change – Page 3 – Replicated Typo

Genetic Anchoring, Tone and Stable Characteristics of Language

In 2007, Dan Dediu and Bob Ladd published a paper claiming there was a non-spurious link between the non-derived alleles of ASPM and Microcephalin and tonal languages. The key idea emerging from this research is one where certain alleles may bias language acquisition or processing, subsequently shaping the development of a language within a population of learners. Therefore, investigating potential correlations between genetic markers and typological features may open up new avenues of thinking in linguistics, particularly in our understanding of the complex levels at which genetic and cognitive biases operate. Specifically, Dediu & Ladd refer to three necessary components underlying the proposed genetic influence on linguistic tone:

[…] from interindividual genetic differences to differences in brain structure and function, from these differences in brain structure and function to interindividual differences in language-related capacities, and, finally, to typological differences between languages.”

That the genetic makeup of a population can indirectly influence the trajectory of language change differs from previous hypotheses into genetics and linguistics. First, it is distinct from attempts to correlate genetic features of populations with language families (e.g. Cavalli-Sforza et al., 1994). And second, it differs from Pinker and Bloom’s (1990) assertions of genetic underpinnings leading to a language-specific cognitive module. Furthermore, the authors do not argue that languages act as a selective pressure on ASPM and Microcephalin, rather this bias is a selectively neutral byproduct. Since then, there have been numerous studies covering these alleles, with the initial claims (Evans et al., 2004) for positive selection being under dispute (Fuli Yu et al., 2007), as well as any claims for a direct relationship between dyslexia, specific language impairment, working memory, IQ, and head-size (Bates et al., 2008).

A new paper by Dediu (2010) delves further into this potential relationship between ASPM/MCPH1 and linguistic tone, by suggesting this typological feature is genetically anchored to the aforementioned alleles. Generally speaking, cultural and linguistic processes will proceed on shorter timescales when compared to genetic change; however, in tandem with other recent studies (see my post on Greenhill et al., 2010), some typological features might be more consistently stable than others. Reasons for this stability are broad and varied. For instance, word-use within a population is a good indicator of predicting rates of lexical evolution (Pagel et al., 2007). Genetic aspects, then, may also be a stabilising factor, with Dediu claiming linguistic tone is one such instance:

From a purely linguistic point of view, tone is just another aspect of language, and there is no a priori linguistic reason to expect that it would be very stable. However, if linguistic tone is indeed under genetic biasing, then it is expected that its dynamics would tend to correlate with that of the biasing genes. This, in turn, would result in tone being more resistant to ‘regular’ language change and more stable than other linguistic features.

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Memory, Social Structure and Language: Why Siestas affect Morphological Complexity

Children are better than adults at learning second languages. Children find it easy, can do it implicitly and achieve a native-like competence. However, as we get older we find learning a new language difficult, we need explicit teaching and find some aspects difficult to master such as grammar and pronunciation. What is the reason for this? The foremost theories suggest it is linked to memory constraints (Paradis, 2004; Ullman, 2005). Children find it easy to incorporate knowledge into procedural memory – memory that encodes procedures and motor skills and has been linked to grammar, morphology and pronunciation. Procedural memory atrophies in adults, but they develop good declarative memory – memory that stores facts and is used for retrieving lexical items. This seems to explain the difference between adults and children in second language learning. However, this is a proximate explanation. What about the ultimate explanation about why languages are like this?

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Bleg: Why CULTURAL Evolution?

That is to ask: Why has there been so much interest in cultural evolution in the last two decades or so? It seems to me that a lot of this thinking is just messing around, seeing if evolutionary ideas can somehow be attached to cultural phenomena in a coherent way. It seems more motivated by a desire to extend evolutionary thinking than by a desire to understand culture. And it’s not obvious to me that anyone has actually explained anything in this process, not so far.

In particular, has anyone used some theory of cultural evolution to explain some phenomenon of culture as well as, and ideally, better than competing non-evolutionary accounts? It’s not at all obvious to me that the answer to that question is “Yes.”

Note that I don’t exempt my own efforts from this criticism, which is why, on the whole, I’ve devoted more time to examining and analyzing cultural phenomenon than I have conceptualizing cultural evolution. In particular, I’ve spent a lot of time thinking about popular music in America, and the interaction of African-derived and European-derived styles (see, e.g. this longish paper) and, more recently, I’ve been looking at graffiti, which I’ll address later on.

Evolution?

