In 2002 I read The Blank Slate. With all due respect to Steven Pinker one of the most fascinating aspects of this book was actually a review of the work of another psychologist, Judith Richard Harris. Harris’ own views are explicated crisply in The Nurture Assumption. In it she reviews and expands on a major insight from behavior genetics: over the long term parental influence seems to be a relatively marginal predictor in terms of many behavioral traits. To be explicit, one can imagine a personality trait which varies in the population. The variation of genes may explain 40% of the variation of the trait. The variation in parental child-rearing techniques, “shared home environment,” may explain 10% of the variation of the trait. The remaining 50% of the variation may be “non-shared environment.” That basically means we don’t have a definitive explanation of what the 50% remainder is, though Harris posits that this consists to a great extent of peer groups.*

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Well, not really. But a new paper in PLOS GENETICS has a really weird speculation nested into the discussion of what seems a relatively banal paper on the phylogeography of South Americans. It’s a Y chromosomal survey of the populations of the New World, so it’s tracing the male lineage only. Because Amerindian populations likely went through at least one (more if you accept multiple migrations) bottleneck the variation on the Y chromosome is low. Ideally you’d be looking at tens of thousands of markers on the autosome, the non-sex inherited genome. But this group had a very good population coverage. Over 1,000 men from 50 tribal populations, with a focus on South America. Additionally, non-recombining markers are more manageable in terms of reconstructing demographic histories.

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A few days ago I came across this four year old article in The Wall Street Journal on the Naga Bhut Jolokia “ghost” pepper, which is reportedly hotter than Habanero. Since none of the local grocers carry the ghost pepper, I went online. I purchased some seeds. But I also ordered Dave’s Ghost Pepper Naga Jolokia Hot Sauce and Volcano Dust Bhut Jolokia Powder. The latter was spicy, but it actually wasn’t too potent. I’d expected a lot more. Think cayenne powder on steroids. On the other hand, the hot sauce was hot. And unlike Dave’s Insanity Sauce there were flavors besides the heat which one could discern. Unlike Dave’s Insanity the Dave’s Ghost Pepper doesn’t taste like it came out of a chemical plant. I heartily recommend it.

Update: First, people coming to this weblog for the first time should know that I moderate comments. So if you leave an obnoxious one it’s basically like an email to me (no one will see it). Second, the correlation between height and intelligence is not that high. This association is probably not going to be intuitively visible to anyone, but rather only shows up in large data sets. So please stop offering yourself as a counter-example of the trend (also, the key is to look within families, because the signal here is going to be swamped by other factors when you compare across populations). Third, a friend has sent me another paper which does confirm that even within sibling cohorts there does seem to be a correlation between height and I.Q. The problem is that it is a very small one, so you need large data sets with a lot of power to see it.

End Update

One moderately interesting social science finding is that there is a positive correlation between height and measured intelligence (e.g., on an I.Q. test). Setting aside the possibility that I.Q. tests designs are culturally biased against shorter people, one wonders why this is so. Height is a highly heritable trait where most of the variation within the population is due to variation as numerous genes. In other words, there isn’t a “tall” or “short” gene, but thousands and thousands of variants which shape the variation of the trait across the population. When I say it is highly heritable, I mean to imply that most of the variation in height in developed societies is due to genes (80-90%). As it happens intelligence is somewhat similar in its genetic architecture, heritable due to small effects across many genes. In general estimates for the heritability of intelligence tend to be somewhat lower, on the order of ~50% rather than 80-90%.

It is due to the highly polygenic nature that both of these traits have been posited as candidates for a “good genes” model of sexual selection. Presumably individuals with a higher mutational load will have lower intelligence and be shorter, all things equal, because these traits have extensive genome-wide coverage and are big targets. Geoffrey Miller’s The Mating Mind: How Sexual Choice Shaped the Evolution of Human Nature, was predicated on this logic. If the mutational load argument holds then the reduced I.Q. of shorter individuals may simply be due to the same cause: “bad genes.”

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Every few months someone asks me what I use to manage my papers. Stupidly, I don’t use anything. Or I haven’t. Over the past few weeks I’ve been playing around with PubChase and Mendeley. You probably know of the latter, and the fact that it’s been purchased Elsevier. Elsevier is what it is. Mendeley on the other hand is a firm that I have a positive view of, in part because of their culture of openness and support for the free flow of information, but also due to the fact that I’ve known their head of outreach for ten years. You trust people, not things. Mendeley‘s not a charity, and I don’t begrudge them their new resources now that they are under the corporate wing of Elsevier. Whether you’re pessimistic or optimistic about their future, I think caution is warranted.

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Remember that genetics (in the Mendelian sense) predates the understanding of what a genes was in a material sense (a segment of DNA) by 50 years.

Update: Feature was always there. Just hard to find.

23andMe did a site redesign. Most of it is user interface clean up, but there one particular cool function: if you have an individual’s pedigree up to grandparents you can see which allele they inherited. Just select “Family Traits” under “Family & Friends.”

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I remember the specific moment when I was 13 that I became aware of the 1950s hit “Why Do Fools Fall in Love” by Frankie Lymon & The Teenagers. I’m rather sure I heard it before, but it didn’t penetrate my consciousness. But as we all know puberty changes things, and the idea of love becomes more comprehensible. As I’ve grown older I’ve also started to ponder the lyrics a bit more. Not out of any sense of sensitivity toward music criticism, but because of the evolutionary implications. Here are some relevant sections:

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For whatever reason The New York Times has been putting out many articles on Myanmar recently. For example, Buddhist-Muslim Tensions Spread as 8 Detainees Die in Indonesia. Second, Ethnic Rifts Strain Myanmar as It Moves Toward Democracy. I’m a subscriber to The New York Times, so I think the paper of record is worthwhile. But quite often its international pieces lack historical and cultural context, and don’t impart the heart of the matter to readers. (see: The New York Times flubs basic facts about Islam) First, the simple part. The “religious conflict” in Myanmar is really just an ethnic-racial conflict. Demographic statistics from Myanmar are pretty woolly, so one can’t say anything with any great confidence, but it seems likely that the majority of Muslims in that nation are ethnic Rohingya. These Rohingya derive from agriculturalists who emigrated at some point in the last few centuries from eastern Bengal, and, that is the region which has always been predominantly Muslim. There are two giveaways as to their origin. First, their language (from Wikipedia):

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E. O. Wilson has a op-ed in WSJ which I find quite interesting, Great Scientist ≠ Good at Math:

For many young people who aspire to be scientists, the great bugbear is mathematics. Without advanced math, how can you do serious work in the sciences? Well, I have a professional secret to share: Many of the most successful scientists in the world today are mathematically no more than semiliterate.

…

This imbalance is especially the case in biology, where factors in a real-life phenomenon are often misunderstood or never noticed in the first place. The annals of theoretical biology are clogged with mathematical models that either can be safely ignored or, when tested, fail. Possibly no more than 10% have any lasting value. Only those linked solidly to knowledge of real living systems have much chance of being used.

Wilson has been on this for a bit now, to the bewilderment of some of the scientists I follow on Twitter (granted, the people I follow tend to be quantitative genomics types whose backgrounds may have been in math, physics, or statistics). Two immediate things come to mind reading this. First, a disproportionate number of the famous and successful scientists alive today are old, like E. O. Wilson. Just because you could get by with a certain level of mathematical fluency as an enfant terrible in the 1970s does not mean that that will cut it in the 2010s. Great scientists who are mathematically weak often have collaborators, post-docs, and graduate students, who do their bidding. It might be a different matter if you aren’t one of the Great Ones of the earth. From what I can tell scientists who are doing the hiring who don’t have mathematical skills prefer candidates who do have mathematical skills.

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