John Hawks has a long interesting post on the possible phylogeographic impact of Ice Ages and Interglacials upon Neandertal demographics. I believe John had earlier posited that worldwide variations in long effective population size might generate the differences in genetic diversity across modern human populations.

If I were to add 5 cognitive science journals and 5 history journals to my RSS/reading list, which ones would they be? The only cognitive science journal I’m familiar with is Cognition.

Hsien Hsien Lei reports on an interview in the May/June issue of Stanford Magazine with L.L. Cavalli-Sforza:

…A major genetic change which started already some centuries ago, with the navigation of the oceans, and is becoming faster now, is globalization. This is having major genetic consequences. It will bring back greater unity of the species, by diluting and eventually canceling differences among ethnic groups existing today, that are largely if not exclusively the consequence of adaptation to environments that differ most climatically to which modern humans spread in the last 50,000 years….

One of the novel insights of the field of human genomics is that universal selection pressures have resulted in alternative genetic responses to converge upon the same phenotype. For example, the light skin of East Asians & Europeans are independent derivations from the darker skinned ancestral type, and the genetic architecture of the trait attests to this. Now, the extent of intergroup admixture today is actually very modest, after all, very little European specific genetic material is entering the populations of China or South Korea! Nevertheless, in places like the United States widespread admixture between Europeans & East Asians is occurring, so you have the confluence (collision?) of genetic architectures which emerged in parallel meeting their “other half” for the first time. Since East Asians and Europeans have already been subject to sweeps which moved them (presumably) to their phenotypic optimum the selective value of the introduced alleles is probably not that high. On the other hand, pleiotropy implies that many loci have myriad side effects, and one never knows what can happen when you jump from one genetic background to another (good or bad). Since many of the alleles which differentiate East Asians from Europeans that evolved in parallel are the result of relatively recent sweeps I doubt they’re embedded in essential contingent coadapted gene complexes, so I would be surprised by widespread negative or positive fitness effects because of statistical epistasis.

The reason I’m focusing on alleles with selective value is that moments like the settlement of the Americas by a small group of Iberian men and the generation of a mestizo population within a century through hybridization are rare events. If random-mating forces are what we depend on to eliminate between group variation I think we’ll be waiting a long, long, time, because people tend combine in pairs of likes. It might only take one migrant per generation between demes to keep them from wandering off into alternative genetic directions (the larger the population the smaller the between generation sampling variance, while the smaller the population the bigger impact that one migrant can have on the gene pool), but many demes haven’t had that much migration for a long, long, time. In contrast to a focus on neutral loci and total genome content, Loren Rieseberg’s work has suggested that the spread of high advantageous alleles can maintain species continuity and coherency.

Related: 10 questiosn for L.L. Cavalli-Sforza.

In the comments the unicorn-riding TGGP says:

When I was religious I didn’t have a problem with evolution, because my idea of God was omniscient enough to arrange a deterministic universe in such a manner so as to produce the results He wanted without having to get up off His Holy Couch very often to get stuff done. I suppose it doesn’t make much sense for an omnipotent God to be so lazy, but that’s just what I figured I would do in His position.

Though theists in the Abrahamic tradition do generally avow a belief in god who is omniscient & omnipotent (among other characteristics), outside of the constraints of time & space, psychological & anthropological research tends to converge upon the consensus that the human working cognitive conceptualization of “god” doesn’t include these traits. Unscripted narrations where god is integrated into human affairs always imply a model of the deity bounded by time & space & partaking of the same banal universe as believers, though exhibiting powers and perceptions of far greater magnitude than that of mortals.1 This makes sense when one considers that the human mind itself has constraints in terms of how it can model the universe, and a god which transcends the universe is simply beyond gestalt comprehension. An analogy might be that one can believe in higher spatial dimensions than the three we perceive as a matter of logic, but a intuitive conceptualization of higher dimensionality spaces is beyond the grasp of the human mind.2

In any case, the cognitive reality that humans have in their mind the concept of a limited god, despite their sincere professions of belief in a transcendent one, seems to make theistic evolution somewhat more understandable as a natural response to the facts of the universe.3 If the implicit internal models of gods have within them constraints imposed by natural processes then a deity who utilizes such processes easily drops out of the chain of inferences. This does not speak to the theological plausibility of such a god (i.e., working from first principles in regards to the nature of god as a being with traits x, y, z, etc.), but human beliefs and thoughts are not internally consistent.

