Since I’ve moved to Unz Review I’ve attracted a set of readers who are used to the level of discourse on topics evolutionary which is the norm on “HBD blogs.” Let me be clear that I don’t tolerate uninformed speculation because I don’t care to listen to it as I don’t gain any value from it. This is in response to a long and bizarre hectoring rant about my lack of credentials, the nature of heredity, etc. It reminded me of the moron who accused me of not understanding Lewontin’s Fallacy at Inducivist a few years ago (a further idiot also decided to “explain” epistasis to me). A buzz word or two does not sagacity make. Naturally this person was banned. But in any case this is as good a place as any to suggest that someone who wants to engage with me in a manner where I will take them seriously should be at least somewhat familiar with population genetics, and hopefully genomics. This naturally curtails communication with most of the human race, and that’s the point. I will at some point die in the future unless the Singularity arrives, so I do not wish to waste my time talking to most of the human race about things they know nothing of.

With the pleasantries out of the way I am here to offer a way to meet the threshold of knowledge which will make you fluent in leaving comments here.

– You can read Principles of Population Genetics.

– Read the UConn population genetics notes.

– Read Graham Coop’s population genetics notes.

– Read Joe Felsenstein’s population genetics text.

All of these are pretty easy, and three of them are free. You don’t need to derive all the formalisms. God knows I haven’t. But you need a basic algebraic framework to think about the process quantitatively. Additionally, it is probably useful to get at least some genomics background since that’s the empirical data that is really relevant for much of the commentary on this weblog.

I hope I’m clear that any rude, annoying, and hectoring comments are going to result in immediate banning.

I am an author on this paper, Comparative analysis of the domestic cat genome reveals genetic signatures underlying feline biology and domestication:

We present highlights of the first complete domestic cat reference genome, to our knowledge. We provide evolutionary assessments of the feline protein-coding genome, population genetic discoveries surrounding domestication, and a resource of domestic cat genetic variants. These analyses span broadly, from carnivore adaptations for hunting behavior to comparative odorant and chemical detection abilities between cats and dogs. We describe how segregating genetic variation in pigmentation phenotypes has reached fixation within a single breed, and also highlight the genomic differences between domestic cats and wildcats. Specifically, the signatures of selection in the domestic cat genome are linked to genes associated with gene knockout models affecting memory, fear-conditioning behavior, and stimulus-reward learning, and potentially point to the processes by which cats became domesticated.

I’ll have more to say, but here is a write up in Science. Super happy be part of the team that got this published, especially Mike Montague, who did the heavy lifting.

Early last year an ancient genomics paper came out with the title Derived immune and ancestral pigmentation alleles in a 7,000-year-old Mesolithic European. The point here is that light pigmentation associated alleles common in Europeans seem to be relatively new derived mutations from the ancestral state, associated with Africans. An Ewen Callaway write up highlighted the fact that one of the inferences made from these genomes is that these hunter-gatherers had light eyes (blue) and dark(er) skin. At the time I pointed out to Callaway on Twitter that we need to be careful here, as ancient Europeans may have had different variants, and these traits are not monogenic but exhibit dependencies on multiple loci. In light of my post below Graham Coop suggested a similar issue, that there could have been convergence. In other words, just because modern Europeans have particular derived alleles which confer a particular trait, it does not entail that ancient peoples who lived in Europe had to have the same alleles to confer the same phenotype. Alicia Martin observed that OCA2 is a locus where fast evolution occurred in both East Asians and West Eurasians (especially Europeans), but at different SNPs. In other words, the same gene is modified, but the mutational event is distinct.

Pigmentation in humans seems to be a trait we have a pretty good grasp of. Because most of the genetic variation between populations seems to be localized at relatively large effect loci GWAS has been good at picking up the signals. Tests of selection which look at haplotype structure also detect these loci because many of them seem to have swept up in frequency relatively recently. This is consonant with what ancient DNA is telling us, as a substantial proportion of modern European ancestry does derive from peoples who have been resident at high latitudes for tens of thousands of years, but new variants, possibly from the Middle East or elsewhere, have increased in frequency within this admixed populations (in South Asia the same pattern is evident, as the Ancestral North Indians likely introduced West Eurasian variants into the hybrid daughter populations).

