Phoneme Inventory Size and Demography
Mirrored from A Replicated Typo
It’s long since been established that demography drives evolutionary processes (see Hawks, 2008 for a good overview). Similar attempts are also being made to describe cultural (Shennan, 2000; Henrich, 2004; Richerson & Boyd, 2009) and linguistic (Nettle, 1999a; Wichmann & Homan, 2009; Vogt, 2009) processes by considering the effects of population size and other demographic variables. Even though these ideas are hardly new, until recently, there was a ceiling as to the amount of resources one person could draw upon. In linguistics, this paucity of data is being remedied through the implementation of large-scale projects, such as WALS, Ethnologue and UPSID, that bring together a vast body of linguistic fieldwork from around the world. Providing a solid direction for how this might be utilised is a recent study by Lupyan & Dale (2010). Here, the authors compare the structural properties of more than 2000 languages with three demographic variables: a language’s speaker population, its geographic spread and the number of linguistic neighbours. The salient point being that certain differences in structural features correspond to the underlying demographic conditions.
With that said, a few months ago I found myself wondering about a particular feature, the phoneme inventory size, and its potential relationship to underlying demographic conditions of a speech community. What piqued my interest was that two languages I retain a passing interest in, Kayardild and Pirahã, both contain small phonological inventories and have small speaker communities. The question being: is their a correlation between the population size of a language and its number of phonemes? Despite work suggesting at such a relationship (e.g. Trudgill, 2004), there is little in the way of empirical evidence to support such claims. Hay & Bauer (2007) perhaps represent the most comprehensive attempt at an investigation: reporting a statistical correlation between the number of speakers of a language and its phoneme inventory size.
In it, the authors provide some evidence for the claim that the more speakers a language has, the larger its phoneme inventory. Without going into the sub-divisions of vowels (e.g. separating monophthongs, extra monophtongs and diphthongs) and consonants (e.g. obstruents), as it would extend the post by about 1000 words, the vowel inventory and consonant inventory are both correlated with population size (also ruling out that language families are driving the results). As they note:
That vowel inventory and consonant inventory are both correlated with population size is quite remarkable. This is especially so because consonant inventory and vowel inventory do not correlate with one another at all in this data-set (rho=.01, p=.86). Maddieson (2005) also reports that there is no correlation between vowel and consonant inventory size in his sample of 559 languages. Despite the fact that there is no link between vowel inventory and consonant inventory size, both are significantly correlated with the size of the population of speakers.
Using their paper as a springboard, I decided to look at how other demographic factors might influence the size of the phoneme inventory, namely: population density and the degree of social interconnectedness.
10 Questions for Hugh Pope
I have posted a Q & A with author Hugh Pope over at Discover. Other 10 Questions can be found here.
Looking at India’s “Deep North” – Part I
Razib has an excellent post with information familiar to India-watchers: India is very diverse. In particular, it has a South which does well on levels of human development (and increasingly income as well); while the states in the “BIMARU” North perform abysmally on both economic and human development indicators. These kinds of disparities are frequently overlooked by commentators — both in India and elsewhere — who have as their primary analytical unit the nation-state.
Will Wilkinson has dubbed a related phenomenon the “UN Fallacy” — the error of assuming that two areas can be usefully compared simply because they are nation-states. So, for instance, you hear nonsense related to how “China has overtaken Japan.” Of course, on a per capita basis China remains poorer than El Salvador. Yet because the Chinese have aggregated themselves into a relatively large political unit, we think of the Chinese as “getting rich” and the Salvadorians as “poor.” We think of India as surging ahead, though it has more poor people than Africa.
Coloured hearing in Williams syndrome
The idea that our genes can affect many of the traits that define us as individuals, including our personality, intelligence, talents and interests is one that some people find hard to accept. That this is the case is very clearly and dramatically demonstrated, however, by a number of genetic conditions, which have characteristic profiles of psychological traits. Genetic effects include influences on perception, sometimes quite profound, and other times remarkably selective. A recent study suggests that differences in perception in two conditions, synaesthesia and Williams syndrome, may share some unexpected similarities.
Williams syndrome is a genomic disorder caused by deletion of a specific segment of chromosome 7. Due to the presence of a number of repeated sequences, this region is prone to errors during replication that can result in deletion of the intervening stretch of the chromosome, which contains approximately 28 genes. The disorder is characterised by typical facial morphology, heart defects and a remarkably consistent profile of cognitive and personality traits. These include mild intellectual disability, with relative strength in language and extreme deficits in visuospatial abilities (including being able to perceive the relationships of objects in 3D space and to construct and mentally manipulate 3D representations). Williams patients are also highly social – often to the point of being over-friendly – empathetic and very talkative. This behaviour may belie a high level of anxiety, however.
One of the most remarkable features of Williams syndrome is the strong attraction of patients for music. Many show a strong interest in music from an early age and greater emotional responses to music. They are also more likely to play a musical instrument, some using music to reduce anxiety. A recent study from Elisabeth Dykens and colleagues adds a new twist to this story. They found in a neuroimaging experiment that in addition to activating the auditory cortex, music also stimulates visual activity and perceptions in Williams patients. In fact, this is not specific to music – non-musical sounds had the same or even stronger effects.
