One of the major shifts in thinking about language came in 1990, when Steven Pinker and Paul Bloom published their groundbreaking paper: Natural language and natural selection. In it, they argue natural selection was the central process in shaping the biological structures underpinning language. Since then, the field of language evolution has blossomed into a truly multidisciplinary subject. Yet now, I believe we are in the process of undergoing another paradigm shift: incorporating cultural evolution.

For some features, particularly the physical capacity to produce and receive multiple vocalizations, there is ample evidence for specialisation: a descended larynx, thoracic breathing, and several distinct hearing organs. Given that these features are firmly in the domain of biology, it makes intuitive sense to apply the theory of natural selection to solve the problem: humans are specially adapted to the production and reception of multiple vocalizations. Yet Pinker and Bloom’s argument is found somewhat wanting when extended to incorporate the notion that natural selection shaped specialised mental organs, or modules, for acquiring language. First and foremost, the notion of a putative language acquisition device (commonly referred to as LAD) is not an established fact: rather, it’s derived from Noam Chomsky’s arguments from the poverty of the stimulus (POTS) and assumptions that all languages are essentially the same in structure, but differ in their sound systems and vocabularies.

As such, under the stewardship of Pinker, Chomsky and others, the origin, evolution and acquisition of language is primarily seen as a biological question to be answered. Whilst it is certain that biology plays a role in the evolution of language, its exact purpose is still contentious in light of new research emerging from theories into cultural evolution. A notable instance came at the 2009 CogSci conference, where some of the leading researchers into the cultural evolution of language met up at a symposium, namely: Nick Chater (philosophy), Thomas L. Griffiths (Bayesian analyses), Simon Kirby (evolutionary psycholinguistics) and Morten H. Christiansen (molecular genetics). Each of these individuals are key influences on my own thinking in regards to language evolution (Simon Kirby was formerly my course supervisor at Edinburgh), and I think it is worthwhile to dedicate a few paragraphs discussing their ideas.

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Given this is my first post on GNXP I guess the first place to start is with a brief background: my main areas of study are focused on language, evolution and anything else unfortunate enough to find itself in between. Over the last year much of my time was spent at Edinburgh University, where I graduated with an MSc in the Evolution of Language and Cognition. More recently, however, I’ve found myself focusing on gene-culture co-evolution, cumulative culture and demography. So I suppose my role at GNXP will largely involve me expounding upon all these areas of research – something I’ll begin fairly soon. Until then, here’s an abstract of a very interesting paper I read this morning on nonhuman vocal learning in Bengalese Finch:

Humans learn to speak by a process of vocal imitation that requires the availability of auditory feedback. Similarly, young birds rely on auditory feedback when learning to imitate the songs of adult birds, providing one of the few examples of nonhuman vocal learning. However, although humans continue to use auditory feedback to correct vocal errors in adulthood, the mechanisms underlying the stability of adult birdsong are unknown. We found that, similar to human speech, adult birdsong is maintained by error correction. We perturbed the pitch (fundamental frequency) of auditory feedback in adult Bengalese finches using custom-designed headphones. Birds compensated for the imposed auditory error by adjusting the pitch of song. When the perturbation was removed, pitch returned to baseline. Our results indicate that adult birds correct vocal errors by comparing auditory feedback to a sensory target and suggest that lifelong error correction is a general principle of learned vocal behavior.

If you noticed my highlighted section then, yes, I do have a picture of said headphones, stylishly modelled by Ben Finch:

Besides the picture, the paper’s well worth reading for those of you interested in language-learning and its relationship to song-learning in Finches.

Citation: Sober & Brainard. Adult birdsong is actively maintained by error connection. Nature Neuroscience, 2009; 12 (7): 927-932 DOI: 10.1038/nn.2336.