But let’s think through some of the implications of the alternative scenarios. One model is implicitly the dominant one, that the modern skin lightening alleles which are derived in contemporary populations are due to new pressures for de-pigmentation. Though some de-pigmentation likely occurred early on, perhaps even in Neandertals, the full suite is recent. Another model is that there were other variants segregating in the older populations, and that new populations brought new variants which swept to fixation. My question is simple: if the indigenous populations of Europe were already relatively light skinned whey did the new alleles rise in frequency so rapidly?

Let’s unpack what I’m getting at. OCA2 and SLC24A5 are two loci implicated in de-pigmentation in Europeans. The regions around the selective events are highly homogenized so that there’s a long haplotype around them. This means that the causal variant was targeted by such strong selection that the flanking regions of the genome were swept upward in frequency faster than recombination could break apart the association.  SLC24A5 in particular seems to have been under very strong selection, to the point where almost all variation has been purged from European populations at this locus. In India SLC24A5 is also at a higher frequency than might be predicted by simple contribution of ANI ancestry. The issue that I’m getting at, assuming that modern continental populations such as Europeans are admixed, is why these skin lightening alleles swept to frequency so rapidly and in the case of SLC24A5 nearly to fixation. It’s framed by the analysis presented by this paper, Parallel Adaptation: One or Many Waves of Advance of an Advantageous Allele?:

Models for detecting the effect of adaptation on population genomic diversity are often predicated on a single newly arisen mutation sweeping rapidly to fixation. However, a population can also adapt to a new environment by multiple mutations of similar phenotypic effect that arise in parallel, at the same locus or different loci. These mutations can each quickly reach intermediate frequency, preventing any single one from rapidly sweeping to fixation globally, leading to a “soft” sweep in the population. Here we study various models of parallel mutation in a continuous, geographically spread population adapting to a global selection pressure. The slow geographic spread of a selected allele due to limited dispersal can allow other selected alleles to arise and start to spread elsewhere in the species range. When these different selected alleles meet, their spread can slow dramatically and so initially form a geographic patchwork, a random tessellation, which could be mistaken for a signal of local adaptation. This spatial tessellation will dissipate over time due to mixing by migration, leaving a set of partial sweeps within the global population. We show that the spatial tessellation initially formed by mutational types is closely connected to Poisson process models of crystallization, which we extend. We find that the probability of parallel mutation and the spatial scale on which parallel mutation occurs are captured by a single compound parameter, a characteristic length, which reflects the expected distance a spreading allele travels before it encounters a different spreading allele. This characteristic length depends on the mutation rate, the dispersal parameter, the effective local density of individuals, and to a much lesser extent the strength of selection. While our knowledge of these parameters is poor, we argue that even in widely dispersing species, such parallel geographic sweeps may be surprisingly common. Thus, we predict that as more data become available, many more examples of intraspecies parallel adaptation will be uncovered.

Basically, if the ancient North Eurasian populations had lighter skin due to their own alleles, why are the new light skin alleles sweeping up in frequency so strongly after admixture? (for Europeans, I’m thinking SLC45A2 and SLC24A5 in particular). Perhaps the selective sweeps were not driven by light skin at all? Or, perhaps the ancient North Eurasians didn’t have their own variants.

Addendum: The 2007 Neandertal red hair paper offers up a possible solution toward phenotype reconstruction: test the ancient genetic variants in cell lines to check for expression.

There’s another paper in Science which I don’t have much intelligent to say about, but which I want to point to because it seems really cool, Phylogenomics resolves the timing and pattern of insect evolution. Earlier work in phylogenetics tended to use a few characters or genetic markers. As noted in the abstract they used nearly 1,500 protein coding genes to construct this phylogeny. Some of my friends who know particular organisms have objected to specific branching patterns near the tips, but what I’d like to emphasize is how ancient insect lineages seem to be. Our own mammalian branch of the tree of life really only diversified over the last ~100 million years or so. Most of the big groups of insects had already started to coalesce by 300 million years ago! As far as land animals goes, insects are incredibly diverse and ancient. Near the end of the paper they state: “The almost linear increase in interordinal insect diversity suggests that the process of diversification of extant insects may not have been severely affected by the Permian and Cretaceous biodiversity crises.” There will always be insects….

