Tag: linguistics

Can linguistic features reveal time depths as deep as 50,000 years ago?

ResearchBlogging.orgThroughout much of our history language was transitory, existing only briefly within its speech community. The invention of writing systems heralded a way of recording some of its recent history, but for the most part linguists lack the stone tools archaeologists use to explore the early history of ancient technological industries. The question of how far back we can trace the history of languages is therefore an immensely important, and highly difficult, one to answer. However, it’s not impossible. Like biologists, who use highly conserved genes to probe the deepest branches on the tree of life, some linguists argue that highly stable linguistic features hold the promise of tracing ancestral relations between the world’s languages.

Previous attempts using cognates to infer the relatedness between languages are generally limited to predictions within the last 6000-10,000 years. In the present study, Greenhill et al (2010) decided to examine more stable linguistic features than the lexicon, arguing:

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Recent Abstracts #1

In an effort to update this blog regularly, I’ve decided to take the lazy route and post up a list of abstracts. This will only happen once a week, but it’s a useful resource (for me at least), and will usually be an indicator of what articles I’m going to write about in the near future.

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Answering Wallace's challenge: Relaxed Selection and Language Evolution

ResearchBlogging.orgHow does natural selection account for language? Darwin wrestled with it, Chomsky sidestepped it, and Pinker claimed to solve it. Discerning the evolution of language is therefore a much sought endeavour, with a vast number of explanations emerging that offer a plethora of choice, but little in the way of consensus. This is hardly new, and at times has seemed completely frivolous and trivial. So much so that in the 19th Century, the Royal Linguistic Society in London actually went as far as to ban any discussion and debate on the origins of language. Put simply: we don’t really know that much. Often quoted in these debates is Alfred Russell Wallace, who, in a letter to Darwin, argued that: “natural selection could only have endowed the savage with a brain a little superior to that of an ape whereas he possesses one very little inferior to that of an average member of our learned society”.

This is obviously relevant for those of us studying language evolution. If, as Wallace challenged, natural selection (and more broadly, evolution) is unable to account for our mental capacities and behavioural capabilities, then what is the source behind our propensity for language? Well, I think we’ve come far enough to rule out the spiritual explanations of Wallace (although it still persists on some corners of the web), and whilst I agree that biological natural selection alone is not sufficient to explain language, we can certainly place it in an evolutionary framework.

Such is the position of Prof Terrence Deacon, who, in his current paper for PNAS, eloquently argues for a role for relaxed selection in the evolution of the language capacity. He’s been making these noises for a while now, as I previously mentioned here, with him also recognising evolutionary-similar processes in development. However, with the publication of this paper I think it’s about time I disseminated his current ideas in more detail, which, in my humble opinion, offers a more nuanced position than the strict modular adaptationism previously championed by Pinker et al (I say previously, because Pinker also has a paper in this issue, and I’m going to read it before making any claims about his current position on the matter).

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Phylogenetics, Cultural Evolution and Horizontal Transmission

ResearchBlogging.orgFor some time now, evolutionary biologists have used phylogenetics. It is a well-established, powerful set of tools that allow us to test evolutionary hypotheses. More recently, however, these methods are being imported to analyse linguistic and cultural phenomena. For instance, the use of phylogenetics has led to observations that languages evolve in punctuational bursts, explored the role of  population movements, and investigated the descent of Acheulean handaxes. I’ve followed the developments in linguistics with particular interest; after all, tracing the ephemeral nature of language is a daunting task. The first obvious road block is that prior to the invention of writing, the uptake of which is limited in geography and history, language leaves no archaeological record for linguists to examine. One particular note I’d like to make is that when Charles Darwin first formulated his theory of natural selection, he took inspiration from linguistic family trees as the basis for his sketch on the evolutionary tree of life. So it seems rather appropriate that phylogenetic approaches are now being used to inform our knowledge regarding linguistic evolution.

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Broca's Area and Hierarchical Structure Building

Considering I devoted two blog posts (pt.1 & pt.2) to Broca’s area and its role in processing hierarchically organised sequences, I’m happy report the following from a Talking Brains post on Disentangling syntax and intelligibility:

Hierarchical structure building can be achieved without Broca’s area involvement.

I’ve only just finished reading the post and, despite having some thoughts on the topic, I’m going to read the actual paper in question (Disentangling syntax and intelligibility in auditory language comprehension) before commenting. Especially since the authors, Friederici et al, don’t seem to arrive at the same conclusions as the bloggers over at Talking Brains. Still, as far as I can tell, this is only looking at syntactic information within speech, and doesn’t really tell us anything about the processing of hierarchically organised sequences in other linguistic (e.g. written language) and non-linguistic (e.g. tool manufacturing) domains.

