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Everett, Pirahã and Recursion: The Latest

February 1, 2012 in Evolution, Genetics, Linguistics

Discussing the concept of recursion is like a rite of passage for anyone interested in language evolution: you go through it once, take a position and hope it doesn’t come back to haunt you.  As Hannah pointed out last year, there are two definitions of recursion:

(1) embeddedness of phrases within other phrases, which entails keeping track of long-distance dependencies among phrases;

(2) the specification of the computed output string itself, including meta-recursion, where recursion is both the recipe for an utterance and the overarching process that creates and executes the recipe.

The case of grammatical recursion (see definition 1) is perhaps most famously associated with Noam Chomsky. Not only does he claim all human languages are recursive, but also that this ability is biologically hardwired as part of our genetic makeup. Countering Chomsky’s first claim is the debate surrounding a small Amazonian tribe called the Pirahã: even though they show signs of recursion, such as the ability to recursively embed structures within stories, the Pirahã grammar is claimed not to recursively embed phrases within other phrases. If true, then are numerous implications for a wide variety of fields in linguistics, but this is still an unsubstantiated claim: for the most part, we are relying on one specific researcher (Daniel Everett) who, despite having dedicated a large portion of his life to studying the tribe, could very well have been misled. That said, I retain a large amount of respect for Everett, having watched him speak at Edinburgh a few years ago and read his book on the topic: Don’t Sleep, There are Snakes: Life and Language in the Amazonian Jungle.

So, why am I rambling on about recursion? Well, besides its obvious relevance, — and perhaps under-representation on this blog (deserved or not, I’ll let you decide) — Everrett has recently published a series of slides about a corpus study of Pirahã grammar (see below).

Download (PDF, 841.58KB)

His tentative conclusion: there is no strong evidence for recursion among relative clauses, complement clauses, possessive structures and conjunctions/disjunctions. However, there is possible evidence of recursive structure in topics/repeated arguments. He also posits cultural pressures for longer or shorter sentences, such as writing systems (as I mentioned way back in 2009).

I’m sure this debate will be brought to the fore at this year’s EvoLang, with Chomsky Berwick Piattelli-Palmarini and many of the Biolinguistic crowd in attendance, and it’s a shame I’ll almost certainly miss it (unless someone wants to pay for my ticket… Just hit the donate button in the left-hand corner ;-) ).

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Animal Cognition & Consciousness (II): Metacognition & Mentalizing

January 12, 2012 in Evolution, Science

As I wrote in my last post, three kinds of behaviours are most often discussed in debates about animal consciousness and cognition:

“1. Mirror self-recognition

2. Tests of metacognition;

3. Metacognition of others’ mental states” (Gómez 2009: 45)

After having discussed the first capacitiy in my previous post, I will discuss the latter two in this post, starting with metacognition, that is being aware of one’s own knowledge states, and then turn to being aware of other’s mental states.

Metacognition.

Being aware of one’s own mental states, i.e., reflective consciousness, surely seems to be one of the most crucial components of self-awareness. In one paradigm used to test for metacognitive awareness, monkeys were trained to select, out of a number of two or more images, the one that is identical to an image they have been shown earlier. As is to expected, the monkeys’ performance progressively deteriorated the longer the delay was between the sample image and the selection task.

 

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Animal Cognition & Consciousness (I): Mirror Self-Recognition

January 8, 2012 in Evolution, Science

Darwin made a mistake. At least that is what Derek Penn and his colleagues (2008) claim in a recent and controversial paper in Behavioral and Brain Sciences. Darwin (1871) famously argued that the difference between humans and animals was “one of degree, not of kind.”

This, according to Penn et al. is of course true from an evolutionary perspective, but in their view,

“the profound biological continuity between human and nonhuman animals masks an equally profound discontinuity between human and nonhuman minds” (Penn et al. 2008: 109).

They hold that humans are not simply smarter, but human cognition differs fundamentally and qualitatively from that of other animals.

One pervasive proposal is that we do not simply possess a unique set of cognitive capacities, but that it might be consciousness itself that is uniquely human as well, a view that goes back at least to Descartes (Burkhardt & Bekoff 2009: 41). However, there are also many scholars and researchers who agree that there is evidence for higher-order cognition in nonhuman animals ( ‘animals’ after this) and that they might possess at least some degree of consciousness (Burkhard & Bekoff 2009: 40f.).

In this and my next post, I will write about three kinds of phenomena that are most often discussed in debates on whether animals have some form of higher-order cognition and consciousness or not: self-awareness, awareness of one’s own cognitive states, and awareness of others’ cognitive states and intentions.

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Social structure and language evolution: resolving the synthetic/analytic debate

January 3, 2012 in Evolution

A cultural evolution approach to language suggests that genes encode weak prior biases that can be amplified through cultural transmission to produce strong language universals.  Below is a diagram from Kirby, Dowman & Griffiths (2007).

The link between biological predispositions and language structure, from Kirby, Dowman & Griffiths, 2007.