As you may know the actress Daryl Hannah depicted Ayla, the protagonist from Jean Auel’s Clan of the Cave Bear, in the film version. Unlike many castings Hannah was an inspired choice, as she does look like the description of Ayla in the novels. Tall, blonde, and with a high forehead (remember, there’s a lot of contrast with Neandertals in these books). Auel depicts human Neandertal interactions to such an extent that there is hybridization. In the 1980s when her series first gained traction this was not particularly a popular angle. This was the age of “mitochondrial Eve”, when replacement was a more fashionable idea (ask Milford Wolpoff about it). Even though in the details Auel may have been wrong about hwo this process played out (admixture seems to have occurred earlier on in the modern human migration out of Africa, not in northern Eurasia), overall she has admitted feeling vindicated by the work of people like Svante Paabo.

But there’s one area that is pretty important where Auel was wrong: it seems that during the Ice Age anatomically modern European humans did not fit the Nordic ideal of tall, blonde, and gracile. One reason I posted the image of the skull of K14 in the post below is that even without professional background in analysis of skeletal morphology it is visually obvious that this individual was rather robust. There’s a reason that it was apparently termed “Australoid” by earlier anthropologists. The native people of Australia and Papua are among the most robust humans alive today. In contrast other populations have gone through a great deal of gracilization, especially over the last 10,000 years. What about the coloring? I couldn’t find a reference in Seguin-Orlando et al. to any analysis of the functions of the genome, but in Anne Gibbons’ piece in Science she states that K14 was ” a short, dark-skinned, dark-eyed man.” I doubt she would say this unless she knew from the research team what the genotype of this individual was. Perhaps there is a later paper coming out on population genomics rather than phylogenomics, but these results would be consistent with other results.

One story that ancient DNA is unraveling is that of the complexity of human demographic history. There are lots of surprises in store. But a second no less important angle is that humans have adapted and changed functionally over the last 100,000 years, to the point where salient physical traits vary a great deal across both time and space.

The above is a plot of shared drift (ergo, history) between Mal’ta, the 24,000 year old Siberian boy, and various world populations. As per Lazaridis et al. you see a north to south gradient in Europe. As per Raghavan et al. you see the evidence of a lot of contribution to Native American ancestry. The rest of the world tells an interesting story. Recall that the highest fraction of Ancestral North Eurasia (ANE) outside of the New World is among the peoples of the North Caucasus. Their shared drift statistic is depressed in comparison to Europeans because of their high fraction of Basal Eurasians (BEu). What I want you to focus on is a secondary mode of shared drift in northwest South Asia. The reddish tinged circle are the Kalash I am rather sure from what I have heard/seen. The Ancestral North Indian (ANI) ancestors of South Asians seem to resemble the people of the South Caucasus (Georgians/Armenians) from what I have read/seen (I’ve run a few f-stats and D-stats myself). If this means that have a fair share of BEu then their yellowish shading might be misleading in terms of their total ANE ancestry.

Just something to think about.

Addendum: Everything I’ve seen suggests that there were two movements into South Asia from the north/west. The Brahui/Baloch are very distinctive in comparison to the Kalash/Pathan/Burusho. This might be a function of continuous gene flow from distinct regions to the west as well, especially in the case of the Brahui/Baloch, who have had associations as far afield as Oman due to their geographic proximity.

Were Scandinavians the original people of Europe? Such a headline is very suggestive of a press release gone wrong. But no, you just need to see what Eske Willerslev actually said to see the source of the headline. It was his lab which published the recent paper in Science, Genomic structure in Europeans dating back at least 36,200 years. Willerslev states:

”Genetically, he is European and is more closely related to current Europeans than any other people in the world. And that means that some of the earliest people in Europe were actually our forefathers,” Willerslev told the science website Videskab.dk. ”He is actually more closely related to Danes, Swedes, Finns and Russians than he is to the French, Spanish and Germans, so one could argue we are more originally European.”

I don’t know if the initial exchange was in English, or translated from Danish. And, journalists have been known to make “mistakes” in their quotations from scientists. But, taken at face value I’d have to say that this quote, and many of the inferences being made from this paper, strike me as “not even wrong.” Using the whole genome of this ancient man the authors generated fascinating results, but I am not quite so sure about the confidence presented in their interpretations. Some sentences jump out at me as anachronistic and incongruous. Consider:

Altogether, these results suggest that contemporary Siberian populations from the Yenisei basin derive part of their gene pool from a Eurasian HG population that shares ancestry with K14, but is more closely related to Scandinavian MHGs than to either MA1 or western European MHGs, indicating gene flow between their ancestors and Scandinavian Europe after K14 but prior to the Mesolithic.

