Category: Science

Linguistic Structure: the Result of L2 Learners?

Wray and Grace (2007) propose that the structure of a language is dependent of the social structure of the population who speak it. Lupyan & Dale (2010) later showed this using statistical analysis. This has been discussed extensively on this blog before:

http://www.replicatedtypo.com/science/language-as-a-complex-adaptive-system/422/

http://www.replicatedtypo.com/uncategorized/memory-social-structure-and-language-why-siestas-affect-morphological-complexity/2382/

One of the proposed reasons for why large population size is thought to affect linguistic structure is that larger populations will have a larger ratio of second language (L2) speakers to first language (L1) speakers.

Languages within exoteric niches (large population and geographical spread with many language neighbors) have been shown to be more more morphologically isolating and, as a result, regular. This has proposed to be because of the biases of adult second language learners.

Esoteric languages are more irregular and morphologically complex and idiosyncratic. This is thought to be because of the biases of child learners.

There are studies which show that adult learners have a tendency to regularise languages but only under some circumstances. Hudson Kam & Newport (2009) show that adult learners will regularise unpredictable variability but only if it exists above a certain level of scatter and complexity.

As for the learning biases of children, Wray & Grace (2007) cite only one study which looked at children who were ‘native’ speakers of Esperanto (Bergen, 2001). Bergen (2001) found that the language that the children learnt displayed a loss of the accusative case and also displayed attrition in the tense system. Although Wray & Grace (2007) suggest that this explains patterns seen in esoteric communities, it may not be as straight forward as they suggest. The evidence suggests that esoteric conditions are going to display more morphological strategies in their languages which is the opposite to the biases the child learners of Esperanto are displaying. The children are rejecting morphological strategies in favour of attrition and word order.

I wanted to point out in this post that there is evidence to suggest that adult learners preserve irregularities and idiosyncrasies, while children learners regularize (suggesting the opposite to Wray & Grace).

Studies which have addressed these problems include Hudson Kam & Newport (2005) where adult learners of an artificial language preserved unpredictable variation and child learners of the same language regularized it. Hudson Kam & Newport (2009) show in a similar study that child learners of an artificial language will regularise unpredictable irregularity but, as mentioned above, adult learners will only do this where the irregularity passes a certain level of complexity.

However, some evidence does support Wray & Grace’s (2007) proposal about adult learners.  Smith & Wonnacott (2010) show that despite there being a tendency within individual adult learners to maintain the level of unpredicted variability within the language learning process, when put into a diffusion chain of adult learners the language regularises.  Smith & Wonnacott (2010) suggest that gradual processes such as this can explain the regularisation of languages over time. While this fits nicely with Wray & Grace’s (2007) theory there is still the problem that children are just as liable to regularise as adults if not more so.

 

This is just some relevant experiments which I thought lent something to the debate. I know there are other factors which have been proposed to have an effect on linguistic structure. I was just curious about people’s opinions on quite to what level L2 speakers have an effect.

Recall dependent on language?

A new study has been published in Current Biology which offers evidence to suggest that monkeys have the capacity for both recognition and recall of simple shapes.

The study showed that rhesus monkeys can recall shapes from memory. This was shown using an experiment which had the monkeys reproduce shapes on a computer touch screen. These findings suggest that the memory of humans and old world monkeys may be more similar than we previously suspected.

Recall is separate and special in comparison to recognition as it shows an ability to remember and visualise things which are not present in the moment. This is an ability which is implicated in skills such as planning and imagining. This is also thought to enhance things like navigation and social behavior. In the past it has thought that an ability to recall none present items is dependent on language. This has been suggested in the past by prominent linguists such as Charles Hockett who thought that the ability of displacement was facilitated by language and was a driving force behind its evolution.

Because of a lack of demand for recall in the lives of monkeys they will not use their recollection skills very often in the wild. In the press release, Benjamin Basile, who lead the study said:

“Maybe it’s often just easier to recognize the monkey, the food, or the landmark in front of you. What we do know is that they do seem to have the ability to recall information in the lab.”

Experiments with humans have shown that recall and recognition require different types of memory. This has been difficult to show with other primates as recall tests are difficult to devise for monkeys because they can’t draw or talk.

The experiment used five rhesus monkeys who were trained on a recall test in which they had to reproduce a simple figure on a touch screen from memory. The shapes were made up of large pixels or boxes on a screen. The monkeys were shown these shapes and then, after a delay, were presented with part of the shape in a different location. The monkeys had to replicate the rest of the shape by touching where the other pixels should be.