Note the long-term feedback between language universals and genes.  However, recent research is pointing towards a more complicated picture.  Read the rest of this entry →

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Deictic Gestures in Ravens

December 7, 2011 in Abstracts, Evolution

Guys! Guys! Guys!

Ravens can point. It’s scary how clever birds can be. People keep sending me this paper so I thought I’d link to it here so that people know I’ve seen it and stop bothering me (I actually don’t mind being bothered, especially if it’s about interesting things like this, please don’t stop). Abstract below.

Around the age of one year, human children start to use gestures to coordinate attention towards a social partner and an object of mutual interest. These referential gestures have been suggested as the foundation to engage in language, and have so far only been observed in great apes. Virtually nothing is known about comparable skills in non-primate species. Here we record thirty-eight social interactions between seven raven (Corvus corax) dyads in the Northern Alps, Austria during three consecutive field seasons. All observed behaviours included the showing and/or offering of non-edible items (for example, moss, twigs) to recipients, leading to frequent orientation of receivers to the object and the signallers and subsequent affiliative interactions. We report evidence that the use of declarative gestures is not restricted to the primate lineage and that these gestures may function as ‘testing-signals’ to evaluate the interest of a potential partner or to strengthen an already existing bond.

If you’re interested in reading about referencial gestures in humans and chipanzees and why these things are relevant to the evolution of language you should read Michael’s post here.

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Reconstructing linguistic phylogenies – a tautology?

November 25, 2011 in Evolution, Linguistics, Science

ResearchBlogging.org

So I thought I should begin my first post on here with a nice and gentle introductory sentence, but I realise that pointing out the increased use of computational phylogenetic tools on cultural and particularly linguistic data to the avid readers of this blog is probably a pretty pointless exercise.

There is of course a lot to say about parallels between biological and cultural evolution, and some of the work using computational tools has given us new insights into yet unanswered (and even hitherto unasked!) questions regarding language and language change. But today I’d like to share some thoughts on a particular “application” of phylogenetic tools, the methodology of which I find a bit odd, even though it is arguably the simplest evolutionary analogy of them all: using computational phylogenetics to reconstruct linguistic phylogenies.

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James Hurford: Animals Do Not Have Syntax (Compositional Syntax, That Is)

October 30, 2011 in Evolution, Science, Uncategorized

After passing my final exams I feel that I can relax a bit and have the time to read a book again. So instead of reading a book that I need to read purely for ‘academic reasons’, I thought I’d pick one I’d thoroughly enjoy: James Hurford’s “The Origins of Grammar“, which clocks in at a whopping 808 pages.
I’m still reading the first chapter (which you can read for free here) but I thought I’d share some of his analyses of “Animal Syntax.”
Hurford’s general conclusion is that despite what you sometimes read in the popular press,

“No non-human has any semantically compositional syntax, where the form of the syntactic combination determines how the meanings of the parts combine to make the meaning of the whole.”

The crucial notion here is that of compositionality. Hurford argues that we can find animal calls and songs that are combinatorial, that is songs and calls in which elements are put together according to some kind of rule or pattern. But what we do not find, he argues, are the kinds of putting things together where the elements put together each have a specified meaning and the whole song, call or communicative assembly “means something which is a reflection of the meanings of the parts.”

(Link)
To illustrate this, Hurford cites the call system of putty-nosed monkeys (Arnold and Zuberbühler 2006). These monkeys have only two different call signals in their repertoire, a ‘pyow’-sound that ‘means’, roughly, ‘LEOPARD’; and a ‘hack’ sound that ‘means’, roughly, ‘EAGLE’.

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Degeneracy, Evolution and Language

September 22, 2011 in Evolution, Linguistics, Science

Having had several months off, I thought I’d kick things off by looking at a topic that’s garnered considerable interest in evolutionary theory, known as degeneracy. As a concept, degeneracy is a well known characteristic of biological systems, and is found in the genetic code (many different nucleotide sequences encode a polypeptide) and immune responses (populations of antibodies and other antigen-recognition molecules can take on multiple functions) among many others (cf. Edelman & Gally, 2001). More recently, degeneracy is appreciated as having applications in a wider range of phenomena, with Paul Mason (2010) offering the following value-free, scientific definition:

Degeneracy is observed in a system if there are components that are structurally different (nonisomorphic) and functionally similar (isofunctional) with respect to context.

A pressing concern in evolutionary research is how increasingly complex forms “are able to evolve without sacrificing robustness or the propensity for future beneficial adaptations” (Whitcare & Bender, 2010). One common solution is to refer to redundancy: duplicate elements that have a structure-to-function ratio of one-to-one (Mason, 2010). Nature does redundancy well, and is exemplified by the human body: we have two eyes, two lungs, two kidneys, and so on. Still, even with redundant components, selection in biological systems would result in a situation where competitive elimination leads to the eventual extinction of redundant variants (ibid).