Y Chromosome IV: Recombination Suppression
Last time we discussed the discovery of “evolutionary strata” on the human X chromosome – there are distinct blocks on the X that stopped recombining with their Y-homologs at different times causing the Y chromosome’s genes to appear scrambled in order. How can this happen?
Submitting your own links to GNXP
I’ve decided to add a “user generated content” component to this weblog. The links submitted by users will now be at the top left. If you read this weblog, you know the stuff that readers (you) might find of interest. The main issue is getting to where you can submit the links. First, initially I’ve limited the submission ability to those who have registered an account (that’s ~90 people right now). Because of the way the cookies work in WordPress you can see the user submit option only if you’re in the /wp directory, so http://www.gnxp.com/wp/. I’ve changed the link on the header so that it sends you to this directory. You’re also in the directory when viewing an individual post (I know that I can fix this by changing default WordPress settings, but it seems to break the permlinks to individual entries). I’m especially interested in papers, data sources, etc. I will be deleting crap or inappropriate content as well. The image to the right shows where the user submit form will be, underneath the authors list. But remember you’ll only see it if 1) you’re logged in, 2) you’re in /wp/.
Also, I’ve created a twitter account just for this weblog. My personal twitter account has only my content, but this new one will have content from everyone who posts on this weblog (nothing there currently since I set it up after the last post). Finally, I added a retweet widget. You can retweet with the current sharing widget at the bottom of posts, but I figure this is more convenient and obvious for most people.
Note: Links are not going to be associated with a user, so they’re anonymous submissions. If particular users are purposely submitted crap I may have to revise that policy!
Addendum: I get a fair number of emails with links. I don’t have the time to respond to all the submissions, or even blog about them, so I figured this would be a useful outlet.
Why is Israel So Poor?
File this one under the list of “infrequently-asked questions.” This is an issue I’ve discussed extensively over at TGGP’s blog. Basically, here is the puzzle: Jews are among the most wealthy groups in America, with a median income close to $100,000 a year.
Naively, you might expect Israel to be about as wealthy. Isreal is, after all, a country filled with Jews. Yet Israel is far poorer than a hypothetical “Jewish-America,” and is also poorer than America in general. Israel’s wealth is a little difficult to parcel out due to the presence of a large Arab minority. Yet even if you assign an income of non-Jews of 0, you arrive at an Israeli per capita GDP of $36,000. By comparison, both Ireland and America are in excess of $45,000 per capita. Corrections for Purchase Price Parity correct for some, but not all, of this difference.
This is part of a general phenomenon. As Tino has calculated, virtually all hyphenated-Americans do better in America than their home country.
With respect to European countries, this makes sense. As has been argued elsewhere, America/Europe income differences are due in no small part to different taxation policies. Lower marginal tax rates do have long-term effects on standards of living, even if they don’t “pay for themselves.”
Figuring out what’s going on in Israel is a bit trickier. This country looks more free-market than European standards. There are two crucial issues here:
The Fame of Price
I haven’t posted here for some time, but Razib’s recent review of a book by Oren Harman about George Price prompted me to read the book, and I think I will have a few things worth saying about Price. Harman’s book itself is a good biography, but is sketchy on the mathematical details of Price’s work (as one would expect in a book aimed at a general audience), so it encouraged me to look closely at Price’s original papers for the first time. A few years ago I wrote a commentary on ‘Price’s Equation’, but I based my discussion largely on a treatment by W. D. Hamilton, which I now find is not quite the same as Price’s own approach. I have not seen any close analysis of Price’s own key papers. (The descriptions in Harman’s book are taken almost verbatim from a treatment by Steven A. Frank which itself is very brief and a long way from Price’s original.) My main purpose will therefore be to give a commentary and (I hope) elucidation of Price’s own derivations.
All this will take me a week or two to prepare. Meanwhile, I have been reflecting on the recent upsurge of interest in Price. Not many scientists attract the attention of biographers, unless they are in the class of Galileo, Darwin, Newton, or Einstein, so what is special about Price? More generally, what makes some scientists and areas of science attractive to popular historians and biographers, while others are not?
These thoughts were prompted partly by the references in Harman’s book to Cedric (C. A. B.) Smith. Smith was extremely important in Price’s career, being among the first to take an interest in his biological work and providing him with the facilities to continue it. He continued to support Price in various ways, despite Price’s eccentricities, and he must have been a kind and tolerant man (it is no surprise to find that he was a Quaker). But the point I want to make is that Smith was an important scientist in his own right. He made notable contributions to both genetics and pure mathematics. In purely academic terms he was far more successful than Price, holding J. B. S. Haldane’s former chair in genetics at the University of London, and obtaining various awards and distinctions. Yet nobody is likely to write a popular biography of C. A. B. Smith. So what is the difference between Smith and Price?
A first obvious possibility is that Price’s work, though sparse in quantity, was in fact more fundamental and influential than Smith’s. I think this is probably true, but it can hardly be the whole explanation. Fundamental work (like the Lotka-Volterra equations in ecology) does not necessarily make the stuff of popular biography.
