Hope the weather is good enough where you are that you’ll enjoy the weekend.
Tories Still Short of a Majority: Hix-Vivyan Prediction up to 26 April. Trendlines + 95% confidence intervals as shading. What’s not to like?
Tolerance and Tension: Islam and Christianity in Sub-Saharan Africa. In 1900 there were 50% fewer Christians than Muslims in Africa. In 1950 there were as many Christians as Muslims in Sub-Saharan Africa. Today there are twice as many Christians as Muslims. Christ was a black man, while Muhammad had white thighs.
Listening to (and Saving) the World’s Languages. I don’t get why there are always “languages of the world are dying” articles popping up regularly in the mainstream and scientific media. I mean there’s a great benefit to having one language unify diverse groups. It’s just like how Europeans gained efficiencies by ditching their local currencies and going with the Euro. Eh, well, perhaps not the best example right now….
What can you learn from a whole genome sequence? Dr. Daniel MacArthur seems to suggest that there isn’t a whole lot more you can learn that you couldn’t learn from a chip with hundreds of thousands of SNPs instead of all 3 billion base pairs. Seems about right. And remember the baseline, many people are highly skeptical of the marginal value of the SNP chips beyond what you’d know from your family history.
Absence of Evidence for MHC–Dependent Mate Selection within HapMap Populations. I’m starting to lean away from thinking that the MHC studies in humans are finding any real robust correlations. The studies are literally all over the place, with reverse signs of statistically significant correlations in some cases.
Below I stated:
…until the late 20th century the majority of the ancestry of the white population of the republic descended from those who were counted in the 1790 census.
A commenter questioned the assertion. The commenter was right to question it. My source was a 1992 paper that estimated that only in 1990 did the proportion of American ancestry which derived from those who arrived after the 1790 census exceeding 50%. In other words, if you ran the ancestors of all Americans back to 1790, a majority of that set would have been counted in the 1790 census (so people of mixed ancestry would contribute to the two components are weighted by their ancestry).
I am currently reading Peter Heather’s Empires and Barbarians: The Fall of Rome and the Birth of Europe. This is a substantially more hefty volume in terms of density than The Fall of the Roman Empire: A New History of Rome and the Barbarians . It is also somewhat of a page turner. One aspect of Heather’s argument so far is his attempt to navigate a path between the historically tinged fantasy of what its critics label the “Grand Narrative” of mass migration of barbarian tribes such as the Goths, Vandals and Saxons during the 4th to 6th centuries, dominant before World War II, and its post-World World II counterpoint. As a reaction against this idea archaeologists have taken to a model of pots-not-people, whereby cultural forms flow between populations, and identities are fluid and often created de novo. This model would suggest that only a tiny core cadre of “German” “barbarians” (and yes, often in this area of scholarship the most banal terms are problematized and placed in quotations!) entered the Roman Empire, and the development of a Frankish ruling class in the former Gaul, for example, was a process whereby Romans assimilated to the Germanic identity (with the shift from togas to trousers being the most widespread obvious illustration of Germanization of norms). I believe that liberally applied this model is fantasy as well. Being a weblog where genetics is important, my skepticism of both extreme scenarios is rooted in new scientific data.
A few months ago I blogged a paper in PLoS Biology which suggested that a common Y chromosomal haplogroup, in fact the most common in Europe and at modal frequency along the Atlantic fringe, is not pre-Neolithic. Rather their analysis of the data implied that the European variants were derived from an Anatolian variant. The implication was that a haplogroup which had previously been diagnostic of “Paleolithicness,” so to speak, of a particular population may in fact be an indication of the proportion of Neolithic Middle Eastern ancestry. The most interesting case were the Basques, who have a high frequency of this haplogroup, and are often conceived of as “ur-Europeans,” Paleolithic descendants of the Cro-Magnons in the most romantic tellings. I was somewhat primed to accept this finding because of confusing results from ancient DNA extraction which implies a lot of turnover in maternal lineages, the mtDNA. My logic being that if the mtDNA exhibited rupture, then the Y lineages should too, as demographic revolutions are more likely to occur among men.