The monkeys remembered less in recall than in recognition tests which is the same case in humans. However, the recall performance deteriorated more slowly over time. The monkeys were also able to transfer their ability to recall shapes to novel shapes as they were shown to be able to recall shapes which weren’t used in training.

This ability has probably been present since our last common ancestor with old world monkeys some 30 million years ago and is probably not facilitated by language.

The study hypothesises that:

“Recollection and familiarity likely evolved because they solved functionally incompatible problems. For example, familiarity does not support detailed memory for context, but it is quick and resistant to distraction. Recollection is slower and more vulnerable to distraction but supports a more detailed and flexible use of memory. Familiarity might better allow rapid responses to foods and predators under distracting conditions, whereas recollection might be necessary to access knowledge of distant food locations or past social interactions for planning future behavior.”

References

Benjamin M. Basile, Robert R. Hampton. Monkeys Recall and Reproduce Simple Shapes from Memory. Current Biology, 28 April 2011

 

Bonobos Extract Meaning from Call Sequences

A new study appeared yesterday on PlosOne by Clay and Zuberbühler of St Andrews University on the communicative ability of bonobos.

Studies have been done in the past on language-trained bonobos such as Kanzi which have revealed some remarkable abilities that the species has with regards to representational and communication tasks.

These studies have focussed on trained apes which are reared in unnatural environments and extensively trained on artificial languages. This has produced some interesting results though research into bonobos’ natural communication has been thin on the ground until now.

Clay and Zuberbühler address this gap in the research with a playback study on the natural vocal communication of bonobos.

Bonobos are known to produce five distinct vocal signals when finding food, these have been demonstrated to be combined together to make longer call sequences. The study found that individual call types were poor indicators of food quality but that calls which displayed a concatenation of signals were much better indicators.

The study looked into whether receivers could extract meaning about the quality of food encountered by the caller by integrating across different call sequences.

They started by training four captive bonobos to find two types of foods in two different locations, those which are more preferred such as kiwis and those which are less preferred such as apples. The apes were recorded when finding these different food types and these recordings were used in the playback experiments. When the bonobos discovered their preferred food they emitted higher pitched long barks and short “peeps” and when they discovered the less-preferred food they made lower pitch “peep-yelps” and yelps. Sequences of the four calls which used different compositions were played back to bonobos who were familiar with those apes who had originally made the calls. All sequences contained the same number of calls. In response to these playbacks the study found that the apes devoted significantly more effort and time searching the space which was known to contain the food type indicated by the call sequence (shown in the graph below).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The bonobos were shown to attend not just to individual calls but to the entire sequences before they made inferences about the food encountered by a caller.

These results provide the first empirical evidence that bonobos are able to extract information about external events by attending to natural vocal sequences made by other bonobos. This study really highlights the importance of call combinations in their natural communication system.

References
Clay Z, Zuberbühler K, 2011 Bonobos Extract Meaning from Call Sequences. PLoS ONE 6(4): e18786. doi:10.1371/journal.pone.0018786

Neanderthal-human Hybrids

Paul Mason and Robert Short have an article out called Neanderthal-human hybrids (I wonder what that’s about?). Here is the abstract:

Evidence from studies of nuclear and mitochondrial DNA extracted from Neanderthal fossils and humans points to fascinating hypotheses concerning the types of interbreeding that occurred between these two species. Humans and Neanderthals share a small percentage of nuclear DNA. However, humans and Neanderthals do not possess the same mito­chondrial DNA. In mammals, mitochondrial DNA is exclusively maternally inherited. Taking into account an understanding of interspecific hybridity, the available data leads to the hypothesis that only male Neanderthals were able to mate with female humans. If Haldane’s Law applied to the progeny of Neanderthals and humans, then female hybrids would survive, but male hybrids would be absent, rare, or sterile. Interbreeding between male Neanderthals and female humans, as the only possible scenario, accounts for the presence of Neanderthal nuclear DNA, the scarcity of Neanderthal Y-linked genes, and the lack of mitochondrial DNA in modern human populations.

Paul Mason previously wrote about the topic over at Neuroanthroplogy, so I really don’t have much more to say on the topic, other than that I’ll get around to reading it over the next couple of days. I’m curious to see if the usual suspects in the genetics (Razib Khan), anthropological (Dienekes) and evolutionary (John Hawks) communities offer some food for thought on the topic.