It illustrates both the startling results which demand explanation , and the head-scratching assertions which are strewn about like ticking time bombs, due to the incongruity of their implications. Kostenki 14, K14, lived ~37,000 years ago. For most of the period between then and now Scandinavia, and much of Northern Europe was glaciated, and uninhabited. Much of the Yensei basin was also subject to glaciation. Therefore you can eliminate the possibility gene flow from the geographic region of Scandinavian Europe for much of this period because no humans lived in Scandinavian Europe, and likely in much of the Yensei basin as well. This is not a trivial point because the authors make assertions about the nature of migration, or lack thereof, in prehistory, so they need to be very clear and precise on these issues in regards to geographic provenance. The results and statistical genetic methods are complex enough as it is. Quotes like the one above make it very unclear whether the term Scandinavian is a semantic shorthand, likely, since glaciation is evident in a figure in their paper, or literal description, as the lay public and even non-close scientific readers are likely to infer. The major topline finding that is hard to dispute is that nearly 40,000 years ago on the plains of modern Ukraine an individual lived whose genetic makeup exhibited strong affinities to modern Europeans, in particular, Northern Europeans. This is not a trivial result because it adds more evidence to the model that West Eurasians and East Eurasians diverged before 40,000 years ago (earlier statistical genetic models utilizing computational techniques arrived at dates closer to ~20,000 years ago). Recently the genome of the man who lived about ~45,000 years further east in Siberia was analyzed, and found to exhibit genetic affinities with bothEast and West Eurasians. This implies that the differentiation of West and East Eurasians occurred in the interval between ~35 to 50 thousand years ago, aligning well with certain archaeological and paleontological findings. In addition, the tract length of Neandertal ancestry was longer in this individual than in moderns, just as it was in the Siberian genome, as one would expect. The admixture date was inferred to be on the order of ~50,000 years ago, again, in good alignment with expectations. The issues that I have rather are about the nature of the emergence of anatomically modern humans across Eurasia inferred from these results (and further). First, I can’t speak to the archaeology and ancient DNA analysis. I assume they had paleontologists look at the dating and what not, and it checked out. The dates and descriptions look plausible from what I know, but then I don’t know that much. Additionally, the ancient DNA looks good. Willerslev’s team is top notch, probably the only group within spitting distance of Svante Paabo’s in this area. With 2.4x coverage on the whole genome that’s good enough for reasonable genotype calling with ANGSD, and to compare with the HGDP data set and what not (~500,000 markers merged). This doesn’t mean that the archaeology and ancient DNA quality have no issues, but they aren’t obvious.

To the right you see an edited version of a figure from the paper. The barplot is something you’ll recognize as an admixture analysis. You can see that the European hunter-gatherer frequencies from 5,000 to 10,000 years before the present exhibit a very strong modal cluster affiliation, while the Neolithic farmers (to the right) are mixed. To the left you see the two ancient samples of K14 and MA1 (Mal’ta). They are hard to tease apart, though you see that K14 has a lot of the components altogether, like many modern Europeans. The map with the heated circles show genetic affinities from the f3 test, which basically takes a phylogenetic tree, with an outgroup, Mbuti pygmies, and the K14 individual, and another population, X. The outcome of the statistic can indicate the affinity and closeness between K14 and X (basically, the two populations posited to be a clade). The authors use several of these sorts of statistics, but the basic idea is the same, where allele frequencies across topologies should reflect shared (or lack thereof) drift history conditional on the topology being correct or not. In some cases the topology is not totally correct because of gene flow across the clades, so you infer admixture. It does seem rather evident that the K14 individual shares a lot of drift with Northern Europeans. Or more specifically Northern Europeans descend in large part from a population which also contributed to K14. The admixture plot confirms this.

