but given my goal I knew I had to read it.
Fortunately for me Remarkable Creatures is not as similar to my own project as I had first thought. Instead it is a…
ddobbs | April 8, 2009The 10,000-year Explosion: How Civilization Accelerated Evolution, of which I've so far read about 1000 words -- but I just got it. Appears to be The Beak of the Finch (faster than expected evolutionary changes) in humans, but with this delicious addtion: the idea that culture can drive evolution, so that the line between "nature" (biology) and "nurture" (culture) finally vanishes. We'll see.
Sean Carroll's Remarkable Creatures, which got pre-empted (for work reasons) by the above-named Explosion. Looks quite juicy.
The Dangerous River, R.M. Patterson's account of his time exploring the…
grrlscientist | April 8, 2009tags: microbiology, astrobiology, new species, Indian Space Research Organization, bacteria
Bacterial colonies.
Image: Hub Testing Laboratory [larger view].
According to a recently published press release, three new species of bacteria have been discovered in the upper stratosphere by Indian scientists in an experiment conducted by the Indian Space Research Organization (ISRO). This discovery lends some credence to the hypothesis that life might have originated elsewhere in the cosmos and was seeded on Earth after colliding with a foreign body, perhaps a comet or asteroid, that was…