Ezra Klein asks "How Quickly Do Genes Change?" in response to Andrew Sullivan gushing over Greg Clark's new book, A Farewell to Alms. Clark offers the hypothesis that the industrial revolution in England was catalyzed in part by changes in behavior which might have been reinforced by selection for particular alleles. In terms of the specific hypothesis, I'm skeptical and would probably bet that Clark has overplayed his hand and put too many eggs in one basket. But, in response to Ezra's question I threw down a flurry of comments (with a lot of grammatical errors due to my haste) which you can see over at the post. The short answer of course is: the rate of change of allele frequencies depends on the parameters. Molecular genetics is often about positing deterministic biophysical pathways, but evolutionary genetics is just as interested in the fluctuations and variations of alleles over time, and those variations are contingent on a host of factors. There isn't one specific answer, just a range depending on your assumptions or the empirical realities (e.g., selection coefficient, heritability of the character, demographic history, meta-population dynamics, etc.). So whether Clark's hypothesis is right or wrong as an empirical question, not a theoretical one. One can't rule it out a priori.

TNR has an interesting piece (here is a cache version of the first page) about Jewish-Christian polemics (in both directions). It is mostly a review of Peter Shaeffer's Jesus in the Talmud; a scholarly work which predictably appeals to anti-Semites. My comment on Noah Feldman and his perceptions of Orthodox Judaism elicited a lot of response. Most of it was interesting, though of course some individuals across the web became convinced that I was an anti-Semite who was a Muslim working against Jews. This missed the whole greater thrust of my point: it isn't always about you, context and situation are not only critical, but often they are determinative. In the TNR piece the author notes now anti-Christian invective was much more pronounced in the Babylonian Jewish literature than in the Palestinian equivalents. Is this because Babylonian Jews were naturally more anti-Christian than Palestinians? As a matter of fact the Palestinian Jews were under the rule of a Christian Empire which was just initiating a long history of focused anti-Jewish persecutions and forced conversions. In contrast, Babylonian Jews were numerically preponderant across broad swaths of southern Mesopotamia, and though under the rule of the Zoroastrian Sassanids, there was no great threat of being forcibly converted or oppressed for religious reasons. Rather, under the Sassanids both the Christians and the Jews were at parity, and Schaefer suggests apparently that Jews had an advantage, unlike Christians they had no notional affiliation with a foreign empire (Rome). I think the TNR piece has to be careful here, because it is important to remember that the Christians within the Sassanid Empire were generally of the Church of the East, whose intellectual and institutional origins were are sharp variance with both the Jacobite (anti-Imperial) sects across the border in Syria as well as the Chalcedonian orthodoxy promoted by Constantinople. There was a reason that these eastern groups were sometimes termed the Persian Church.

Hung with old college friends last night. We kept referring to South Park episodes to illustrate a point or make an analogy so as to clarify an issue. Interesting that this is a common touchstone for my generation.

Just How Hot Is That Red Hot Chili Pepper?.

Update: Another post on this topic at my other blog.

A few days ago I pointed to a new paper, Evidence of Still-Ongoing Convergence Evolution of the Lactase Persistence T_-13910 Alleles in Humans. Knowing my interest in the topic you might assume that I would be "all over this." Well, I finally read the paper (twice) and I have to say it's a really interesting piece of work.

To the left is a map of the proportion of the T_-13910 SNP near the LCT locus in selected populations. In Eurasia the correlation between this allele and "Lactase Persistence" (LP) is very strong (r ~ 0.97 in terms of LP phenotype and frequency of T_-13910 with a p of less than 0.001) . Functional studies have shown that the presence of T_-13910 results in the maintenance of transcription of the enzyme which breaks down lactose sugar in milk. The phenotype is interpreted in the "dominant/recessive" model, one copy of the allele is all that is needed to be in a state of LP. So, if a population has a 0.50 proportion of the LP conferring allele, via the Hardy-Weinberg Equilibrium we know that 75% of the population exhibits the LP phenotype. A close look at the map shows us a few things. First, the allele of interest is modal in northern Europe. That is, its frequency is the highest there. This is no surprise as LCT has some of the strongest signatures of selection within the genomes of Europeans studied so far (the longest "haplotype block"). But, do note that the LP conferring allele is found throughout western Eurasia, and even into into nothern Africa. Though it is most frequent in northern Europe, that does not necessarily mean that the T_-13910 arose there.