All good so far. My main results qualm though can be found in the supplemental (which is free to anyone without access to the paper itself). In Science Willerslev tells Anne Gibbons that “What is surprising is this guy represents one of the earliest Europeans, but at the same time he basically contains all the genetic components that you find in contemporary Europeans—at 37,000 years ago.” The admixture analysis sort of confirms this, though admixture without a lot of scaffold in terms of what we know can be kind of confusing and like reading tea leaves. That’s why PCA is often useful since it summarizes the variation in a more straightforward manner, plotting out the largest independent components of variance within the data. Take a look at where K14 shakes out. I’ve placed a red pointer toward the K14 sample. In the first plot with all non-Africans K14 is smack the middle of the Central Asian cluster, clearly shifted toward East Asians. All the Europeans aside from Uralic and Turkic populations from Russia are a tight cluster, off to the right of the plot. In the second plot it is constrained more straightforwardly to a sample of Europeans and Middle Eastern populations. Previous PC1 had separated East Asians and Europeans, while PC2 had separeated Oceanieans and Amerindians. Now PC1 seems to separate ancient European hunter-gatherers from Middle Easterners and PC2 Early European Farmers (EFF) from Ma’lta and the Turkic groups with residual East Asian ancestral. Since K14 has the “Ancestral North Eurasian” affinity, it is shifted down toward Mal’ta, but since it is mixed it is not particularly close to the European populations. I point this out to suggest that summaries of the form that “someone just like modern Europeans existed 37,000 thousand years ago” are probably not helpful or illuminating, but that’s what we’re seeing in the press, and not just from the press itself. K14 was an ancient human being. Attempting to understand him as a combination of modern genetic variation is going to have shortcomings. This is obvious. Using “ancestral allele frequencies” derived from model-based admixture analysis to figure out his affinities is useful, but has limits, because those allele frequencies are informative of modern populations. Similarly, PCA is projecting him upon modern population genetic variation. Useful, but again, one must be careful. What’s the big takeway? Let me quote the last paragraph of the Science paper:

Our results further suggest that the early stages of the western Eurasian lineage were already complex (see alsoFig. 2). Besides its core affinities with subsequent European groups, K14 also shares alleles with European Neolithic farmers and contemporary people from the Middle East/Caucasus, which are not found in MA1 and western European MHGs, indicating genetic exchange between K14 and a Basal Eurasian Lineage (which eventually contributed to Neolithic groups) after the ancestors of MA1 and subsequent European MHGs had diverged. This implies that early AMH populations became structured early in their history, but already in the UP contained the major genetic components found in Europeans today. As such our findings show the existence of a meta-population structure in Europe from the Upper Paleolithic onwards, remnants of which are still found today, despite migrations to and from Europe since the UP. The early UP contribution is greater among northern than southern Europeans, in agreement with the southeast to west and north gene flow cline resulting from the expansion of Neolithic famers 9-6 ka cal BP (20, 45). However, descendants of the early UP population represented by K14 likely also contributed genes to western Siberian groups living around the mouth of the Yenisei River. Therefore, our findings support the view that these Uralic-speaking populations represent an ancient admixture between European and East Asian lineages. The recently proposed Holocene gene flow from East Asians into northern Europeans (21) can, in our view, be equally well explained by population structure of the hunter-gatherer meta-population within Europe. As such our results paint an increasingly complex picture of colonization history of Europe from the UP to today. Instead of inferring a few discrete migration events from Asia into Europe, we now see evidence that humans in Western Eurasia formed a large meta-population with gene flow in multiple directions occurring repeatedly and perhaps continuously.

The authors also present a modified schematic of Lazaridis et al. There are two aspects of the conclusion: 1) Many of the assertions are totally uncontroversial (e.g., “it’s complicated”). 2) Many of them seem to be challenging the model posited by publications coming out of David Reich’s lab, where they partner with Svante Paabo’s groups for the ancient DNA work. Let me quote Willerslev and Reich from the Gibbon’s piece in Science:

“There was a really large met-population that probably stretched all the way from the Middle East into Europe and into Eurasia,” Willerslev says. These people interbred at the edges of their separate populations, keeping the entire complex network interconnected—and so giving the ancient Kostenki man genes from three different groups. “In principle, you just have sex with your neighbor and they have it with their next neighbor—you don’t need to have these armies of people moving around to spread the genes.” [Willerslev] … Other researchers say that this new genome is important because “it is the first paper to document some degree of continuity among the first people to get to Europe and the people living there today,” says population geneticist David Reich of Harvard University, one of the authors on the triple migration model. It also is “a striking finding that the Kostenki 14 genome already has the three major European components present that we detect in modern Europeans,” says Johannes Krause of the University of Tübingen in Germany. But even if the man from Kostenki in Russia had all these elements 36,000 years ago, that doesn’t mean that other Europeans did, Reich says. His team’s DNA data and models suggest that Europeans in the west and north did not pick up DNA from the steppes until much later…. [Reich]