One caveat: A lot depends on just what one means by cultural evolution. If one is just using ‘evolution’ as a substitute for ‘change,’ then the question has little meaning. It seems to me that much of memetics is like this, with the added innovation of attributing agency to the memes, rather than to people.

And then there’s gene-cultural coevolution (GCCE). Those folks may well have succeeded in coming up with useful explanations, e.g. lactose tolerance. But it’s not at all clear to me that GCCE can work with the kinds of phenomena that most interest me and that do constitute a great deal of cultural activity. As I’ve explained here, it’s not clear to me that GCCE has anything to say, for example, about something like the growth of graffiti in the last 40 years.

Graffiti 1

By ‘graffiti’ I don’t mean any writing on walls, but the specific practice that originated on the East Coast of the USA in Philadelphia and New York City in the late 1960s and early 1970s. The practice seems to have been pretty much confined to those cities by the early 1980s. But it had gone world-wide by the start of the current millennium. How did that happen? And why?

I don’t see that GCCE has any tools to answer that question. The spread is too fast for any biological changes to have been involved. Whatever’s going on has been going on purely within the cultural sphere. There are obvious things to point to concerning how it happened: 1) Press coverage of early graffiti made the activity more visible. 2) When graffiti became associated with hip-hop, it followed hip-hop in its spread through world pop culture. 3) Photography, books, and films (Style Wars, Wild Style) spread the word. 4) The emergence of the world-wide-web created a new means by which photos of graffiti could made instantly available around the world.

But none of that explains why the practice spread. What made graffiti so attractive to so many people in so many different places around the world? And why has it been, on the whole, so conservative, so that the themes and motifs that originated in the East Coast of the USA in the late 1970s and early 1980s are showing up in Japan in then 2000s? On one level that question answers itself. If the designs changed rapidly, so that putting any old design up on the walls counted as graffiti, then the activity would loose its identity, its genealogical connection with those first writers in New York City and Philadelphia. It would just be painting on walls, illegally. Big deal.

The genealogical connection IS important. Why? Note that, while stylistic conservatism maintains that identity, we also have to allow for the identity of individual writers within the tradtion. The tradition has to have enough internal variety to allow for that.

There are ways of talking about those questions, and you’ll find some of them in the literature, but the question I’m asking is this: Can a strong theory of cultural evolution do a better job of accounting for this spread than any other theory? If so, what would that theory look like?

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A history of evolution pt. 2: The Wealth of Nations, Populations and On the Origin

An_Essay_on_the_Principle_of_Population — Title page of the original edition of Malthus' 1798 work

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More on Phoneme Inventory Size and Demography

On the basis of Sean’s comment, about using a regression to look at how phoneme inventory size improved as geographic spread was incorporated along with population size, I decided to look at the stats a bit more closely (original post is here). It’s fairly easy to perform multiple regression in R, which, in the case of my data, resulted in highly significant results (p<0.001) for the intercept, area and population (residual standard error = 9.633 on 393 degrees of freedom; adjusted R-Squared = 0.1084). I then plotted all the combinations as scatterplots for each pair of variables. As you can see below, this is fairly useful as a quick summary but it is also messy and confusing. Another problem is that the pairs plot is on the original data and not the linear model.

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Evolution of Colour Terms: 10 Universal Patterns are not Evidence for Innate Constraints

In a series of posts, I’ve been discussing constraints on the evolution of colour terms. Here, I discuss the role of drift and also argue that universal patterns are not necessarily good evidence for innate constraints. For the full dissertation and references, go here.

Drift

An important point which has not been highlighted in the literature is the drift introduced by cultural transmission. Perceptual systems are noisy, and change over lifetimes. Therefore, systems of categorising these perceptions may drift over time. However, if concepts are shared, this drift is influenced by more than one system. This may cause a different kind of drift from a stand-alone system for self-thought. Communication has an additional semantic bottleneck which self-though does not have. Using language for self thought, if you don’t know a label, you can make one up.

However, for communication, this won’t work. For example, in models of cultural transmission (e.g., Steels & Belpaeme, 2005) agents do create new labels but, importantly, accept the speaker’s label when available. That is, communicative systems are more flexible than systems for self-thought (communicators must be more willing to change their minds), and so are more subject to drift. The drift allows the system to move around the possible space of coding efficiency and object categorisation efficiency. Peaks in these landscapes will attract the drift, hence environmental and perceptual constraints being projected into language.