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Cooperation and Conflict Colloqium papers

June 24, 2011 in Abstracts, Evolution

Papers from the “In the Light of Evolution V:  Cooperation and Conflict” edition of the Sackler Colloquium are now available in the early edition of PNAS:

http://www.pnas.org/search?tocsectionid=In+the+Light+of+Evolution+V:+Cooperation+and+Conflict+Sackler+Colloquium&sortspec=date&submit=Submit

Some papers such as “The cultural niche: Why social learning is essential for human adaptation”, “Genomic imprinting and the evolutionary psychology of human kinship” and “Evolutionary foundations of human prosocial sentiments” may be of interest to the reader of the blog.

 

You can read the earlier “In the light of Evolution” collections here:

In the Light of Evolution IV: The Human Condition: http://www.pnas.org/content/107/suppl.2

In the Light of Evolution III: Two Centuries of Darwin: http://www.pnas.org/content/106/suppl.1

In the Light of Evolution II: Biodiversity and Extinction: http://www.pnas.org/content/105/suppl.1

In the Light of Evolution I: Adaptation and Complex Design: http://www.pnas.org/content/vol104/suppl_1/

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Laryngeal Air Sacs

June 8, 2011 in Abstracts, Academia, Evolution, Science

So, I got a request from a friend of mine to make an abstract on the fly for a poster for Friday. I stayed up until 3am and banged this out. Tonight, I hope to write the poster justifying it into being. A lot of the work here builds on Bart de Boer’s work, with which I am pretty familiar, but much of it also started with a wonderful series of posts over on Tetrapod Zoology. Rather than describe air sacs here, I’m just going to link to that – I highly suggest the series!

Here’s the abstract I wrote up, once you’ve read that article on air sacs in primates. Any feedback would be greatly appreciated – I’ll try to make a follow-up post with the information that I gather tonight and tomorrow morning on the poster, as well.

Re-dating the loss of laryngeal air sacs in hominins

Laryngeal air sacs are a product of convergent evolution in many different species of primates, cervids, bats, and other mammals. In the case of Homo sapiens, their presence has been lost. This has been argued to have happened before Homo heidelbergensis, due to a loss of the bulla in the hyoid bone from Austrolopithecus afarensis (Martinez, 2008), at a range of 500kya to 3.3mya. (de Boer, to appear). Justifications for the loss of laryngeal air sacs include infection, the ability to modify breathing patterns and reduce need for an anti-hyperventilating device (Hewitt et al, 2002), and the selection against air sacs as they are disadvantageous for subtle, timed, and distinct sounds (de Boer, to appear). Further, it has been suggested that the loss goes against the significant correlation of air sac retention to evolutionary growth in body mass (Hewitt et al., 2002).

I argue that the loss of air sacs may have occurred more recently (less than 600kya), as the loss of the bulla in the hyoid does not exclude the possibility of airs sacs, as in cervids, where laryngeal air sacs can herniate between two muscles (Frey et al., 2007).  Further, the weight measurements of living species as a justification for the loss of air sacs despite a gain in body mass I argue to be unfounded given archaeological evidence, which suggests that the laryngeal air sacs may have been lost only after size reduction in Homo sapiens from Homo heidelbergensis.

Finally, I suggest two further justifications for loss of the laryngeal air sacs in homo sapiens. First, the linguistic niche of hunting in the environment in which early hominin hunters have been posited to exist – the savannah – would have been better suited to higher frequency, directional calls as opposed to lower frequency, multidirectional calls. The loss of air sacs would have then been directly advantageous, as lower frequencies produced by air sac vocalisations over bare ground have been shown to favour multidirectional over targeted utterances (Frey and Gebler, 2003). Secondly, the reuse of air stored in air sacs could have possibly been disadvantageous toward sustained, regular heavy breathing, as would occur in a similar hunting environment.

References:

Boer, B. de. (to appear). Air sacs and vocal fold vibration: Implications for evolution of speech.

Fitch, T. (2006). Production of Vocalizations in Mammals. Encyclopedia of Language and Linguistics. Elsevier.

Frey, R, & Gebler, A. (2003). The highly specialized vocal tract of the male Mongolian gazelle (Procapra gutturosa Pallas, 1777–Mammalia, Bovidae). Journal of anatomy, 203(5), 451-71. Retrieved June 1, 2011, from http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1571182&tool=pmcentrez&rendertype=abstract.

Frey, Roland, Gebler, Alban, Fritsch, G., Nygrén, K., & Weissengruber, G. E. (2007). Nordic rattle: the hoarse vocalization and the inflatable laryngeal air sac of reindeer (Rangifer tarandus). Journal of Anatomy, 210(2), 131-159. doi: 10.1111/j.1469-7580.2006.00684.x.

Martínez, I., Arsuaga, J. L., Quam, R., Carretero, J. M., Gracia, a, & Rodríguez, L. (2008). Human hyoid bones from the middle Pleistocene site of the Sima de los Huesos (Sierra de Atapuerca, Spain). Journal of human evolution, 54(1), 118-24. doi: 10.1016/j.jhevol.2007.07.006.

Hewitt, G., MacLarnon, A., & Jones, K. E. (2002). The functions of laryngeal air sacs in primates: a new hypothesis. Folia primatologica international journal of primatology, 73(2-3), 70-94. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/12207055.


Sound good? I hope so! That’s all for now.

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