For me, I’m actually more interested in Mason’s recent work on degeneracy… But that’s for a later post 😉

Replicated Hauser Results

Some of you may remember last summer Marc Hauser was found guilty of research misconduct. This investigation raised questions about several publications including a paper from 2007 in Science. This paper looked into the ability of non-human primates to understand the intentions of a human experimenter by interpreting his gestures.

Today Science has published a partial replication of the study in question which confirms the original findings that chimpanzees, cotton-top tamarins, and rhesus macaques can distinguish intentional gestures, such as pointing to indicate a container with food inside, from “accidental” actions such as a hand flopping against a container.

The Science wesite states the following:

Following the Harvard misconduct investigation, first author Justin Wood, now an assistant professor at the University of Southern California in Los Angeles, wrote to Science in June 2010 to notify the journal that the investigation had revealed that the original field notes for the rhesus experiments could not be found:

“An internal examination at Harvard University determined that there are no field notes, records of aborted trials, or subject identifying information associated with the rhesus monkey experiments; however, the research notes and videotapes for the tamarin and chimpanzee experiments were accounted for. Professor Hauser states that “most of the rhesus monkey observations were hand written by [co-author David D.] Glynn on a piece of paper, and then the daily results tallied and reported to Wood over email or by phone” and then the raw data were discarded. The research assistant who performed the experiments (Glynn) confirmed that these field notes were discarded.”

Hauser and Wood returned to Cayo Santiago island in Puerto Rico to redo the experiments from the 2007 paper with the same population of free-ranging rhesus monkeys. Their findings, including field notes and video trials, are available online and they essentially match those reported in the original paper.

It is still not known what went wrong with the original experiment, a statement issued by Science today only says the following:

We stress that this new publication aims only to determine whether the original rhesus monkey experiments from the 2007 paper can be replicated. It has no bearing on questions raised about Dr. Hauser’s larger body of work.

This article from Science Inside quotes Dario Maestriperi as saying:

“The results of this replication are straightforward and entirely consistent with those of the original study. If the authors’ interpretation of their results is correct, these findings are very important and represent one of the clearest demonstrations that nonhuman primates can interpret the behavior of other individuals as intentional or non-intentional….Since the experimenter who tested the rhesus monkeys in the replication study appeared from the video to be the first author on the paper, Justin Wood, he was clearly knowledgeable of the hypotheses being tested and had some strong expectations and desires about the monkeys’ performance on the test.”

So is this replication a clarification of groundbreaking findings or could the monkey’s behaviour be down to the Clever Hans effect?

Meanwhile investigations into Hauser’s research are still ongoing and he is still banned from teaching for the next academic year.

 

The Return of the Phoneme Inventories

Right, I already referred to Atkinson’s paper in a previous post, and much of the work he’s presented is essentially part of a potential PhD project I’m hoping to do. Much of this stems back to last summer, where I mentioned how the phoneme inventory size correlates with certain demographic features, such as population size and population density. Using the the UPSID data I generated a generalised additive model to demonstrate how area and population size interact in determining the phoneme inventory size:

Interestingly, Atkinson seems to derive much of his thinking, at least in his choice of demographic variables, from work into the transmission of cultural artefacts (see here and here). For me, there are clear uses for these demographic models in testing hypotheses for linguistic transmission and change, as I see language as a cultural product. It appears Atkinson reached the same conclusion. Where we depart, however, is in our overall explanations of the data. My major problem with the claim is theoretical: he hasn’t ruled out other historical-evolutionary explanations for these patterns.

Before we get into the bulk of my criticism, I’ll provide a very brief overview of the paper.

Continue reading “The Return of the Phoneme Inventories”

Cultural Transmission observed in Whales

A new paper in Current Biology, published today has revealed that the songs of Humpbacked Whales are passed through the ocean by mechanisms of cultural transmission.

Cultural transmission is defined as the social learning of information or behaviours either over generations or via peers. It has been seen to occur in primates, cetaceans and birds.

Cultural transmission over generations, i.e. parent passing socially learnt traits to their offspring, is known as vertical transmission and cultural transmission via peers, unrelated individuals from within generations, is known as horizontal transmission. In humans, languages and memes are transmitted, learned and (in a lot of cases) evolved in this manner.

Male humpback whales have a repetitive and evolving ‘song’ which acts as a vocal sexual display. This song is highly repetitive and is used, by mechanisms of social sorting and attraction, to allow for sexual selection within the whale population. All males within a population are known to conform to the current version of the display (song type), and similarities have been seen to exist among the songs of populations within an ocean basin.