When to blame your parents, and for what
Studies linking some aspect of parental behaviour with some trait in their offspring are depressingly common in the sociological literature. Though these studies typically only report a correlation between parental behaviour and whatever the trait is in the offspring, the implication, and often the explicit conclusion, is that one causes the other. These kinds of stories get huge play in the popular press (and in the blogosphere), where the conclusion of a causative relationship is rarely challenged. For example, the finding that children who grow up with more books in the house are more successful academically is taken as evidence that simply having books around makes kids smarter.
How much of the genome is transcribed? Or, the utility of a good genome browser
Recent genome-wide association studies have identified a large number of non-genic regions associated with disease risk; the standard interpretation of this observation is that these are regions involved in gene regulation. A few years back, though, another possibility was raised: what if there are simply a large number of genes in the human genome that we don’t know about yet? This hypothesis came from the observation, using gene expression microarrays, that there appeared to be much more transcription in the human genome than currently annotated (for example, [1]).
A new study, however, throws a bit of cold water on this possibility [2]. Using RNA sequencing, the authors show that 1) there doesn’t appear to be that much unannotated transcription, and 2) most of the unannotated transcription that does exist is connected in some way to previously known genes. I don’t want to focus too much on these observations; however, I do want to spend a bit of time on the new transcription that they do find. In particular, they identify ~8,000 novel, short, unspliced transcripts, some of which show evidence of evolutionary conservation. This seems like quite a few! However, my feeling is that many of these are not true transcripts, but rather experimental artifacts. Let me explain why.
Read the rest of this entry »
Gene-culture interaction in Koreans and Americans
Genes and culture: OXTR gene influences social behaviour differently in Americans and Koreans. Korean Americans are more like white Americans than Koreans in the pattern of the effect of the allele on behavior.
Google Public Data Explorer
One of the main issues that we as human beings have is that we don’t have a gestalt understanding of social data, and its change over time. Among biologists one of the major recurring problems is the gloominess which is a consequence of the Malthusian mindset (which is understandable because of their professional bias) which has a hard time understanding that the human species is far healthier and wealthier today than it was in 1960. Below the fold is something I cobbled together in 30 seconds with Google’s public data explorer. On the y-axis is the log-transformed total fertility rate, and the x-axis the life expectancy. I’ve highlighted a few polities to show different trajectories since 1960.
Defining developmental disorders through genetics
To many people, the term “autism” suggests a specific disorder – one with characteristic and recognizable symptoms, presumably reflecting the same underlying cause. In fact, no such disorder exists. Autism refers to a variable spectrum of symptoms – including deficits in social interaction, impaired communication (especially a delay in developing language), narrow, restricted interests and stereotyped behaviours. Any one child who is diagnosed with autism may show only some of these symptoms. There is a wide range of IQ in autism, including very high levels seen in what has been known as Asperger’s syndrome, but the average is about 70. There is also a high incidence of epilepsy (around 10%).
Y Chromosome III: Evolutionary Strata!
Last time we discussed the composition of the human Y chromosome. Today we will examine one of the classes described by Skaletsky et al. (2003), the X-degenerate class, in more detail.
The primary model for Y-chromosome degeneration is a decrease in X-Y recombination. Because and X and Y chromosomes are not kept the same by swapping DNA segments with each other, but the X can still recombine with itself in females, the Y chromosome is allowed to degenerate. We will discuss how this all works next time as I still have to do more reading about the subject.
However, we can still discuss what I think is one of the most interesting phenomena I have encountered in evolutionary biology: evolutionary strata. Although strata are more of an X thing, it still relates to the Y enough for me to want to tell you about it, especially since it’s almost a new way of seeing time and history!
Genetic Components and Cultural Differences: The social sensitivity hypothesis
Cultural differences are often attributed to events far removed from genetics. The basis for this belief is often based on the assertion that if you take an individual, at birth, from one society and implant them in another, then they will generally grow up to become well-adjusted to their adopted culture. Whilst this is more than likely true, even if there may be certain cultural features that may disagree with someone of a different ethnic background (e.g. degrees of alcohol tolerance), the situation is not as clear cut as certain political factions may have you believe. Yet, largely due to studies on gene-culture coevolution, we are now starting to understand the complex dynamics through which genes and culture interact.
First, a particular culture may exert selection pressures on genes that provide an advantageous benefit to the adoption of a particular cultural trait. This is evident in the strong selection of the lactose-tolerance allele due to the spread of dairy farming. Second, pre-existing gene distributions provide pressures through which culture adapts. Off the top of my head, one proposed example of this is a paper by Dediu and Ladd (2007), which looked at how the distribution of the derived haplotypes of ASPM and Microcephalin may have subtly influenced the development of tonal languages. The paper in question, however, is looking more broadly at culture. Specifically, the authors, Baldwin May and Matthew Lieberman, examine recent genetic association studies and how within-variation of genes involved in central neurotransmitter systems are associated with differences in social sensitivity. In particular, they highlight a correlation between the relative frequencies of certain gene-variants and the relative degree of individualism or collectivism within certain populations.