But perhaps not. A new paper in PLoS ONE takes full aim at the paper I blogged above. It is in short a purported refutation of the main finding of the previous paper, and a reinstatement of what had been the orthodoxy (note the citations to previous papers). A Comparison of Y-Chromosome Variation in Sardinia and Anatolia Is More Consistent with Cultural Rather than Demic Diffusion of Agriculture:
OECD’s Gurría mourns death of economist Angus Maddison. I highly recommend his books such as Contours of the World Economy 1-2030 AD. I would concede that the data would sometimes be sketchy or fragmentary, but when it comes to historical models there’s a lot more jabber than legwork. It is notable how much the jabberers have citations to Maddison’s research.
Experiments in cultural transmission and human cultural evolution. I’ve read plenty of models of cultural evolution (Cavalli-Sforza & Feldman, Boyd & Richerson, come to mind), but a post which reviews some more empirical literature. One criticism of modelers of cultural evolution is that they’re all talk, no action, and so basically just mathed up versions of armchair humanists.
Wired for Sex. The existence of two sexes is of obvious evolutionary genetic interest; males are an “expensive” cost for a lineage. But obviously there are other angles to explore, including neurological. Because sexual dimorphism takes a while to evolve I think one possible way to get a good grip on sex differences in the brain might be to look at male vs. female anatomy, function and neuochemistry across the great apes + humans. Presumably many of the differences are basal characteristics.
Psychopaths and Rational Morality. Would Mr. Spock have been a psychopath?
The Arc of Evolution Is Long and Rarely Bends Towards Advantageous Alleles: Why Does Popular Science Ignore Neutral Theory? Love the title. I think writing a book like “Climbing Mount Improbable” is going to be easier than writing “Probably Random Walking All Over.”
Can’t Pivot to the Economy With Magic. I disagree. It’s a world filled with magic & mystery, we need to just open our eyes and appreciate it. We can can use magic & mystery as fuel to generate productivity gains. A wizard in every home I say!
For those of you familiar with the formal mathematical models of cultural evolution (Cavalli-Sforza & Feldman, 1981; Boyd & Richerson, 1985), you’ll know there is a substantive body of literature behind the process of cultural transmission. In this respect, we have a great deal of theoretical knowledge regarding the three vectors of transmission: vertical, oblique and horizontal. We also know about the myriad of ways in which individuals may copy one another: via their parents or peers; conformist transmission (copying the most popular variant) or anti-conformist; randomly selecting someone to copy; and copying cultural traits produced by the most prestigious individuals within a group. Complicating the situation even more are social learning mechanisms: emulation, imitation, explicit teaching, and language. In addition to this, models have addressed when cultural transmission is preferable to individual learning and/or genetic evolution, with the general conclusion being: “that cultural transmission should be favoured when (i) environments change too rapidly for genes to track them effectively, but not so rapidly that the behaviour of a potential model becomes outdated, and/or (ii) individual learning is particularly costly or difficult” (Mesoudi & Whiten, 2008, my emphasis).
Keeping in mind all of these factors, it comes as a surprise that experiments into cultural transmission are lacking. If we look at evolutionary biology, then there are many experiments into small-scale microevolutionary processes, such as natural selection, sexual selection, mutation and drift, which are then applied in showing how these processes generate population-level, macroevolutionary patterns. It follows then, that this sort of population-level thinking can be applied to cultural evolution: the forces and biases of cultural transmission can be studied experimentally to see if they fit with population-level patterns of cultural change documented by scientists. As the current paper by Mesoudi & Whiten (2008) notes, this potentially gives cultural transmission experiments added significance: “cultural transmission should not only be studied for its own sake (i.e. in order to better understand cultural transmission itself), but also in order to explain broader cultural patterns and trends, all as part of a unified science of cultural evolution”.
