Categorising languages through network modularity

Today I’ve been learning more about network structure (from Cris Moore) and I’ve applied my poor understanding and overconfidence to find language families from etymology data!

Here’s what I understand so far (see Clauset, Moore, &  Newman, 2008):  The modularity of a network is a measure of how many ‘communities’ it has.  An optimal modularity will split the graph to maximise the average degree within modules or clusters.  You can search all the possible clusterings to find this optimum.  I’m still hazy on how this is actually done, and you can extend this to find hierarchies like phylogenetics, but without some assumptions.  Luckily, there’s a network analysis program called gephi that does this automatically!

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Some Links #18: GxExC

The depression map: genes, culture, serotonin, and a side of pathogens. Another new science blog network (Wired) and once again a new stable of good science writers. I’m particularly pleased to see that David Dobbs, a former SciBling and top science writer, has found a new home for Neuron Culture. I was also pleased to see he had written an article on studies into the interactions between genes and culture, namely: Chiao & Blizinsky (2009) and Way & Lieberman (2010). And I was even more pleased to see that he’d mentioned both mine and Sean’s posts on the social sensitivity hypothesis. Suffice to say, I was pleased.

Take home paragraph:

In a sense, these studies are looking not at gene-x-environment interactions, or GxE, but at genes x (immediate) environment x culture — GxExC. The third variable can make all the difference. Gene-by-environment studies over the last 20 years have contributed enormously to our understanding of mood and behavior. Without them we would not have studies, like these led by Chiao and Way and Kim, that suggest broader and deeper dimensions to what makes us struggle, thrive, or just act differently in different situations. GxE is clearly important. But when we leave out variations in culture, we risk profoundly misunderstanding how these genes — and the people who carry them — actually operate in the big wide world.
Razib also has some thoughts on the topic:
The same issues are not as operative when it comes to culture. Two tribes can speak different dialects or languages. If a woman moves from one tribe to another her children don’t necessarily speak a mixture of languages, rather, they may speak the language of their fathers. The nature of cultural inheritance is more flexible, and so allows for the persistence of more heritable variation at different levels of organization. Differences of religion, language, dress, and values, can be very strong between two groups who have long lived near each other and may be genetically similar.

Homo was born vocalizing. Babel’s Dawn links to a recently finished PhD thesis that supposedly argues for a relatively recent emergence for language (approx. 120,000 years ago). She defends her assertions by stating: “[…] all of the unique cognitive traits attributed to humans arose as the consequence of one crucial mutation, which radically altered the architecture of the ancestral primate brain.” I haven’t read the thesis, and I probably won’t as I’m already stretched in regards to my reading, but I’m completely unconvinced by the hopeful mutation hypothesis. Plus, as Bolles notes in his post, there is plenty of available evidence to the contrary.

Primed for Reading. Robert Boyd reviews Stanislas Dehane’s new book, Reading in the Brain: The Science and Evolution of a Human Invention, which I’ll be picking up soon. In the meantime, to give you a bit of background, I suggest you read Dehane’s (2007) paper on the Neuronal Recycling Hypothesis: the Cultural recycling of cortical maps. H/T: Gene Expression.

Through the looking glass (part 1). The Lousy Linguist reviews Guy Deutscher’s new book, Through the Language Glass: Why the World Looks Different in Other Languages, with the general takeaway message being that, in part one at least, one where the book is a bit science-lite. What really interested me, though, were these two paragraphs:

We discover quite quickly what Deutscher is doing as he begins to walk through complexity issues of “particular areas of language” (page 109), namely morphology, phonology, and subordination. And these last 15 pages are really the gem of Part 1. He shows that there is an interesting, somewhat illogical, entirely engaging but as yet unexplained set of correlations between speaker population size and linguistic complexity.

For example, languages with small numbers of speakers tend to have more morphologically rich grammars (hence one could claim that small = more complex). However, small languages with small numbers of speakers also tend to have small phonological inventories. Hmmm, weird, right? [My emphasis]

As those of you who read this blog will know: I don’t think it’s weird that small speaker populations also tend to have small phonological inventories.

Clothing lice out of Africa. A cool new paper by Troups et al which looks at the evolutionary history of clothing lice to provide specific estimates on the origin of clothing. Using a Bayesian coalescent modelling approach, they estimate that clothing lice diverged from head louse ancestors between 83,000 and 170,000 years ago. H/T: Dienekes.

Where Are Memes?

This is more a public note to myself than anything else. It’s likely to seem a bit odd to those who haven’t been following my thinking on memes. Cross-posted at New Savanna.

Back in 1996 I published a long article, Culture as an Evolutionary Arena (link to downloadable PDF), in the, alas, now defunct, Journal of Social and Evolutionary Systems. In that article I introduced the notion of units of cultural inheritance with these paragraphs:

Following conversations with David Hays, I suggest that we regard the whole of physical culture as the genes: the pots and knives, the looms and cured hides, the utterances and written words, the ploughshares and transistors, the songs and painted images, the tents and stone fortifications, the dances and sculpted figures, all of it. For these are the things which people exchange with one another, through which they interact with one another. They can be counted and classified and variously studied.

What then of the ideas, desires, emotions, and attitudes behind these things? After all, as any college sophomore can point out, words on a page are just splotches unless apprehended by an appropriately prepared mind, one that knows the language. Pots and knives are not so ineffable as runes and ideograms, but they aren’t of much use to people who don’t know how to use them, that is, to people whose minds lack the appropriate neural “programs”. Surely, one might propose, these mental objects and processes are the stuff of culture.

What I in fact propose is that we think of these mental objects and processes as being analogous to the biologist’s phenotype just as the physical objects and processes are analogous to the genotype. Properly understood, these mental objects and processes are embodied in brain states (cf. Benzon and Hays 1988). Thus we have the whole of physical culture interacting with the inner cultural environment to produce the various mental objects and activities which are the substance of culture.

Richard Dawkins has proposed the term “meme” for the units of the cultural genotype, but proposes no special term for the cultural phenotype, though he recognizes the necessity of distinguishing the two (Dawkins 1982, pp. 109 ff., see also Dawkins 1989, pp. 189 ff.). Following more or less standard anthropological usage, I offer “psychological trait”, or just “trait”, as a term designating phenotypical units or features. Note, however, that Dawkins places memes in the brain and traits in the external world, which is just the opposite of what I am doing.

I have maintained that position until quite recently, say a week or two ago. I am now considering abandoning that conception. But first, a little more about how I further developed it.

In my 2001 book on music, Beethoven’s Anvil, I developed that idea with respect to music, arguing that the neural ‘trace’ (trajectory in neural state space) of musical performances is a cultural phenotype while the memes are those aspects of musical sound around which individuals coordinate their music-making activities. I further developed this idea only a few weeks ago in a series of posts I wrote as background to a post I did for the National Humanities Center on cultural evolution.

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Cultaptation Conference

Earlier this year I went along to the Cultaptation Conference at St Andrews. Despite being a fascinating event, there appears to nothing on the blogsphere pertaining to the speakers and their talks. In fact, this generally holds true for cultural evolution: there are no dedicated blogs reporting what is undoubtedly a serious scientific endeavour. As a remedy I’m going to dedicate several future blog posts to the conference. Until then, here are the talk abstracts for some of my personal highlights:

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