1 – Participants in the studies of which I’m referring to are prompted to generate novel stories where the gods in which they believe in operate upon the universe over which they have dominion. Working backward from the characteristics of these stories, that is, working up the chain of implied inferences invariably leads researchers to conclude that the conceptualization of the god within these narrations contradicts an omniscient & omnipotent being outside of the universe. This model is consistent to the cross-cultural universality of particular times, places and objects being propitious and sacred to the gods, even though said gods are often notionally unbounded from time & space.

2 -To be clear, the anthropomorphic gods of yore remain ascendant within the human cognitive substrate, no matter the historical fact of their intellectual defeat at the hands of philosophical theism. Humans now believe in the god of the philosophers, but they imagine the god of the ancestors. I contend that many of the “paradoxical” behaviors of theists in response to tragedies or successes and the character of their relationship with the gods whom they avow to believe in can be explained by this “double truth,” the disjunction between the philosophical & the cognitive deity.

3 – This does not speak to the validity of theological arguments for theistic evolution, rather, it only suggests that the reason the concept might “make sense” to a large number of theists is because follows from their implicit god-concept.

Obviously a sex-linked trait. All males seem to exhibit the trait but none of the females. It can’t just be the lack of something on the X, otherwise some of the females would have exhibited this trait as well. No, perhaps a mutant on the Y which acts in a trans & “dominant” acting manner to repress or abolish something on other chromosomes?

Note: All the males exhibit the phenotype, but none of the females do. If you accept it is a sex-linked trait which manifests because the males don’t have a compensatory copy of the allele inherited from the mother, then all their mothers had to have at least one copy of the “bad” allele. That means that random mating implies that at least 1/4 of the women in the current generation would exhibit the trait (assume that all the mothers are heterozygous), as they would inherit a “bad” copy from both parents. If all the males exhibit the trait, but none of the females do, that would imply something that acts dominantly from the Y chromosome, which only males have.

I was at the local food co-op when I saw Brother Bru Bru’s African Hot Sauce. It said it was “very hot!” on the label, and since some of you had recommended African hot sauces to me earlier I decided to check it out. The label suggests that there were assorted peppers mixed into this concoction. Frankly, for me it was a bit on the mild side. Also, the background sweetness and pungency overwhelmed the heat. Nevertheless, I enjoyed the flavor, even if I was disappointed by tepid spice level. I’m giving it a 4 out of 10, mostly because this was way too mild for a “very hot!” sauce. I mean, the label advertises that it is peddling indigenous wisdom, and the cover has a bug-eyed black guy wearing a tribal necklace. It would have had to be real good to make up for the promises & kind of offensive marketing package, and it just didn’t step up.

Here is a report on some developments on the hypothesis that humans are very well evolved to run in the heat. A physical anthropologist told me that while cold adapted peoples can acclimate to tropical conditions, heat adapted peoples are not as good at the reverse. That suggested to me that as a tropical species we have deep and extremely powerful adaptations which allow us to tolerate heat, and these adaptations might have other uses that remained advantageous once we moved north into Eurasia.

Just out in PLOS Genetics, Localizing recent adaptive evolution in the human genome. This has been accepted, but not reedited. Here’s part of the abstract:

Within these regions, genes of biological interest include genes in pigmentation pathways, components of the dystrophin protein complex, clusters of olfactory receptors, genes involved in nervous system development and function, immune system genes, and heat shock genes. We also observe consistent evidence of selective sweeps in centromeric regions. In general we find that recent adaptation is strikingly pervasive in the human genome, with as much as 10% of the genome affected by linkage to a selective sweep.

If you read the paper you’ll note that they claim to be able to detect sweeps near fixation.

More genes underwent positive selection in chimpanzee evolution than in human evolution is on PNAS‘ site now….

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