I’ve read the Seguin-Orlando et al. paper (and supplements) several times to try and be fair. What I don’t understand is why they can’t acknowledge the possibility that K14 did not leave modern descendants, and was part of an early population which did not end up flourishing. That is consistent with all their results after all, and, consistent with ancient DNA which seems to show a lot less admixture in Mesolithic groups than K14. The fact that Willerslev talks about meta-populations makes it even more confusing, since one of the aspects of meta-population dynamics is the likelihood of repeated population extinctions and re-colonizations. This seems entirely plausible across the European and Northern Eurasian plain during the last Ice Age, as humans retrenched and expanded multiple times. It’s been a while so I checked Wikipedia, and here’s a representative sentence reflecting what I recall learning: “Kritzer & Sale have argued against strict application of the metapopulation definitional criteria that extinction risks to local populations must be non-negligible.” So there’s an argument about whether extinctions are necessary or not. But it shows how critical they’ve been historically to model metapopulation (I think it makes the math easier). As for the idea that gene flows occurred through diffusion, obviously there’s a lot of that. But the punctuated turnover of mtDNA lineages in ancient DNA transects and the ability to infer admixture events from pulse fusion events seems to suggest a great deal of ancient demography could not be modeled in such a fashion. This paper focuses on Northern Eurasia, but in South Asia, Southeast Asia, and Africa, we see clear instances where genetically distinct populations fused rapidly due to demographic expansion enabled by cultural change. Perhaps Northern Eurasia is different, but cases in other parts of the world should scaffold our expectations. Overall I’m left somewhat more confused and interested. Addendum: One thing I want to emphasize. Willersleve seems to be implying that all the variation of West/North Eurasians in its basic algebraic constituents was present about ~10,000 years after the differentiation of non-Africans. Is it really plausible that the last 35,000 years, a time frame 3.5 times as long, is a coda to that? Perhaps. But color me a little skeptical. I suspect that we’ll get more clarity when we stop thinking of prehistoric populations simply as repositories of the history of extant populations. To see what I’m getting at, there are ~10,000 years separating K14 from East Asian populations alive at that time. There are ~35,000 years separating modern West/North Eurasians and East Asians from their putative ancestry populations. Even if you double the value for K14 vs. Paleolithic East Asians by two because there are two paths of drift, that’s still 20,000 years. The peculiarity of these ancient remains is always clear when you visualize them on TreeMix; they’re often very long branches awkwardly slotted into contemporary trees.

Slowly writing up reaction to Genomic structure in Europeans dating back at least 36,200 years which just came out in Science. It’s a rich & important paper, but I disagree with some of the stronger interpretations that Eske Willerslev has been putting out there in the media. More to come on that. Also, I’ve been thinking a lot about Toby Wilkinson’s The Rise and Fall of Ancient Egypt. It really made me a much stronger believer in the importance of institutional economics. I also got a copy of Frank McGlynn’s Marcus Aurelius: A Life. It’s got mixed reviews, but it seems strange that there are so few biographies of Aurelius’ life. It could simply be a function of the fact that Meditations serve as a window into his mind for moderns without comparison in relation to other Emperors of Rome. But it seems that it is important to understand the context of the world of the later Antonines, since arguably marks the end of the Classical Era and the first slouch toward Late Antiquity, like it or not.