According to this survey done by Zogby International. The numbers:

42% Muslim
9% Christian
6% Jews
5% Zoroastrian
7% Bahai
31% “Other” (the pollsters presume this is mostly those with “No religion”)

The sample size was small, only around 400. And it seems really strange that there was a religious option for “Other” but not “No Religion,” but perhaps the pollsters simply weren’t expecting that so many people wouldn’t select the religion of their cultural tradition. I was surprised by the low proportion of Jews (several Persian American actors are Jewish), and high proportion of Zoroastrians. Of course Zoroastrians emigrated in large numbers, but their population base in Iran itself wasn’t that huge to begin with, European ethnographers were shocked to “discover” that they were still a living community in the 19th century (part of this was that they isolated themselves in remote areas to escape Muslim persecution). One hypothesis: some Iranian Americans identify as Zoroastrian to reassert their Persian cultural heritage even if they are from traditionally Muslim families (this has happened in Tajikistan somewhat, though only among intellectuals, as secularization during the Soviet period made it psychologically feasible for some to simply “leap-frog” the Muslim period back to their presumed primal identities).

Obviously Iranian Americans are very different from people in Iran. Americans sometimes assume that the anti-clerical attitude of many Iranians indicates a general anti-religious stance, but this is not evident in The World Values Survey. 16% of Iranians consider themselves “not religious” while 84% consider themselves “religious.” 0.1% were convinced atheists, out of a sample size of ~2500 (survey taken in 2005). As a comparison in Turkey 16.9% are “not religious” while in Egypt it is 7.5%. For a Middle Eastern country Iran is actually relatively on the secular side, but only for a Middle Eastern country.

Of course there is no reason that the demographics of an immigrant community would represent well that of the source region. An enormous proportion of people whose ancestors came from the Russian Empire were Jews. Arab Americans in the United States are much more likely to be Christian or other religious minorities (Casey Kasem is Druze). Until recently the rule-of-thumb has been that a majority of Arabs in the United States are Christian, not Muslim, but I suspect that is no longer true. Many people of part Arab heritage (e.g., the 1980s pop singer Tiffany) may no longer identify as Arab (and Christian Arabs seem to have had high outmarriage rates), and the recent immigrant waves have been much more Muslim in composition (this makes some sense since there simply aren’t that many Arab Christians left in the Middle East, though numerically the Copts are still substantial because of Egypt’s large base population).

A final note on Iranian Americans: did the high frequency of those with no religious affiliations emerge in the United States, or was that due to the selection biasing of the Iranian migrants? One can imagine that Iranian Communist intellectual contingent may have been irreligious, but I would assume that educated Iranians would generally have had a nominal religious affiliation to begin with. But with the option to defect in the United States, combined with a secular reaction to make themselves distinctive from the Iranian theocracy, I suspect that the generation born or raised in the United States had less use for adherence to a cultural Islam. In other words, the extent of Iranian American secularity may be as contingent as the prevalence of Latoya face & small-dog ownership among female Tehrangelinos.

(other interesting, if unsurprising, data at thePDF)

Interesting post, Culture and the human genome: a synthesis of genetics and the human sciences, at Replicated Typo. Looks like an interesting blog, not updated that often, but the posts have value-add. Definitely adding to my RSS reader. My main complaint about the weblog are the annoying little Snap div pops. Is there anyone out there who thinks those things are awesome?

The lta4h Locus Modulates Susceptibility to Mycobacterial Infection in Zebrafish and Humans:

Exposure to Mycobacterium tuberculosis produces varied early outcomes, ranging from resistance to infection to progressive disease. Here we report results from a forward genetic screen in zebrafish larvae that identify multiple mutant classes with distinct patterns of innate susceptibility to Mycobacterium marinum. A hypersusceptible mutant maps to the lta4h locus encoding leukotriene A4 hydrolase, which catalyzes the final step in the synthesis of leukotriene B4 (LTB4), a potent chemoattractant and proinflammatory eicosanoid. lta4h mutations confer hypersusceptibility independent of LTB4 reduction, by redirecting eicosanoid substrates to anti-inflammatory lipoxins. The resultant anti-inflammatory state permits increased mycobacterial proliferation by limiting production of tumor necrosis factor. In humans, we find that protection from both tuberculosis and multibacillary leprosy is associated with heterozygosity for LTA4H polymorphisms that have previously been correlated with differential LTB4 production. Our results suggest conserved roles for balanced eicosanoid production in vertebrate resistance to mycobacterial infection.