Although systems of colour categorisation for self-thought may be more efficient if they were constrained by the environment, shared cultural systems are more likely to reflect constraints in the environment because they are more flexible. That is, perceptual constraints have projected themselves into language because of a communicative pressure, rather than a perceptual or environmental pressure.

I suggest that this drift, together with an ability for categories to warp perceptual spaces, would mean that individuals converge on a shared perceptual system. If comprehension involves the activation of perceptual representations, then communication involves individuals reaching similar perceptual representations or, in a perfect world, activation of the same neural substrates. Therefore, a population with a shared perceptual system would be able to communicate much more effectively. In this sense, Embodied systems improve communicative success, whereas the same effect is not necessarily true of Symbolist systems. Furthermore, this drift means that populations can still converge on similar solutions, without having to assume that Universal biases are the main driving force. It has been argued that the similarities in colour categorisation between cultures contradicts Relativism, which would predict a large variation in colour categorisation between cultures (e.g., Belpaeme & Bleys, 2005). I argue that this inference is not necessarily valid.

Summary

This series of posts has shown that a wide range of factors constrain the categorisation of colour, including the physiology of perception, the environment and cultural transmission. Why is there evidence for Colour Terms being adapted to so many domains?

This study considered the idea that categorisation acquired by individuals can feed back into perception and itself become a constraint both on the development of categorisation, the environment and genetic inheritance. In this sense, the feedback from categorisation allows Niche Construction dynamics to apply to linguistic categorisations. It was argued that this dynamic fits with the Cultural implication of an Embodied account of language comprehension. That is, this study has concluded, similarly to Kirby et al. (2007), that universal patterns across populations do not necessarily imply strong innate biases. This was done by arguing that Cultural, Embodied systems tend to drift towards better representations of the real world, which involves better coherence with perceptual and environmental constraints, creating cross-cultural patterns. Furthermore, an Embodied approach to cultural dynamics incorporating a mechanism for perceptual warping predicts that the perceptual spaces of individuals can be synchronised through language to achieve better communication.

Steels, L., & Belpaeme, T. (2005). Coordinating perceptually grounded categories through language: A case study for colour Behavioral and Brain Sciences, 28 (04) DOI: 10.1017/S0140525X05000087

Belpaeme, T. (2005). Explaining Universal Color Categories Through a Constrained Acquisition Process Adaptive Behavior, 13 (4), 293-310 DOI: 10.1177/105971230501300404

Kirby, S., Dowman, M., & Griffiths, T. (2007). Innateness and culture in the evolution of language Proceedings of the National Academy of Sciences, 104 (12), 5241-5245 DOI: 10.1073/pnas.0608222104

Evolution of Colour Terms: 9 Niche Construction

In a series of posts, I’ve been discussing constraints on the evolution of colour terms. For the full dissertation and references, go here.

This section reiterates how a link between linguistic categories and perception fits into Niche Construction Theory. If concepts can influence perception, and people share the same concepts, their perceptions will become synchronised. This would render them more effective at communication, since referents would be perceived as similar (‘red’ can refer to the same domain of entities for each individual). Furthermore, it may render them more able to co-operatively build a better model of the actual environment (for instance, describing an unseen danger, or researching physics). However, this will only be true if language is grounded in constraints that come from the actual environment. If this were not the case, apart from being inefficient at describing the actual environment, a language may drift to influence the perceived environment in a way that results in a worse fit with the actual environment.

Returning to the constraints diagram (above), note that the influence of categorisation continues, through action, to change the environment. In other words, if language influences the perceived environment and facilitates communication, then it may also facilitate the way we change the actual environment. In this sense, language’s influence on perception can be regarded as a form of Niche Construction (Laland, Odling-Smee & Feldman, 2000). Therefore, not only does language become better at describing the actual environment, but the environment becomes better suited to being described by language. This creates a better fit between perceived and actual environments and possibly increases the fitness of language users. Essentially, then, this study presents evidence for language-specific niche construction where language can influence the environment. This dynamic would be a consequence of an Embodied system, and more efficient as part of an Embodied system than a Symbolist account. I therefore argue that the Embodied account is supported.

As an example of this dynamic, Hansen et al. (2006) showed that perception is affected by semantic knowledge, specifically that achromatic bananas look yellow. However, bananas are domesticated (Heslop-Harrison & Schwarzacher, 2007). The link between a banana’s structure and colour, therefore, is a constructed niche – cultivators fertilise the ‘best’ bananas, which go on to influence the way they perceive bananas, which affects which bananas they fertilise, and so on. This means that the effect found in Hansen et al. cannot be innate, since the colour and structure of a banana have changed (see below). Modulating perception with flexible, high-level categories is a way of keeping up with rapidly changing environments.