Here’s the abstract for the paper in question:

Studies of the neural basis of spoken language comprehension typically focus on aspects of auditory processing by varying signal intelligibility, or on higher-level aspects of language processing such as syntax. Most studies in either of these threads of language research report brain activation including peaks in the superior temporal gyrus (STG) and/or the superior temporal sulcus (STS), but it is not clear why these areas are recruited in functionally different studies. The current fMRI study aims to disentangle the functional neuroanatomy of intelligibility and syntax in an orthogonal design. The data substantiate functional dissociations between STS and STG in the left and right hemispheres: first, manipulations of speech intelligibility yield bilateral mid-anterior STS peak activation, whereas syntactic phrase structure violations elicit strongly left-lateralized mid STG and posterior STS activation. Second, ROI analyses indicate all interactions of speech intelligibility and syntactic correctness to be located in the left frontal and temporal cortex, while the observed right-hemispheric activations reflect less specific responses to intelligibility and syntax. Our data demonstrate that the mid-to-anterior STS activation is associated with increasing speech intelligibility, while the mid-to-posterior STG/STS is more sensitive to syntactic information within the speech.

Some links #1

Having now returned, I feel a long list of links is needed to kick start things:

Right, that’s all I’ve got time for at the moment. Laptop battery is dying and my bladder is urging me towards the toilet.

The arcuate fasciculus within the dual stream model pt.2

ResearchBlogging.org3.1 What is the dual stream model?

Given these separate anatomical accounts, attributing a function(s) to the arcuate is not clear cut, and any current account is far from the authoritative statement on the matter. Nonetheless, a vast majority of literature does place the arcuate as part of the dual stream model[1] of speech processing, although its exact role within these neural networks is still being disputed – and largely depends on which anatomical account you prescribe to.

The basic assumption of dual stream accounts is that phonological networks interact with both conceptual-semantic and motor-articulatory systems, leading to a distinction between the neural networks that process this speech information. These separate interactions are summarised under two processing streams: the dorsal stream and the ventral stream (Hickok and Poeppel, 2007). Connecting phonological networks with conceptual-semantic systems, using structures in the superior and middle portions of the temporal lobe, is the ventral stream. Meanwhile, the dorsal stream is linked via structures in the posterior frontal lobe to the posterior temporal lobe and parietal operculum, which connects phonological networks with motor-articulatory systems (ibid).

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Inconsistent, yes… But here are some links.

Okay, I promised a post a day and failed miserably. But it does say in my profile that I’m inconsistent. So it’s probably best to not believe everything I write, even if there is one valuable lesson in my broken promises: avoid targets. Anyway, I just thought I’d do a quick post on some articles that have caught my attention over the past few days:

Some changes

Now I’ve had a month-long break from blogging you may, or may not, have noticed a few changes to the blog, notably the inclusion of three additional features: Dissertation, Minifeed and Basic Concepts. So from now on in, I will definitely be adding a post every day, and hopefully a research-related post every week or so. But before all this happens, I really suggest you go over and visit Babel’s Dawn, as Mr Bolles is putting much of us slightly less prolific bloggers to shame with his coverage of the ways to protolanguage conference.

As for my own opinion of protolanguage: yes, it probably existed, but I really haven’t got any more to add at the moment. It is a topic I plan on returning to in another post, although I’m not really sure I can add anything extra to the current debate. There is one thing, though: I do find debates on concerning the transition of protolanguage into a fully fledged language a bit tiresome. I mean we’re not even fully sure as to the impact that writing systems have had on how we speak. Take Chomsky’s favourite topic of recursion. As far as I know, there is no evidence of complex recursion being present in languages prior to the emergence of writing systems. It may be the case that writing allowed for languages with no, or very circumscribed, recursion in their syntax to develop into a system that allows for embedding of indefinite complexity.

In truth, you can argue many features of language didn’t appear until the development of writing, as there is no solid record of languages existing prior to this invention. This is a problem all linguists face, and it does require a lot of assumptions to be made beforehand — some of which are reasonable (languages did exist before writing) and some of which may be construed as not reasonable (literate societies process language in the same way as non-literate societies).

Discerning the role of the arcuate fasciculus in speech processing pt.1

ResearchBlogging.orgOriginally identified by Reil (1809) and subsequently named by Burdach (1819), the arcuate fasciculus is a white-matter, neural pathway that intersects with both the lateral temporal cortex and frontal cortex via a “dorsal projection that arches around the Sylvain fissure.” (Rilling et al., 2008, pg. 426). Classical hypotheses saw this pathway as a critical component in connecting two centres of language: Broca’s area (speech production) and Wernicke’s area (speech comprehension) (Catani and Mesulam, 2008).

Much of these assumptions were based on a tentative relationship between language-impairment and damaged portions of the brain. Notably, damage to the arcuate fasciculus is implicated in a syndrome known as conduction aphasia, where an individual has difficulty in speech repetition. Often characterised by errors in spontaneous speech, an individual with conduction aphasia will be fully aware of their mistake, retaining well-preserved auditory comprehension and speech production while also being syntactically and grammatically correct (ibid).

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