razib | September 3, 2007Curious about height? Check out this new paper in Nature Genetics, A common variant of HMGA2 is associated with adult and childhood height in the general population. Nature News has a nice report for public consumption.
Last week when I posted about heritable traits I used height as an illustrative example. The reasoning was pretty simple, it's a rather concrete phenotype which most humans have an intuitive grasp of in terms of the range of variation, and it also happens to exhibit high heritability in developed populations; on the order of 0.90, i.e., 90% of the variation in the…
razib | September 2, 2007I used the bathroom at Minneapolis International today. Nothing weird that I noticed, but perhaps I wasn't looking closely enough.
razib | August 30, 2007When someone tells you that height is 80% heritable, does that mean:
a) 80% of the reason you are the height you are is due to genes
b) 80% of the variation within the population on the trait of height is due to variation of the genes
The answer is of course b. Unfortunately in the 5 years I've been blogging the conception of heritability has been rather difficult to get across, and I regularly have to browbeat readers who conflate the term with a. That is, they assume that if I say that a trait is mostly heritable I mean that its development is mostly a function of genes. In reality not…
razib | August 29, 2007I've talked about menopause a fair amount on this blog, usually in relation to the Grandmother Hypothesis. So I thought I'd pass along this article, Eusociality, menopause and information in matrilineal whales, along. I know that many think that menopause is something that will naturally happen if a mammal lives long enough, as opposed to being an adaptation. I'm generally skeptical of this. The one physical anthropologist who I've talked to and who has explored the topic kept reiterating to me how contingent and interlocking the physiological cascades which shut down the reproductive…
razib | August 29, 2007Update: Comment from Chris Surridge of PLOS One:
Just a quick note. The paper is now formally published on PLoS ONE. The citation is:
Tuljapurkar SD, Puleston CO, Gurven MD (2007) Why Men Matter: Mating Patterns Drive Evolution of Human Lifespan. PLoS ONE 2(8): e785. doi:10.1371/journal.pone.0000785
As it is PLoS ONE you can rate the paper, annotate and discuss it there too.
There's a new preprint posted (PDF) on PLOS One titled Why Men Matter: Mating Patterns Drive Evolution of Human Lifespan. The basic question is this: why do humans live beyond the lifespan of the post-menopausal female…
razib | August 28, 2007Genetic and environmental contributions to prosocial behaviour in 2- to 9-year-old South Korean twins:
...The best-fitting model indicated that 55%...of the variance in the 2- to 9-year-olds' prosocial behaviour was due to genetic factors and 45%...was due to non-shared environmental factors. It is concluded that genetic and environmental influences on prosocial behaviour in young South Koreans are mostly similar to those in western samples.
This is the "standard" finding, most of the variation in behavior is due to genes or non-shared environment. In The Nurture Assumption Judith Rich…
razib | August 28, 2007I was talking with a friend of mine who is an economist about science, and the great productivity in modern societies which allows for the perpetuation of narrow specialties in scholarship. I repeated to him my own hunch that if all scientists who were alive today disappeared and the next generation of aspiring scholars had only books and other instructional materials to go on, science would simply disappear as an enterprise. The point I was trying to get across is that scientific ideas are contingent upon a particular cultural framework. That is, science is a culture. And that culture is…
razib | August 28, 2007Over at my other blog Herrick posts a response to 10 questions for Gregory Clark. Clark is an economic historian whose most recent book Farwell to Alms is making a splash. I read the book recently, but because I'm not well versed in economics I've held off saying much. I will add that Clark's point that the typical humans of 1800 were poorer and less well off than those of 10,000 BCE is an important insight, and it is born out by decades of analysis of remains which show that farmers are on average underfed and nutrient deprived vis-a-vis hunter-gatherers.
razib | August 25, 2007Check out this new interview with Steven Pinker. It ostensibly focuses on his new book, The Stuff of Thought, though it covers a lot of ground. My own feeling is that the interviewer should have let the focus be more on Pinker than his own pet theories, but there's a lot of good stuff in there.
razib | August 25, 2007Yesterday I posted on the resurrection of the "redheads going extinct" meme (as I noted, this story seems to cycle every few years). The current source is National Geographic Magazine, which doesn't have the "article" online. I went to the bookstore and checked out the September 2007 issue, and a write up does exist about the redheads going extinct. Unlike the secondary sources it isn't as sensationalist, and makes more than a passing nod to the Hardy-Weinberg logic from which the inference is derived.
That being said, the write up in National Geographic Magazine simply recycles older…
razib | August 25, 2007Check it, Chris Mooney is on bloggingheads.tv. He's promoting his book Storm World, which is a really good read. I can't speak in detail to the area of science which Chris covers, but the bigger picture issue of the "intersection" between public policy and the culture of science and the ensuing controversies have a universal resonance.
razib | August 25, 2007p-ter points me to a new paper which documents interspecies hybridization in monkeys whose lineages putatively diverged about 3 million years ago. Note that the hybridization follows Haldane's rule: the heterogametic sex (in mammals the males) exhibits sterility while the other sex does not. Whatever genetic incompatibilities built over the period during which the two populations became distinct the less robust sex (males have only one copy of the X chromosome, ergo, sex-linked diseases) naturally exhibits greater breakdown in hybrids. In any case, the story is obviously relevant to…
razib | August 24, 2007Every few years it seems that a new meme declares that "blondes will go extinct!" or that "red hair will go extinct!" I've only been blogging for 5 years, and this story has already cycled multiple times. A co-blogger of mine told me that he did some digging and it seems that this meme is of old vintage, with "blondes going extinct!" stories dating back to the 19th century. The current craze (as evidenced by blogs) seems to have started at an Australian newspaper. But, it is sourced originally to National Geographic Magazine.
First, the story doesn't appear on National Geographic Magazine…
razib | August 24, 2007RPM pointed me to this new paper, Major Histocompatibility Complex Heterozygosity Reduces Fitness in Experimentally Infected Mice:
...Our results show that MHC effects are not masked on an outbred genetic background, and that MHC heterozygosity provides no immunological benefits when resistance is recessive, and can actually reduce fitness. These findings challenge the HA hypothesis and emphasize the need for studies on wild, genetically diverse species.
MHC are a group of loci which are critical in the adaptive immune systems of "higher" organisms. They are also among the most polymorphic…
razib | August 22, 2007This is more of a quick note than a post. In Africa (and to a lesser extent other regions) the rise of malaria has resulted in an extreme evolutionary response, basically the heterozygote is extremely fit vis-a-vis mutant homozygotes (which exhibit Sickle Cell Anemia) and the wild type homozygotes. This is a case of balancing selection via overdominance, the frequencies of the alleles are determined by the fitness of the three genotypes (mutant homozygote, heterozygote and wild type homozygote). Naturally polymorphism will be maintained since the heterozygote by necessity needs the…
razib | August 21, 2007This morning in NYC I took a cab to Penn Station. It was raining really hard...so I was curious, I asked the cab driver, "So do you get more fares when it's raining?" He explained that yes, there are more fares on hand, but because of the rain and traffic jams it works out to less revenue in a given day (e.g., he explained that half the time he's stuck in traffic without a fare).
Then I showed up in D.C. this afternoon, and I notice no meter or even all that offical crap that NYC cabs have. I start freaking out and wondering whether this is really a cab, but the guy drops me off and asks…