Tag Archives: complexity

Tool making and Language Evolution

There’s an often cited gap in tool making history in which humans did not advance from simple Oldowan tools (which date back to about 2.5 million years ago) until about 500,000 years ago when progress became much faster. There is much debate as to whether this gap in progress is the result of the cognitive abilities to make more innovative tools or if it was an issue of dexterity.

A recent article by Faisal et al. (2010) “The Manipulative Complexity of Lower Paleolithic Stone Toolmaking” has tried to address these problems by assessing the manipulative complexity of tool making tasks from the Oldowan tools to the more advanced hand axes from much later.

A stone ‘core’ (A) is struck with a hammerstone (B) in order to detach sharp stone ‘flakes’. In Oldowan toolmaking (C, top) the detached flakes (left in photo) are used as simple cutting tools and the core (right in photo) is waste. In Acheulean toolmaking (C, bottom), strategic flake detachments are used to shape the core into a desired form, such as a handaxe. Both forms of toolmaking are associated with activation of left ventral premotor cortex (PMv), Acheulean toolmaking activates additional regions in the right hemisphere, including the supramarginal gyrus (SMG) of the inferior parietal lobule, right PMv, and the right hemisphere homolog of anterior Broca's area: Brodmann area 45 (BA 45).

The following is taken from a press release from Eureka.org:

Researchers used computer modelling and tiny sensors embedded in gloves to assess the complex hand skills that early humans needed in order to make two types of tools during the Lower Palaeolithic period, which began around 2.5 million years ago. The cross-disciplinary team, involving researchers from Imperial College London, employed a craftsperson called a flintnapper to faithfully replicate ancient tool-making techniques.

The team say that comparing the manufacturing techniques used for both Stone Age tools provides evidence of how the human brain and human behaviour evolved during the Lower Palaeolithic period.

The flintnapper who participated in today’s study created two types tools including the razor-sharp flakes and hand-held axes. He wore a data glove with sensors enmeshed into its fabric to record hand and arm movements during the production of these tools.

After analysing this data, the researchers discovered that both flake and hand-held axe manufacturing techniques were equally complex, requiring the same kind of hand and arm dexterity. This enabled the scientists to rule out motor skills as the principal factor for holding up stone tool development.

The team deduced from their results that the axe-tool required a high level of brain processing.

This has implications for language evolution as brain scans from tool makers have shown significant overlap with areas involved in discourse-level language processing as well as complex hand gestures. The study finishes with the following:

…the anatomical overlap of Late Acheulean toolmaking and right hemisphere linguistic processing may reflect the flexible “mapping” of diverse overt behaviors onto shared functional substrates in the brain. This implies that: 1) selection acting on either language or toolmaking abilities could have indirectly favored elaboration of neural substrates important for the other, and 2) archaeological evidence of Paleolithic toolmaking can provide evidence for the presence of cognitive capacities also important to the modern human faculty for language.

Read the original article at PLoS ONE:

http://www.plosone.org/article/info:doi/10.1371/journal.pone.0013718

Domain-General Regions and Domain-Specific Networks

The notion of a domain-specific, language acquisition device is something that still divides linguists. Yet, in an ongoing debate spanning at least several decades, there is still no evidence, at least to my knowledge, for the existence of a Universal Grammar. Although, you’d be forgiven for thinking that the problem was solved many years ago, especially if you were to believe the now  sixteen-year old words of Massimo Piattelli-Palmarini (1994):

The extreme specificity of the language system, indeed, is a fact, not just a working hypothesis, even less a heuristically convenient postulation. Doubting that there are language-specific, innate computational capacities today is a bit like being still dubious about the very existence of molecules, in spite of the awesome progress of molecular biology.

Suffice to say, the analogy between applying scepticism of molecules and scepticism of Universal Grammar is a dud, even if it does turn out that the latter does exist. Why? Well, as stated above: we still don’t know if humans have, or for that matter, even require, an innate ability to process certain grammatical principles. The rationale for thinking that we have some innate capacity for acquiring language can be delineated into a twofold argument: first, children seem adept at rapidly learning a language, even though they aren’t exposed to all of the data; and second, cognitive science told us that our brains are massively modular, or at the very least, should entail some aspect that is domain specific to language (see FLB/FLN distinction in Hauser, Chomsky & Fitch, 2002). I think the first point has been done to death on this blog: cultural evolution can provide an alternative explanation as to how children successfully learn language (see here and here and Smith & Kirby, 2008). What I haven’t really spoken about is the mechanism behind our ability to process language, or to put it differently: how are our brains organised to process language?