Indeed, lab experiments into cultural transmission are growing in popularity. I think this is important because these experiments not only add to the insights revealed by mathematical modelling, theoretical literature and real-world data, they also provide alternative explanations for the observed patterns and idiosyncrasies of human behaviour. The current paper provides a nice overview of the literature and methodology used to study “some kind of transmission of information (knowledge or behaviour) along a chain or within a group of more than two participants”. Specifically, they focus on three experimental paradigms: the linear transmission chain, the replacement model and the closed-group method.
Dr. Daniel MacArthur pointed me to this story, Conn. woman alleges genetic discrimination at work:
A Connecticut woman who had a voluntary double mastectomy after genetic testing is alleging her employer eliminated her job after learning she carried a gene implicated in breast cancer.
Pamela Fink, 39, of Fairfield said in discrimination complaints that her bosses at natural gas and electric supplier MXenergy gave her glowing evaluations for years, but targeted, demoted and eventually dismissed her when she told them of the genetic test results.
Her complaints, filed Tuesday with the U.S. Equal Opportunity Commission and Connecticut Commission on Human Rights and Opportunities, are among the first known to be filed nationwide based on the federal Genetic Information Nondiscrimination Act.
What probability do readers put in regards to this being a legitimate complaint? This seems a large firm, so I doubt that group insurance rates would change because of one person (I have heard of this occurring in small businesses where an expensive employee or employee’s family member can effect the rate for everyone else). So if it is legitimate the main issue would have been their fear of future illness, but the woman in question went through a double mastectomy, which I assume would obviate that concern. What am I missing? Are there expectations that she’d be taking medical leave in the future due to follow up operations or treatment?
Update: Brendan Maher has some follow up from Fink’s lawyer.
Change is quite in the air today, whether it be climate change or human induced habitat shifts. What’s a species in the wild to do? Biologists naturally worry about loss of biodiversity a great deal, and many non-biologist humans rather high up on Maslow’s hierarchy of needs also care. And yet species loss, or the threat of extinction, seems too often to impinge upon public consciousness in a coarse categorical sense. For example the EPA classifications such as “threatened” or “endangered.” There are also vague general warnings or forebodings; warmer temperatures leading to mass extinctions as species can not track their optimal ecology and the like. And these warnings seem to err on the side of caution, as if populations of organisms are incapable of adapting, and all species are as particular as the panda.
That’s why I pointed to a recent paper in PLoS Biology, Adaptation, Plasticity, and Extinction in a Changing Environment: Towards a Predictive Theory below. I am somewhat familiar with one of the authors, Russell Lande, and his work in quantitative and ecological genetics, as well as population biology. I was also happy to note that the formal model here is rather spare, perhaps a nod to the lack of current abstraction in this particular area. Why start complex when you can start simple? Here’s their abstract:
Many species are experiencing sustained environmental change mainly due to human activities. The unusual rate and extent of anthropogenic alterations of the environment may exceed the capacity of developmental, genetic, and demographic mechanisms that populations have evolved to deal with environmental change. To begin to understand the limits to population persistence, we present a simple evolutionary model for the critical rate of environmental change beyond which a population must decline and go extinct. We use this model to highlight the major determinants of extinction risk in a changing environment, and identify research needs for improved predictions based on projected changes in environmental variables. Two key parameters relating the environment to population biology have not yet received sufficient attention. Phenotypic plasticity, the direct influence of environment on the development of individual phenotypes, is increasingly considered an important component of phenotypic change in the wild and should be incorporated in models of population persistence. Environmental sensitivity of selection, the change in the optimum phenotype with the environment, still crucially needs empirical assessment. We use environmental tolerance curves and other examples of ecological and evolutionary responses to climate change to illustrate how these mechanistic approaches can be developed for predictive purposes.