Figure 6C has a mortality curves for patiens from meningeal TB:

Interestingly, heterozygote advantage against tuberculosis has been offered as the reason for the high frequency of the cystic fibrosis allele in Europeans. TB has been around for at least 10,000 years.

ScienceDaily covers this paper, and a few other TB related ones, in the most recent issue of Cell.

Citation: Tobin et al. The lta4h Locus Modulates Susceptibility to Mycobacterial Infection in Zebrafish and Humans. Cell, 2010; 140 (5): 717-730 DOI: 10.1016/j.cell.2010.02.013

I’m hearing about rumblings at 23andMe, and not in a good way. The company made a big splash a few years ago, and came highly recommended by friends (e.g., “They know their science, and have a bottomless pool of money”). This story at BNET got my attention though, and confirmed what many have been hinting at, or just telling me straight-up. Let’s start the from the beginning. Back in late 2008 23andMe seemed absolutely untouchable. Here’s Andrew Yates of Think Gene from then:

People, 23andMe isn’t going anywhere. They are the Bill & Melinda Gates Sergey & Anne Brin Foundation, Silicon Valley style. Anne Wojcicki is married to Sergey Brin, so 23andMe has access to all the talent, connections, and capital 23andMe would ever need to make 23andMe work. Thus, assuming 23andMe doesn’t do anything egregious, they will exist for as long as Mrs. Anne Wojcicki Brin pleases it to be so. If 23andMe shuts down, it won’t be for some mundane reason like the bills weren’t paid, it will be because Anne felt like it.…What, does that offend your meritocratic, democratic, American dream sensibilities? Too bad. Go get an Ivy+ degree and marry your own richest man in the world.

This seemed to be a reasonable assessment, and I know I shared it. Case closed.

And the momentum kept going for a while. But since then something seems to have gone wrong in the narrative. Check out this this comment thread at Dr. Daniel MacArthur’s. There’s apparently some lack of clarity about why Linda Avery, the co-founder, left. Who would want to leave a company which had access to Sergey Brin’s pocketbook?

As a friend put it to me, what kind of co-founder leaves a successful startup mid-stream voluntarily? (excepting Jawed Karim) You can get some ideas why from the Glassdoor reviews:
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Aziz points me to a Newsweek article, History in the Remaking, on the Göbekli Tepe temple complex. The piece is a bit breathless:

Standing on the hill at dawn, overseeing a team of 40 Kurdish diggers, the German-born archeologist waves a hand over his discovery here, a revolution in the story of human origins. Schmidt has uncovered a vast and beautiful temple complex, a structure so ancient that it may be the very first thing human beings ever built. The site isn’t just old, it redefines old: the temple was built 11,500 years ago—a staggering 7,000 years before the Great Pyramid, and more than 6,000 years before Stonehenge first took shape. The ruins are so early that they predate villages, pottery, domesticated animals, and even agriculture—the first embers of civilization. In fact, Schmidt thinks the temple itself, built after the end of the last Ice Age by hunter-gatherers, became that ember—the spark that launched mankind toward farming, urban life, and all that followed.

A trivial point is that it was a spark at most, not the spark, as there are at least two independent sequences of the origination of agriculture leading to cities and the complex of cultural traits which we label “civilization.” A larger point is that I suspect it is incredible to us that hunter-gatherers could engage in such coordination because our model of what hunter-gatherers are capable of is constrained to Arctic peoples, the Bushmen and the Pygmies, and these populations are selection biased toward marginal lands which agriculturists were unable to exploit. In contrast, hunter-gatherers before agriculture were resident in much richer territory, and probably had more complex societies than we’re used to imagining. Probably something closer to the native populations of the North American Pacific Northwest.
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The ideas of gene-culture coevolution have percolated all the way to the foodie-sphere, over at Epi-Log at Epicurious, The Health Trend of the Future: The Ethnic-Group Diet?:

So, maybe at some point in the future, a visit to the doctor will involve a full genetic workup followed by a prescribed diet tailored to our individual makeup. I might be advised to eat lots of whole grains and dairy products, while someone else might do better on mostly meat and vegetables. This is probably a long way off though—there’s still a lot of science to be filled in.