Differing structures and colours of six species of banana, all ripe. Top left: Musa balbisiana, ancestor of modern cultivated bananas. Top right: Pink Banana (Musa velutina). Bottom, from left to right: Plantains (Musa paradisiacal), red bananas (Musa rutilus), Bananito (Musa acuminate) and Cavendish bananas (Musa cavendishii). Images from Wikimedia Commons, http://commons.wikimedia.org

Less anecdotally, Griffin’s (2006) model, which classified objects using colour (see section 5.2.2), found that natural colour categories optimally aid the identification of objects. Furthermore, the model performed equally well for natural and manufactured objects. That is, manufactured objects have been coloured to be maximally classifiable by colour, according to linguistic colour categorisations. This would be an intuitive and efficient tactic if, as Embodied Cognition suggests, comprehension is scaffolded onto systems of object recognition (MacWhinney, 1999). There would be no advantage in doing this in a Symbolist system where perceptions and concepts have arbitrary connections.

Next, why universal patterns are not evidence for innate constraints ->

Laland, K., Odling-Smee, J., & Feldman, M. (2000). Niche construction, biological evolution, and cultural change Behavioral and Brain Sciences, 23 (1), 131-146 DOI: 10.1017/S0140525X00002417

Hansen, T., Olkkonen, M., Walter, S., & Gegenfurtner, K. (2006). Memory modulates color appearance Nature Neuroscience, 9 (11), 1367-1368 DOI: 10.1038/nn1794

Heslop-Harrison, J., & Schwarzacher, T. (2007). Domestication, Genomics and the Future for Banana Annals of Botany, 100 (5), 1073-1084 DOI: 10.1093/aob/mcm191

Griffin, L. (2004). Optimality of the Basic Colours Categories Journal of Vision, 4 (8), 309-309 DOI: 10.1167/4.8.309

New Blog: Culture Evolves!

… Well, new to me at least. It’s run by Fiona Jordan of the Max Planck Institute for Psycholinguistics, and her latest post is an interview with one of my favourite researchers, Simon Greenhill (I didn’t know he designed a sudoku solving program). Also, after having done a little digging into her publications, I found the following forthcoming paper: The effect of population size and density on rates of linguistic evolution. Here is the abstract:

Evolutionary theory from population genetics predicts that demography may play an important role in determining the rate at which cultural and linguistic traits change over time. However, relatively few studies have explored this relationship for language at an appropriate scale and in a quantitative way, nor controlled for the problem of non-independence induced by the historical relationships between languages. Here we use phylogenetic trees of 351 Austronesian languages to test whether the rate of change in core vocabulary is affected by population size and population density. We detected a strong phylogenetic signal in both population size and density, indicating the need for historical control. We find a significant inverse relationship between lexical replacement and population size, no relationship with population density, and we confirm that splitting events influence lexical evolution. These results support the idea that a process analogous to genetic drift may be an important factor in lexical evolution. Furthermore, the strong phylogenetic signal in these demographic factors suggests that despite repeated population splits the social conditions that influence speech community size and density are maintained and inherited from one generation to the next.

I’m not going to say anything on a paper I haven’t yet read, other than it looks pretty cool and that more people should be considering the influence of demographic factors in linguistics.

Evolution of Colour Terms: 1 Genetic Constraints

Continuing my series on the Evolution of Colour terms, this post reviews the evidence for genetic constrains on colour perception. For the full dissertation and for references, go here.

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Evolution of Colour Terms: Part 1

In a series of posts, I’ll review the current state of the field of the Evolution of Colour Categories. It has been argued that universals in colour naming across cultures can be traced back to constraints from many domains including genetic, perceptual and environmental. I’ll review these arguments and show that if our perception is affected by our language, then many conflicts can be resolved. Furthermore, it undermines the Universalist assumption that universal patterns in colour terms are evidence for innate constraints.

Part 1: Domains of Constraint

Genetic Constraints

Environmental Constraints

Perceptual Constraints

Learning Constraints

Cultural Constraints

Categorisation Constraints

Part 2: Universal patterns are not evidence for innate constraints

Perceptual Warping

Embodied Relationships

Niche Construction

Universal Patterns are not Evidence for Innate Constraints