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Mapping Linguistic Phylogeny to Politics

Note: Most of the content in this post is refuted wonderfully in the comment section by one of the original authors of the paper. I highly recommend reading the comments, if you’re going to read this at all – that’s where the real meat lies. I’m keeping this post up, finally, because it’s good to make mistakes and learn from them. -Richard

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I had posted this already on the Edinburgh Language Society blog. I’ve edited it a bit for this blog. I should also state that this is my inaugural post on Replicated Typo; thanks to Wintz’ invitation, I’ll be posting here every now and again. It’s good to be here. Thanks for reading – and thanks for pointing out errors, problems, corrections, and commenting, if you do. Research blogging is relatively new to me, and I relish this unexpected chance to hone my skills and learn from my mistakes. (Who am I, anyway?) But without further ado:

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In a recent article covered in NatureNews in Societes Evolve in StepsTom Currie of UCL, and others, like Russell Gray of Auckland, use quantitative analysis of the Polynesian language group to plot socioanthropological movement and power hierarchies in Polynesia. This is based off of previous work, available here, which I saw presented at the Language as an Evolutionary Systemconference last July. The article claims that the means of change for political complexity can be determined using linguistic evidence in Polynesia, along with various migration theories and archaeological evidence.

I have my doubts. The talk that was given by Russell Gray suggested that there were still various theories about the migratory patterns of the Polynesians – in particular, where they started from. What his work did was to use massive supercomputers to narrow down all of the possibilities, by using lexicons and charting their similarities. The most probable were then recorded, and their statistical probability indicated what was probably the course of action. This, however, is where the ability for guessing ends. Remember, this is massive quantificational statistics. If one has a 70% probability chance of one language being the root of another, that isn’t to say that that language is the root, much less that the organisation of one determines the organisation of another. But statistics are normally unassailable – I only bring up this disclaimer because there isn’t always clear mapping between language usage and migration.

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Regularities in Cultural Evolution

I recently came across a post over at GNXP on the rise and crash of civilizations. It’s a really interesting discussion on a new paper by Currie et al. (2010), Rise and fall of political complexity in island South-East Asia and the Pacific. Here is the abstract:

There is disagreement about whether human political evolution has proceeded through a sequence of incremental increases in complexity, or whether larger, non-sequential increases have occurred. The extent to which societies have  decreased  in  complexity is  also unclear. These  debates have  continued  largely  in the absence  of rigorous, quantitative tests. We evaluated six competing models of political evolution in Austronesian-speaking societies using phylogenetic methods. Here we show that in the best-fitting model political complexity rises and falls in a sequence of small steps. This is closely followed by another model in which increases are sequential but decreases can be either sequential or in bigger drops. The results indicate that large, non-sequential jumps in political complexity have not occurred during the evolutionary history of these societies. This suggests that, despite the numerous contingent pathways of human history, there are regularities in cultural evolution that can be detected using computational phylogenetic methods. [My emphasis].

I don’t have much to add on the subject as I think Razib covered most of the relevant points, plus I haven’t even finished reading the paper yet (I’m hoping to get back into research blogging later this week). I will, however, post one of their figures that shows the dynamic between the rise and fall of political complexity, and how it shows regularity (btw, RJMCMC means Bayesian reversible-jump Markov chain Monte Carlo… if that helps you in any way):

Musings of a Palaeolinguist

Hannah recently directed me towards a new language evolution blog: Musings of a Palaeolinguist. From my reading of the blog, the general flavour seems to be focused on gradualist and abruptist accounts of language evolution. Here is a section from one of her posts, Evolution of Language and the evolution of syntax: Same debate, same solution?, which also touches on the protolanguage concept:

In my thesis, I went through a literature review of gradual and abruptist arguments for language evolution, and posited an intermediate stage of syntactic complexity where a language might have only one level of embedding in its grammar.  It’s a shaky and underdeveloped example of an intermediate stage of language, and requires a lot of exploration; but my reason for positing it in the first place is that I think we need to think of the evolution of syntax the way many researchers are seeing the evolution of language as a whole, not as a monolithic thing that evolved in one fell swoop as a consequence of a genetic mutation, but as a series of steps in increasing complexity.