Judith Rich Harris’ The Nurture Assumption is one of those books which I’ve been leaning on for over a decade, it’s so rich in novel and “counter-intuitive” facts which nevertheless just “make sense” in terms of how the world is as opposed to how we’re taught the world should be. The most important finding isn’t really about the importance of heritable variation in human behavior, though that’s not trivial, it’s that “shared [family] environment” matters so much less than you’d think. Quite a large fraction of the variation in outcomes is “non-shared environment,” which basically means we just don’t know, and so we can’t really control. In The Nurture Assumption it is posited that a large fraction of “non-shared environment” are peer group effects. One of the facts which the author uses to support this model is that the vast majority of people pick up their accents in their native language from their peers, not their parents. The telling is exception are children who are diagnosed as autistic. But I don’t know this literature in psychology well and so I’ve been repeating this fact for years without knowing the primary source. Now I think I’ve found it, Do children with autism acquire the phonology of their peers? An examination of group identification through the window of bilingualism:

Normal children whose parents have different native languages tend to develop an accent which is closer to their peers than to either parent. It was predicted that children with autism, because of their social deficits, might not acquire the accent of their peers, perhaps because of the lack of the normal drive to identify with peers. Bilingualism was used as a window into such social factors in language acquisition. Using audiotaped speech samples, the study found that in a sample of children with autism who were brought up in England and whose mothers were not English, 83.3% acquired their mother’s (non-English) accent. In contrast, among normally- developing siblings of children with autism who were brought up in England and whose mothers were not English, only 12.5% acquired their mother’s (non-English) accent. We suggest that such studies of unusual populations are of value in furthering our understanding of the larger population of children with autism, and the influences on normal social development.

The sample size was less than 100, and I’m very curious if this research has been followed up (using Google Scholar I didn’t stumble on anything very clear, but again, I’m not familiar with this discipline). My point in focusing on accent in the previous post is how we speak is often a social cue, rather than about language acquisition as such. Speaking of which, though it is common sense it is important to reiterate that children are basically savants when it comes to learning languages. Multi-lingualism is common in many parts of the developing world, and presumably it may have been in a more ethnically fragmented ancient world too. It’s a core human competency, not a signal of cognitive exceptionality.

When I arrived in the United States at the age of 4 I didn’t really speak English. I had learned a bit from my grandmother, who knew I was going to the United States at some point in the near future, but I was definitely not fluent when I entered kindergarten. I was given an IQ test on the first day of school and scored in the bottom 5 percent. I was given an IQ test on near the end of the school year, and scored in the top 5 percent. In first grade my teacher thought that I still exhibited some deficits in my English vocabulary (though not at all in my accent) so she sent home some books with my parents for me to read. Generally they were in the category of kitschy Americana, the city cousin going to visit her country cousin, and vice versa. By the time I had entered second grade any noticeable language deficits were gone.* I spent most of my youth being told how incredible it was that I didn’t have an accent from stupid baby boomers who seemed to think that people are born with their language and accent (kind of how multicultural theorists demand a “culturally appropriate” adoption).

This came to mind when reading Reihan Salam’s latest column in Slate, The Melting Pot Is Broken: How slowing down immigration could help us build a more cohesive and humane society. We are always told about Latino immigration, and how they are not fully assimilating. Living in California I have noticed that Mexican Americans (by which I mean those who I know to be born here) often speak with a mild accent. Basically a subcultural dialect. But more alarming to me are cases of children who arrived from Asia before puberty, but who still have an accent. These aren’t kids who grew up in the ghetto, but rather California college towns or Silicon Valley. Often the Balkanization of American society is attributed to socioeconomic gulfs, but this is not the case in the instances which shocked me.

The America I grew up in was clearly not the America after World War II, but its cultural template was still in the shadow of the baby boomers. That was an America where immigrants had to fit into a broader cultural framework as a matter of necessity and often preference. Yes, aspects of uniqueness were maintained, but encapsulation within one’s own community was the luxury for truly numerous subcultures, such as that of blacks or Mexicans Americans. Then multicultural theorists began to promulgate the idea of the “salad bowl” instead of the “melting pot” as a metaphor for American society. The optimistic take was that different threads would operate in harmony in the American mosaic. I’m moderately skeptical of that as a prediction for how the future will play out. Rather, I think the United States is on its way to becoming a much more humane version of Dubai. Economically productive in the aggregate, but dominated by a small coterie which disenfranchises the majority. That’s just a prediction. Since the Age of Jackson we’ve thought of ourselves a democracy more than a republic, and ancient Athens, with its core citizen class and ancillary metics, could be a plausible model for America in 2050.

* My wife still believes that I make a larger than expected number errors in assigning appropriate gender in pronouns when speaking because Bengali has no gender in pronouns.