/. has a post with the title Humanity's Genetic Diversity on the Decline, drawing from a recent paper which found that the mtDNA haplotype diversity in England was lower than 1,000 years ago. The authors were surprised because of course one presumes England is more cosmopolitan today than in the past, and so there would be more diversity. As a resolution to their finds they suggest that demographic dynamics, such as the Black Death with resulted in the death of 1/2 of the English in 1 generation, as well as selection for mtDNA variants (i.e., a haplotype is linked toward some functional benefit which increases its frequency within the population). One might also note that England has gone through massive population growth, and this has not always been equitable. In other words, the demographic explosion of the last few centuries might have been biased toward particular regions or segments of the English population, and reproductive output might have varied a great deal more than the common poisson assumption.

The New York Times has an article up reiterating the fabled "bushiness" of hominid phylogenetic trees:

Scientists who dated and analyzed the specimens -- a 1.44 million-year-old Homo habilis and a 1.55 million-year-old Homo erectus -- said their findings challenged the conventional view that these species evolved one after the other. Instead, they apparently lived side by side in eastern Africa for almost half a million years.

My knowledge of bones is not strong, so I leave it to John Hawks or Kambiz to decompose the details. That being said, the big picture is that this is another strike against anagenesis for the human lineage, which basically is a scientific concept expressed in the famous t-shirts showing a progression from ape to ape-man to Neandertal to modern human. Anagenesis easily slots into human cognitive biases such as the "Chain of Being," and I don't know how revolutionary it is to bury it again for the thousandth time. All that being said, it is a little irritating to see this bit of pop-evolutionary thinking crop up near the end of the piece:

In High-wire Act:

Before agreeing to work on the opera, Albarn and Hewlett made two trips to China with Shi-Zheng. While visiting the city of Yinchuan, in Ninzxia Province, Albarn spent an afternoon lying on the floor of his hotel room recording the sound of horns in the street.

There is no "Ninzxia province." Yinchuan is the capital of Ningxia. Or Níngxià or Ning-hsia or Ningsia. Google turns out 5 results for "Ninzxia," one of which is the article in The New Yorker (the others look like purposeful hidden misspellings so that search engines will catch the sites).

Not a big deal, but if you are going to mock the errors of other publications you better be above reproach. And secondly, China is not some obscure country. It would be kind of embarrassing if a Chinese publiction misspelled North Dakota as "North Dakoto." Of course, that publication wouldn't be The New Yorker.

(this is in the print edition, so if they fix it online that'll always be there)

I mentioned earlier that Google News had kicked ScienceBlogs off their news feed, but left the Discovery Institute's blog. Well, look at what showed up today in my "Google Alerts" for the query "human evolution":

A few weeks ago the study about obesity being socially contagious was all the rage. For anyone interested in human behavior this shouldn't be surprising, we are a social creature and our peer group is an essential part of our 'extended phenotype'. The psychologist Judith Rich Harris has famously argued that the 40% of unattributed component of variation of personality is due to our peer groups (10% is parents and 50% is genes). In Harris' model the best thing that parents can do is choose a particular peer group with values which reflect their own priorities. In other words, buying a house in a "good community" with "good schools" is paramount. Your peers are the measure which you take into account and help shape your values, priorities, and goals in life. So with that, I was interested in a new study which tracks male twins and shows the importance of genetic variation in the choices which they later made in terms of assorting into distinct peer groups. From the conclusion: