On several occasions I’ve gotten into discussions with geneticists about the possibility of reconstructing someone’s facial structure by genes alone. Combined with advances in pigmentation prediction by genetics, this could put the sketch artist out of business! But all that begs the question: how heritable are facial features anyhow? Impressionistically we know that feature are broadly heritable. This isn’t a tenuous supposition, you see the resemblance over and over across families. All that being said, what are the specific quantitative heritability estimates? How do they relate to other traits we’re interested in? This review from the early 1990s seems to have what I’m looking for, The Role of Genetics in Craniofacial Morphology and Growth. Below is a table which shows averaged heritabilities for a range of facial quantitative traits from a large number of studies:

Read More

BusinessWeek‘s The Rise and Inglorious Fall of Myspace is a compelling read. But a huge piece of the puzzle which I thought was omitted was that Myspace was incubated in the short term bottom-feeder world to begin with, so the later fixation on revenue now rather than a long term vision may simply have been part of its original DNA. See this Planet Money podcast, MySpace Was Born Of Total Ignorance. Also Porn And Spyware, for what I’m talking about. As it is in the BusinessWeek piece Chris DeWolfe just tries to blame News Corp. Remember that DeWolfe and Tom Anderson sold out to Rupert Murdoch, while Mark Zuckerberg was uninterested in an immediate cash windfall. As far as the long term impact of Myspace I notice that the Urban Dictionary entry for ‘myspace angle’ is still more fleshed out than ‘facebook angle’, so the word “myspace” might still get preserved in this manner. In this way Myspace may resemble the audio cassette, which is still haunting our culture as the “mixtape”. Not surprisingly some young people are totally unaware that the tape portion actually refers to cassette tapes, since that technology was before their time.

In my long post below, Celts to Anglo-Saxons, in light of updated assumptions, I had a “cartoon” demographic model in mind which I attempted to sketch out in words. But sometimes prose isn’t the best in terms of precision, and almost always lacks in economy.

In particular I wanted to emphasize how genes and memes may transmit differently, and, the importance of the steps of going between A to Z in determining the shape of things in the end state. To illustrate more clearly what I have in mind I thought it might be useful to put up a post with my cartoon model in charts and figures.

First, you start out with a large “source” population and a smaller “target” population. Genetically only the migration from the source to the target really has an effect, because the source is so huge that migration from the target is irrelevant. So we’ll be focusing on the impact upon the target of migration both genetically and culturally.

To simplify the model we’ll imagine a character, whether genetic or memetic, where the source and target are absolutely different at t = 0, or generation 1. Also, these are discrete generations, and the population is fixed, so you can presume that it’s at carrying capacity. Migration of the outsiders into the target population from the source means less of the original native population in absolute terms (to be realistic this is bidirectional, so people are leaving the target too, but that’s not our concern here).

There are two time series which illustrate the divergent dynamics on both the genetic and memetic dimensions. In one series you see gradual and continuous migration from the source to the target population over 13 generations. In another there are two generations of massive migration, before and after which there is no migration. For the genetic character, imagine disjoint allele frequencies at generation 1. So at generation 1 the target population is at 100% for allele A, while the source is at 100% for allele B. Therefore migration of from the source to the target results in a decrease in the proportion of allele A, which is what is being measured on the y-axis. For the memetic character, imagine that it’s language. So at generation 1 100% in the target zone speak language A, while everyone in the source zone speak language B. Again, the frequency on the y-axis is of the proportion who speak language A in the target zone.

Read More

There have been some good posts at Gene Expression Classic you might want to check out. In particular:

Synaesthesia and savantism and Where do morals come from?. The second is a review of Braintrust: What Neuroscience Tells Us about Morality by Kevin Mitchell

Natural selection and the collapse of economic growth and Natural selection and economic growth by Jason Collins.

Earliest Art in the Americas: Ice Age Image of Mammoth or Mastodon Found in Florida. Claims that the a rendering of a elephant-like creature in Florida is at least ~13,000 years old because “this is the date for the last appearance of these animals in eastern North America.” If this is based on fossils probably you can fudge that a little lower, since first and last fossils tend to be a subset of the real interval of time.

Read More

1) Post from the past: The wisdom of Seinfeld. How far in the past? When I wrote this it was closer to the series finale of Seinfeld than to now!

Read More

Over the past week there have been three posts which I’ve put up which are related. Two of them have a straightforward relation, Britons, English, Germans, and collective action and Britons, English, and Dutch. But the third might not seem related to the other two, We stand on the shoulders of cultural giants, but it is. When we talk about things such as the spread of language through “elite emulation” or “population replacement” they’re rather vague catchall terms. We don’t decompose them mechanistically into their components to explore whether they can explain what they purport to explain. Rather, we take these phenomena for granted in a very simplistic black box fashion. We know what they’re describing on the face of it. “We” here means people without a background in sociolinguistics, obviously.

To give an example of the pitfall of this method, in much of Rodney Stark’s work on sociology of religion (the production before his recent quasi-apologetic material) his thinking was crisp and logical, but the psychological models were intuitive and naive and tended to get little input from the latest findings in cognitive science. In One True God he actually offers an explanation for why Christian Trinitarianism is psychologically more satisfying than the starker monotheism of the Jews and Muslims, or the more elaborated diffuse polytheism which predates monotheism.  All I will say is whether you are convinced or not, Stark’s argument has some logical coherency and a level of plausibility, until you explore the literature in cognitive science on conceptualization of supernatural agents. The psychological literature as outlined in Theological Incorrectness indicates quite clearly that no matter the explicit philosophical nature of God as outlined in a given religion, cognitively the human mind has strong constraints in terms of how it represents abstractions, so that the vast majority of believers conceptualize the godhead in an invariant manner. To be more clear about it, even though Jews and Muslims are strict monotheists and some Hindus conceive of themselves as polytheists,* their concrete mental image of the divine doesn’t vary much from person to person and religion to religion. As a practical matter Hindus who may accept the reality of a nearly infinite number of gods on paper still exhibit personal devotion to only a few. Jews and Muslims who are strict monotheists nevertheless may have cults of saints and lesser supernatural agents in their mental universe. There is a difference between saying you accept the reality of millions of gods, and actually being able to mentally focus on millions of gods. The latter is not possible, and that has real world consequences, in that the concrete difference between an avowed polytheistic and monotheist in terms of mental state is minimal at most. So the psychological contrasts which Stark assumes motivate higher order social differences turn out to be superficial word games in pure cognitive terms.**

Similarly, we know intuitively what “elite emulation” means. It’s self-evident in that the mass of the population emulates the elite in terms of their folkways. But how does this really play out? The description is just a description, it doesn’t elaborate on the process of how you get from A to Z. When I try and find references in the ethnographic literature, generally what I encounter is in as an aside. What has been gnawing at me are cases like the Bulgar assimilation into the Slavic substrate, and the Magyar assimilation of their own Slavic and Latinate substrate. What distinguishes these two cases? They’re two instances of mobile populations from the western margins of Inner Asia erupting into the eucumene. Even if they were not pure horse-nomads in the vein of the Huns, they were clearly amongst the last of these class of peoples to force themselves into the heart of Europe after the fall of Rome because of their obligate male militarization and mobility. In the case of the Bulgarians all that remains of their distinctive identity as a mobile Turkic population is their ethnonym.  In contrast in the case of the Magyars they imposed their Ugric language language upon the population which they dominated. Modern Hungarians don’t seem to be any genetically different from what you’d expect based on geography. This is in contrast with Anatolian Turks, who do seem to have a minority East Asian element. The emergence of a dominant Magyar ethnicity on the Hungarian plain in the early medieval period then is clearly an instance of elite emulation if there ever was one, in contrast to the absorption of the Bulgars into their substrate. But this is just a description, it doesn’t tell us why elite emulation worked in one zone, but not in another.

Read More

Changes in Diet and Lifestyle and Long-Term Weight Gain in Women and Men:

Within each 4-year period, participants gained an average of 3.35 lb (5th to 95th percentile, −4.1 to 12.4). On the basis of increased daily servings of individual dietary components, 4-year weight change was most strongly associated with the intake of potato chips (1.69 lb), potatoes (1.28 lb), sugar-sweetened beverages (1.00 lb), unprocessed red meats (0.95 lb), and processed meats (0.93 lb) and was inversely associated with the intake of vegetables (−0.22 lb), whole grains (−0.37 lb), fruits (−0.49 lb), nuts (−0.57 lb), and yogurt (−0.82 lb) (P≤0.005 for each comparison). Aggregate dietary changes were associated with substantial differences in weight change (3.93 lb across quintiles of dietary change). Other lifestyle factors were also independently associated with weight change (P<0.001), including physical activity (−1.76 lb across quintiles); alcohol use (0.41 lb per drink per day), smoking (new quitters, 5.17 lb; former smokers, 0.14 lb), sleep (more weight gain with <6 or >8 hours of sleep), and television watching (0.31 lb per hour per day).

I took the results when they controlled for other variables and filtered them all so that their p-values were 0.001 or less (in fact, of the ones below only “sweets and desserts” is p-value 0.001, all the others are below that). Nothing too surprising, but the magnitude of effect of french fries was pretty large:

Read More

“We only use 10% of our brain”. I don’t know where that idea originated but it certainly took off as a popular meme – taxi drivers seem particularly taken with it. It’s rubbish of course – you use more than that just to see. But it captures an idea that we humans have untapped intellectual potential – that in each of us individually, or at least in humans in general lies the potential for genius.

Part of what has fed into that idea is the existence of so-called “savants” – people who have some isolated area of special intellectual ability far beyond most other individuals. Common examples of savant abilities include prodigious mental calculations, calendar calculations and remarkable feats of memory. These can arise due to brain injuries, or be apparently congenital. In congenital cases, savant abilities are often encountered against a background of the general intellectual, social or communicative symptoms of autism. (The portrayal by Dustin Hoffman in Rain Man is a good example, based on the late, well known savant Kim Peek).

A new hypothesis proposes that savantism arises due to a combination of autism and another condition, synaesthesia. Synaesthesia is commonly thought of as a cross-sensory phenomenon, where, for example, different sounds will induce the experience of particular colours, or tastes will induce the tactile experience of a shape. But in most cases the stimuli that induce synaesthesia are not sensory, but conceptual categories of learned objects, such as letters, numbers, days of the week, months of the year. The most common types involve coloured letters or numbers and what are called mental “number forms”.

These go beyond the typical mental number line that most of us can visualise from early textbooks. They are detailed, stable and idiosyncratic forms in space around the person, where each number occupies a specific position. They may follow complicated trajectories through space, even wrapping around the individual’s body in some cases. These forms can be related to different reference points (body, head or gaze-oriented) and can sometimes be mentally manipulated by synaesthetes to examine them more closely at specific positions.

The suggestion in relation to savantism is that such forms enable arithmetical calculations to be carried out in some kind of spatial, intuitive way that is distinct from the normal operations of formal arithmetic – but only when the brain is wired in such a way to take advantage of these special reprepsentations of numbers, as apparently can arise due to autism.

It has been proposed that the intense and narrowly focused interests typical of autism can lead to prolonged practice of these skills, which thus emerge and improve over time. While certainly likely to be involved in the development of these skills, on its own this explanation seems insufficient. It seems more likely that these special abilities arise from more fundamental differences in the way the brains of autistic people process information, with a greater degree of processing of local detail, paralleled by greater local connectivity in neural circuits and reductions in long-range integration.

Local processing may normally be actively inhibited. This idea has been referred to as the tyranny of the frontal lobes (especially of the left hemisphere), which impart top-down expectations with such authority that they override lower areas, conscripting them into service for the greater good. The potential of the local elements to process detailed information is thus superseded in order to achieve optimal global performance. The idea that local processing is actively suppressed is supported by the fact that savant abilities can sometimes emerge after frontal lobe injuries or in cases of frontotemporal dementia. Increased skills in numerical estimation can also, apparently, be induced in healthy people by using transcranial magnetic stimulation to temporarily inactivate part of the left hemisphere.

This kind of focus on local details, combined with an exceptional memory, may explain many types of savant skills, including musical and artistic ones. As many as 10% of autistics show some savant ability. These “islands of genius” (including things like perfect pitch, for example) are typically remarkable only on the background of general impairment – they would be less remarkable in the general population. Really prodigious savants are much more rare – these are people who can do things outside the range of normal abilities, such as phenomenal mathematical calculations. In these cases, the increased local processing typical of autism may not be, by itself, sufficient to explain the supranormal ability.

The idea is that such prodigious calculations may also rely on the concrete visual representations of numbers found in some types of synaesthesia. This theory was originally proposed by Simon Baron-Cohen and colleagues and arose from case studies of individual savants, including Daniel Tammett, an extraordinary man who has both Asperger’s syndrome and synaesthesia.

I had the pleasure of speaking with Daniel recently about his particular talents on the FutureProof radio programme for Dublin’s Newstalk Radio. (The podcast, from Nov 27th, 2010, can be accessed, with some perseverance, here). Daniel is unique in many ways. He has the prodigious mental talents of many savants, for arithmetic calculations and memory, but also has the insight and communicative skills to describe what is going on in his head. It is these descriptions that have fueled the idea that the mental calculations he performs rely on his synaesthetic number forms.

Daniel experiences numbers very differently from most people. He sees numbers in his mind’s eye as occupying specific positions in space. They also have characteristic colours, textures, movement, sounds and, importantly, shapes. Sequences of numbers form “landscapes in his mind”. This is vividly portrayed in the excellent BBC documentary “The Boy With the Incredible Brain” and described by Daniel in his two books, “Born on a Blue Day” and “Embracing the Wide Sky”.

His synaesthetic experiences of numbers are an intrinsic part of his arithmetical abilities. (I say arithmetical, as opposed to mathematical, because his abilities seem to be limited to prodigious mental calculations, as opposed to a talent for advanced calculus or other areas of mathematics). Daniel describes doing these calculations by some kind of mental spatial manipulation of the shapes of numbers and their positions in space. When he is performing these calculations he often seems to be tracing shapes with his fingers. He is, however, hard pressed to define this process exactly – it seems more like his brain does the calculation and he reads off the answer, apparently deducing the value based at least partly on the shape of the resultant number.

Daniel is also the European record holder for rembering the digits of the number pi – to over 20,000 decimal places. This feat also takes advantage of the way that he visualises numbers – he describes moving along a landscape of the digits of pi, which he sees in his mind’s eye and which enables him to recall each digit in sequence. The possible generality of this single case study is bolstered by reports of other savants, who similarly utilise visuospatial forms in their calculations and who report that they simply “see” the correct answer (see review by Murray).

Additional evidence to support the idea comes from studies testing whether the concrete and multimodal representations of numbers or units of time are associated with enhanced cognitive abilities in synaesthetes who are not autistic. Several recent studies suggest this is indeed the case.

Many synaesthetes say that having particular colours or spatial positions for letters and numbers helps them remember names, phone numbers, dates, etc. Ward and colleagues have tested whether these anecdotal reports would translate into better performance on memory tasks and found that they do. Synaesthetes did show better than average memory, but importantly, only for those items which were part of their synaesthetic experience. Their general memory was no better than non-synaesthete controls. Similarly, Simner and colleagues have found that synaesthetes with spatial forms for time units perform better on visuospatial tasks such as mental rotation of 3D objects.

Synaesthesia and autism are believed to occur independently and, as each only occurs in a small percentage of people, the joint occurrence is very rare. Of course, it remains possible that, even though most people with synaesthesia do not have autism and vice versa, their co-occurrence in some cases may reflect a single cause. Further research will be required to determine definitively the possible relationship between these conditions. For now, the research described above, especially the first-person accounts of Daniel Tammett and others, gives a unique insight into the rich variety of human experience, including fundamental differences in perception and cognitive style.

Murray, A. (2010). Can the existence of highly accessible concrete representations explain savant skills? Some insights from synaesthesia Medical Hypotheses, 74 (6), 1006-1012 DOI: 10.1016/j.mehy.2010.01.014

Bor, D., Billington, J., & Baron-Cohen, S. (2008). Savant Memory for Digits in a Case of Synaesthesia and Asperger Syndrome is Related to Hyperactivity in the Lateral Prefrontal Cortex Neurocase, 13 (5), 311-319 DOI: 10.1080/13554790701844945

Simner, J., Mayo, N., & Spiller, M. (2009). A foundation for savantism? Visuo-spatial synaesthetes present with cognitive benefits Cortex, 45 (10), 1246-1260 DOI: 10.1016/j.cortex.2009.07.007

Yaro, C., & Ward, J. (2007). Searching for Shereshevskii: What is superior about the memory of synaesthetes? The Quarterly Journal of Experimental Psychology, 60 (5), 681-695 DOI: 10.1080/17470210600785208

In reading The cultural niche: Why social learning is essential for human adaptation in PNAS I couldn’t help but think back to a conversation I had with a few old friends in Evanston in 2003. They were graduate students in mathematics at Northwestern, and at one point one of them expressed some serious frustration at the fact that so many of the science and business students in his introductory calculus courses simply wanted to “learn” a disparate set of techniques, rather than understand calculus. The reality of course is that the vast majority of people who ever encounter calculus aim to learn it for reasons of utility, not so that they can grok the fundamental theorem of calculus. With the proliferation of tools such as Mathematica and powerful portable calculators fewer and fewer people are getting their hands dirty with calculus in an analytic sense, and more often see it as simply a “requirement” which they have to pass.

Calculus, and mathematics generally, is a clean and crisp human invention. In the late 17th century Isaac Newton and Gottfried Leibniz originated calculus as we understand it. Later thinkers extended their work. But for the vast majority of humans who have ever learned calculus it is simply a “black box” set of techniques which work rather magically. They did not contribute anything new to the body of knowledge which they drew upon. Mathematics is part of our cultural patrimony, we implicitly stand upon the shoulders of giants without apology. Such is to be human.

Read More

John Hawks points to a report in Science on some morsels of information about Ötzi-the-Iceman’s genetics, The Iceman’s Last Meal:

Also at the meeting, researchers led by geneticist Angela Graefen of the Institute for Mummies and the Iceman reported that they have succeeded in sequencing the Iceman’s whole genome, despite the highly fragmented nuclear DNA. The genome has already revealed some surprises. One preliminary finding shows that the Iceman probably had brown eyes rather than the blue eyes found in many facial reconstructions done by artists. Graefen and her colleagues are also examining the DNA to see if Ötzi possessed genetic predispositions to diseases such as arthritis, which other researchers have diagnosed based on radiological and other evidence.

I’m assuming we’ll know a whole lot more before the end of summer. So I’m going to go out on a limb and make a prediction based on what I suspect about the southern European genetic landscape ~5,000 years ago: Ötzi will be more like contemporary West Asian people, Georgians, Armenians, etc., than modern north Italians and south Germans are. Right or wrong, I hope the results will be interesting!