The “low hanging fruit” like lactose tolerance has been around a long time. Gary Nabhan wrote Why Some Like It Hot: Food, Genes, and Cultural Diversity in 2004. In any case, family background is obviously going to be important, but information from your ethnic background is also probably useful, especially if you have a small family. Ultimately nutrigenomics might advance far enough that we can get personalized recommendations, but if much of the genetic variation is part of the missing heritability than population-level information might be critical for a long time to come. Additionally, population-level information might be relevant as genetic variations which we know about may expression differently conditional on genetic background.

But a consideration that’s not totally trivial is that diets can change very fast. The Columbian Exchange resulted in the introduction of chili peppers to much of Asia, to the point where the extent of their usage in the local cuisine can be diagnostic as to regional origin. And of course potatoes are a relatively new staple in much of Europe. Though in both of these cases the basic nutritional value or culinary role simply substitutes for what was already on hand, starch in the case of the potato and spice in the case of chili pepper.

PNAS has a new study out on the “modest” association between GABRA2 and “alcohol dependence.” The odds ratios pretty weak. But what struck me is that the populations they looked at was mostly European and African American. I wonder why these research programs just don’t focus on Native Ameicans; who are operationally an admixed population (European + Native American) and manifest a lot of alcohol dependence.

Citation: Laura J. Bierut, Arpana Agrawal, Kathleen K. Bucholz, Kimberly F. Doheny, Cathy Laurie, Elizabeth Pugh, Sherri Fisher, Louis Fox, William Howells, Sarah Bertelsen, Anthony L. Hinrichs, Laura Almasy, Naomi Breslau, Robert C. Culverhouse, Danielle M. Dick, Howard J. Edenberg, Tatiana Foroud, Richard A. Grucza, Dorothy Hatsukami, Victor Hesselbrock, Eric O. Johnson, John Kramer, Robert F. Krueger, Samuel Kuperman, Michael Lynskey, Karl Mann, Rosalind J. Neuman, Markus M. Nöthen, John I. Nurnberger, Jr., Bernice Porjesz, Monika Ridinger, Nancy L. Saccone, Scott F. Saccone, Marc A. Schuckit, Jay A. Tischfield, Jen C. Wang, Marcella Rietschel, Alison M. Goate, John P. Rice, and as part of the Gene, Environment Association Studies (GENEVA) Consortium, A genome-wide association study of alcohol dependence , doi:10.1073/pnas.0911109107

Nicholas Wade has an article in The New York Times, Human Culture, an Evolutionary Force. One point to highlight:

By this criterion, many of the genes under selection seem to be responding to conventional pressures. Some are involved in the immune system, and presumably became more common because of the protection they provided against disease. Genes that cause paler skin in Europeans or Asians are probably a response to geography and climate.

But even in this case these non-cultural targets of selection have an ultimate cultural cause. The Eurasian pathogen environment is strongly shaped by the fact that humans have lived at high densities under nutritional stress for thousands of years. The uniqueness of the Eurasian adaptations are evident whenever these populations encounter hunter-gatherers. Adaptation to malaria is something which most biologists accept as a clear case of natural selection, but malaria has become ubiquitous only within the past 5-10,000 years in many regions because of ecological changes wrought by humans as they shifted their culture (clearing land for agriculture).

More distantly, even if you assume that light skin evolved due to the need to synthesize endogenous vitamin D at high latitudes, what were H. sapiens doing at very high latitudes anyhow? The push into Siberia within the past 30,000 years seems to have been a function of behavioral modernity, contingent upon cultural changes, which themselves may have been contingent upon biological endowments.

It’s a pretty tangled ball. But as a genuine takeaway I have begun to wonder whether the protean nature of human culture, and its relevance for changes in gene frequency, imply that models which posit adaptation driving genetic architectures toward equilibria may not be particularly helpful. In other words, the adaptive landscape may be too volatile for gene frequencies to ever attain a stable fitness peak.