genetics
razib | July 27, 2006Seed has a piece on the discoveries relating to menopause and its importance to the "Grandmother Hypothesis." Unlike male decline in fertility menopause is a specific and deliberate sequence of proactive processes by the female body to shut down reproductive capacity. Something like this is almost certainly functionally significant, and anthropological work which seems to show cross-cultural evidence of lower infant mortality in the presence of a maternal grandmother in the household is another important avenue in the overall program.
razib | July 26, 2006Here is the definition from Wiki:
Introgression is a term used in genetics, particularly plant genetics, to describe the movement of a gene from one species into the gene pool of another by backcrossing an interspecific hybrid with one of its parents. Introgression of a transgene from a transgenic plant to a wild relative as the result of a successful hybridization is an example.
Illustration. You have a Eastern European mouse and a West European mouse. On the boundary between the two species West European females mate with East European males, and the F1 hybrid females mate only with East…
razib | July 26, 2006Since Jonah posted on the French IQ study profiled in The New York Times Magazine, I thought I'd point to an analysis of the data by a co-thug over at GNXP Classic. Warning, if 2 X 2 ANOVA bores you, prepare to be bored. Otherwise, enjoy.
Update: Alex has more analysis.
razib | July 26, 2006Update: It maybe that "idiot commenter" speaks English as a second language , and so was not expressing his skepticism with sufficient nuance for my taste. That being said, this post stands as a warning to those who would waste my time.
-God Bless, Razib
This commenter starts out by admitting that he didn't follow all my reasoning in my post on Neandertal admixture, but proceeds to take a patronizing tone. What bullshit. I know that some of my posts make recourse to terms which are a bit technical, in fact, terms which I myself didn't grasp well until a few years ago, and whose conceptual…
razib | July 24, 2006I am a little unsure whether this article in The Washington Post titled And the Evolutionary Beat Goes On . . ., beginning with the sentence "Stephen Jay Gould would have been pleased," is a subtle joke or not. The journalist has a science background, and has even covered the evolution "controversy," but that doesn't really prepare you to dive into the brand new world of evolutionary genomics.
Here is the short of it. First, biases on the table, to say that I am not a Gouldian is charitable. I would argue that evidence of recent human evolution and diversification seems to be positively un…
razib | July 23, 2006Robert Skipper has an enormous post on R.A. Fisher & Sewall Wright's theories of dominance. I think Wright was more in the right on this issue, remember, it is easier to break (lose function) than make (gain function).
razib | July 22, 2006I have mentioned a few times that I am re-reading The Genetical Theory of Natural Selection by R.A. Fisher. I read it a few years back when I didn't know anything about evolutionary theory, so I believe this run through will be more frutiful. For those of you who don't know, R.A. Fisher was possibly the most important evolutionary biologist, and probably most important statistician, of the 20th century. Along with Sewall Wright and J.B.S. Haldane he created the field of theoretical population genetics which the Neo-Darwinian Synthesis takes as an a priori starting point. I know that in…
clock | July 21, 2006I had lunch with Anton yesterday. We talked about the upcoming busy blogging Fall and he showed me his new book.
We ate in my neck of the woods, at Town Hall Grill in Southern Village in Chapel Hill. Anton brought his laptop - the wi-fi signal is strong, so, after Brian and Ruby get married tomorrow (OK, they already are), Brian can add this restaurant to the Chapel Hill Wireless map.
Being very hungry, and knowing that the food there is delicious, I came prepared. While Anton had their lightly-battered fish and chips, I ordered a NY strip.
When the food arrived I reached down into my…
evolgen | July 21, 2006The third edition of Mendel's Garden -- the genetics blog carnival -- has been posted at Viva la Evolucion. Nothing like a blog with a Spanish language flavor hosted by an Irish website. Check out los artÃculos de genética.
razib | July 20, 2006Most of you probably know this, but the race is on to sequence the Neandertal genome. Nick Wade has a decent story on it. Important point:
The chimp and human genomes differ at just 1 percent of the sites on their DNA. At this 1 percent, Neanderthals resemble humans at 96 percent of the sites [the first 3 million base pairs], to judge from the preliminary work, and chimps at 4 percent.