Derek Bickerton, one of my favourite authors of evolutionary linguistics material, has written a number of excellent books and papers on the subject.  But he also argues that language likely experienced a jump from a syntax-less protolanguage to a fully modern version of complex syntax seen in languages today.  To me that seems unintuitive.  Children learn syntax in steps, and non-human species seem to only be able to grasp simple syntax.  Does this not suggest that it’s possible to have a stable stage of intermediate syntax?

I’ve generally avoided writing about these early stages of language, largely because I had little useful to say on the topic, but I’ve now got some semi-developed thoughts that I’ll share in another post. In regards to the above quote, I do agree with the author’s assertion of there being an intermediate stage, rather than Bickerton’s proposed jump. In fact, we see languages today (polysynthetic) where there are limitations on the level of embedding, with one example being Bininj Gun-wok. We can also stretch the discussion to look at recursion in languages, as Evans and Levinson (2009) demonstrate:

In discussions of the infinitude of language, it is normally assumed that once the possibility of embedding to one level has been demonstrated, iterated recursion can then go on to generate an infinite number of levels, subject only to memory limitations. And it was arguments from the need to generate an indefinite number of embeddings that were crucial in demonstrating the inadequacy of finite state grammars. But, as Kayardild shows, the step from one-level recursion to unbounded recursion cannot be assumed, and once recursion is quarantined to one level of nesting it is always possible to use a more limited type of grammar, such as finite state grammar, to generate it.

Some Links #19: The Reality of a Universal Language Faculty?

I noticed it’s almost been a month since I last posted some links. What this means is that many of the links I planned on posting are terribly out of date and these last few days I haven’t really had the time to keep abreast of the latest developments in the blogosphere (new course + presentation at Edinburgh + current cold = a lethargic Wintz). I’m hoping next week will be a bit nicer to me.

The reality of a universal language faculty? Melodye offers up a thorough post on the whole Universal Grammar hypothesis, mostly drawing from the BBS issue dedicated Evans & Levinson (2009)’s paper on the myth of language universals, and why it is a weak position to take. Key paragraph:

When we get to language, then, it need not be surprising that many human languages have evolved similar means of efficiently communicating information. From an evolutionary perspective, this would simply suggest that various languages have, over time, ‘converged’ on many of the same solutions.  This is made even more plausible by the fact that every competent human speaker, regardless of language spoken, shares roughly the same physical and cognitive machinery, which dictates a shared set of drives, instincts, and sensory faculties, and a certain range of temperaments, response-patterns, learning facilities and so on.  In large part, we also share fairly similar environments — indeed, the languages that linguists have found hardest to document are typically those of societies at the farthest remove from our own (take the Piraha as a case in point).

My own position on the matter is fairly straightforward enough: I don’t think the UG perspective is useful. One attempt by Pinker and Bloom (1990) argued that this language module, in all its apparent complexity, could not have arisen by any other means than via natural selection – as did the eye and many other complex biological systems. Whilst I agree with the sentiment that natural selection, and more broadly, evolution, is a vital tool in discerning the origins of language, I think Pinker & Bloom initially overlooked the significance of cultural evolutionary and developmental processes. If anything, I think the debate surrounding UG has held back the field in some instances, even if some of the more intellectually vibrant research emerged as a product of arguing against its existence. This is not to say I don’t think our capacity for language has been honed via natural selection. It was probably a very powerful pressure in shaping the evolutionary trajectory of our cognitive capacities. What you won’t find, however, is a strongly constrained language acquisition device dedicated to the processing of arbitrary, domain-specific linguistic properties, such as X-bar theory and case marking.