No surprise, the putative last common ancestor between chimps and humans is 6 million years BP, Neandertals and modern humans is 500,000 years BP, and order of magnitude difference.
But these "last common…
razib | July 20, 2006The post below on the genetics (and relaxation of constraint) of dogs has given rise to many good comments. I want to highlight one:
...Yet most feral dog populations quickly revert to a medium-sized, short-coated, yellowish dog - the so-called "Pariah Dog" that's found in so many places around the world - why don't the feral populations look more like their wolf ancestors?
There are many issues mooted below. But this comment is a good one. Why do dogs "revert" into pariah dogs instead of the Eurasian wolf? Remember what is happening here: being as "cute" as a poodle doesn't matter once…
evolgen | July 20, 2006If you could have practiced science in any time and any place throughout history, which would it be, and why?
That's what they are asking us this week. And, once again, I'm going to skirt the question. You see, it depends on whether the future counts as a "place throughout history." Currently, the future is not history, but it will be history once the future becomes the past. You'll probably need a few minutes to digest that, as I must have just blown your mind. Or not.
My chosen place in time (yeah, I abandoned the whole history thing): the day of the $1000 genome. This is the population…
pharyngula | July 20, 2006Books from Nobel laureates in molecular biology have a tradition of being surprising. James Watson(amzn/b&n/abe/pwll) was catty, gossipy, and amusingly egotistical; Francis Crick(amzn/b&n/abe/pwll) went haring off in all kinds of interesting directions, like a true polymath; and Kary Mullis(amzn/b&n/abe/pwll) was just plain nuts. When I heard that Christiane Nüsslein-Volhard was coming out with a book, my interest and curiousity were definitely piqued. The work by Nüsslein-Volhard and Wieschaus has shaped my entire discipline, so I was eagerly anticipating what her new book,…
razib | July 19, 2006Over at Darwin Catholic there has been some discussion of the human influenced evolution of dogs. Seed actually has it right, it is human influenced evolution. Some of the interpretation of the paper which showed an increase in the frequency of 'deleterious' alleles spin the results as suggesting that dogs are beyond the constraints of evolution. But, as I pointed out over at DC's weblog dogs are evolved toward their own special adaptations, and the lack of these adaptations in their wild cousins is not evidence that wolves carry "deleterious" traits. For me, the most fascinating case of…
pharyngula | July 19, 2006How do you make a limb? Vertebrate limbs are classic models in organogenesis, and we know a fair bit about the molecular events involved. Limbs are induced at particular boundaries of axial Hox gene expression, and the first recognizable sign of their formation is the appearance of a thickened epithelial bump, the apical ectodermal ridge (AER). The AER is a signaling center that produces, in particular, a set of growth factors such as Fgf4 and Fgf8 that trigger the growth of the underlying tissue, causing the growing limb to protrude. In addition, there's another signaling center that forms…
clock | July 19, 2006Sometimes a metaphor used in science is useful for research but not so useful when it comes to popular perceptions. And sometimes even scientists come under the spell of the metaphor. One of those unfortunate two-faced metaphors is the metaphor of the Biological Clock.
First of all, there are at least three common meanings of the term - it is used to describe circadian rhythms, to describe the rate of sequence change in the DNA over geological time, and to describe the reaching of a certain age at which human fertility drops off ("my clock is ticking").
I prefer the Rube-Goldberg Machine…
razib | July 18, 2006While I'm engaged in a bit of "radio silence," check out RPM's blog, he's posting some good stuff.
Also, I have a short entry up on historical population genetics in the context of the British Isles at my ,other weblog.
razib | July 17, 2006A recent paper in Genome Research titled Relaxation of selective constraint on dog mitochondrial DNA following domestication concludes that domestication of wolves and their transformation into dogs were facilitated by relaxed selection and increased latent variation, from which subsequent selection could operate upon. Here is a good popular press summary. The basic finding is that domestic dogs in their sample (13 dogs, 6 wolves and 3 coyotes had their full mtDNA sequenced) exhibited greater accumulation of mildly deleterious mutations, in a nearly neutral fashion. Relaxation of selection…