Babel’s Dawn Turns Four. In the two and half years I’ve been reading Babel’s Dawn it has served as a port for informative articles, some fascinating ideas and, lest we forget, some great writing on the evolution of language. Edmund Blair Bolles highlights the blog’s fourth anniversary by referring to another, very important, birthday:

This blog’s fourth anniversary has rolled around. More notably, the 20th anniversary of Steven Pinker and Paul Bloom‘s famous paper, “Natural Language and Natural Selection,” seems to be upon us. Like it or quarrel with it, Pinker-Bloom broke the dam that had barricaded serious inquiry since 1866 when the Paris Linguistic Society banned all papers on language’s beginnings. The Journal of Evolutionary Psychology is marking the Pinker-Bloom anniversary by devoting its December issue to the evolution of language. The introductory editorial, by Thomas Scott-Phillips, summarizes language origins in terms of interest to the evolutionary psychologist, making the editorial a handy guide to the differences between evolutionary psychology and evolutionary linguistics.

Hopefully I’ll have a post on Pinker and Bloom’s original paper, and how the field has developed over these last twenty years, at some point in the next couple of weeks. I think it’s historical importance will, to echo Bolles, be its value in opening up the field: with the questions of language origins and evolution turning into something worthy of serious intellectual investigation.

Other Links

Hypnosis reaches the parts brain scans and neurosurgery cannot.

Are Humans Still Evolving? (Part Two is here).

The Limits of Science.

On Language — Learning Language in Chunks.

Farmers, foragers, and us.

Tweet This.

On Music and The Brain.

Why I spoofed science journalism, and how to fix in.

The adaptive space of complexity.

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.

The Problem With a Purely Adaptationist Theory of Language Evolution

According to the evolutionary psychologist Geoffrey Miller and his colleagues (e.g Miller 2000b), uniquely human cognitive behaviours such as musical and artistic ability and creativity, should be considered both deviant and special. This is because traditionally, evolutionary biologists have struggled to fathom exactly how such seemingly superfluous cerebral assets would have aided our survival. By the same token, they have observed that our linguistic powers are more advanced than seems necessary to merely get things done, our command of an expansive vocabulary and elaborate syntax allows us to express an almost limitless range of concepts and ideas above and beyond the immediate physical world. The question is: why bother to evolve something so complicated, if it wasn’t really all that useful?

Miller’s solution is that our most intriguing abilities, including language, have been shaped predominantly by sexual selection rather than natural selection, in the same way that large cumbersome ornaments, bright plumages and complex song have evolved in other animals. As one might expect then, Miller’s theory of language evolution has been hailed as a key alternative to the dominant view that language evolved because it conferred a distinct survival advantage to its users through improved communication (e.g. Pinker 2003). He believes that language evolved in response to strong sexual selection pressure for interesting and entertaining conversation because linguistic ability functioned as an honest indicator of general intelligence and underlying genetic quality; those who could demonstrate verbal competence enjoyed a high level of reproductive success and the subsequent perpetuation of their genes. Continue reading

Population size predicts technological complexity in Oceania

ResearchBlogging.orgHere is a far-reaching and crucially relevant question for those of us seeking to understand the evolution of culture: Is there any relationship between population size and tool kit diversity or complexity? This question is important because, if met with an affirmative answer, then the emergence of modern human culture may be explained by changes in population size,  rather than a species-wide cognitive explosion. Some attempts at an answer have led to models which make certain predictions about what we expect to see when populations vary. For instance, Shennan (2001) argues that in smaller populations, the number of people adopting a particular cultural variant is more likely to be affected by sampling variation. So in larger populations, learners potentially have access to a greater number of experts, which means adaptive variants are less likely to be lost by chance (Henrich, 2004).

Models aside, and existing empirical evidence is limited with the results being mixed. I previously mentioned the gradual loss of complexity in Tasmanian tool kits after the population was isolated from mainland Australia. Elsewhere, Golden (2006) highlighted the case of isolated Polar Inuit, who lost kayaks, the bow and arrow and other technologies when their knowledgeable experts were wiped out during a plague.Yet two systematic studies (Collard et al., 2005; Read, 2008) of the Inuit case found no evidence for population size being a predictor of technological complexity.

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