The study being discussed presents very strong evidence for patterns of horizontal transmission, whereby song types spread unidirectionally and rapidly in the pacific ocean eastward through populations in the western and central South Pacific. The study was done over an 11-year period. This is the first documentation of a repeated, dynamic cultural evolution occurring across multiple populations at such a large geographic scale and across such a large time scale.

The patterns of cultural transmission seen in these whales songs are analogous to the same mechanisms we see in humans given that the songs are subject to mistakes and changes which are replicated. This causes the same mechanisms we see in the cultural transmission of language. The authors note that the level and rate of change seen in the whales is unparalleled in any other nonhuman animal and involves culturally driven change at a vast scale.

They also state that:

Investigating the underlying mechanisms of song evolution may yield powerful insights into the transmission of cultural traits and the evolution of culture and plasticity in sexually selected traits.

They also observed that at least one of the song types was transmitted between two different ocean basins, the Indian and South Pacific Ocean. It’s amazing to think how far a single song type can be horizontally transmitted.

Humpback whale song is unique among the animal kingdom due to the conformity to the current norm. This is coupled with high plasticity in the trait (ability to change their song based on whatever the new ‘norm’ is). Why both plasticity and conformity might be selected, how these interact with sexual selection, and how cultural evolution influences both are intriguing questions in need of consideration.

References

Garland, E. C.; Goldizen, A. W.; Rekdahl, M. L.; Constantine, R.; Garrigue, C.; Hauser, N.; Poole, M. M.; Robbins, J.; Noad, M. J. (2011) Dynamic Horizontal Cultural Transmission of Humpback Whale Song at the Ocean Basin Scale. Current biology : CB doi:10.1016/j.cub.2011.03.019

Phonemic Diversity Supports a Serial Founder Effect Model of Language Expansion from Africa

Just read about an article on phoneme diversity via GNXP and Babel’s Dawn. Hopefully I’ll share some of my thoughts on the paper this weekend as it clearly ties in with work I’m currently doing (see here and here). Below is the abstract:

Human genetic and phenotypic diversity declines with distance from Africa, as predicted by a serial founder effect in which successive population bottlenecks during range expansion progressively reduce diversity, underpinning support for an African origin of modern humans. Recent work suggests that a similar founder effect may operate on human culture and language. here I show that the number of phonemes used in a global sample of 504 languages is also clinal and fits a serial founder-effect model of expansion from an inferred origin in Africa. This result, which is no explained by more recent demographic history, local language diversity, or statistical non-independence within language families, points to parallel mechanisms shaping genetic and linguistic diversity and supports an African origin of modern human languages.

Reference: Atkinson, Q.D (2011). Phonemic Diversity Supports a Serial Founder Effect Model of Language Expansion from Africa. Science 332, 346. DOI: 10.1126/science.1199295.

Update: I’ve given a lengthier response here.

The Parental Antagonism Theory of Language Evolution

Human Biology are publishing a special issue on “Integrating genetic and Cultural Evolutionary Approaches to Language” this month! Abstracts for all of the papers can be found here.

William Brown‘s paper has been published on his blog ahead of the boat today. The Abstract is below and there is a link to the paper at the bottom.

Language—as with most communication systems—likely evolved by means of natural selection. Accounts for the natural selection of language can usually be divided into two scenarios, either of which used in isolation of the other are insufficient to explain the phenomena: (1) there are group benefits from communicating, and (2) there are individual benefits from being a better communicator. In contrast, this paper argues that language emerged during a coevolutionary struggle between parental genomes via genomic imprinting, which is differential gene expression depending on parental origin of the genetic element. It is hypothesized that relatedness asymmetries differentially selected for patrigene-caused language phenotypes (e.g., signals of need) to extract resources from mother early in child development and matrigene-caused language phenotypes (e.g.,  socially transmitted norms) to influence degree of cooperativeness  among kin later in development. Unlike previous theories for language evolution, parental antagonism theory generates testable predictions at the proximate (e.g., neurocognitive areas important for social transmission and language capacities), ontogenetic (e.g., the function of language at different points of development), ultimate (e.g., inclusive fitness), and phylogenetic levels (e.g., the spread of maternally derived brain components in mammals, particularly in the hominin lineage), thus making human capacities for culture more tractable than previously thought.

Brown, W.M. (2011). The parental antagonism theory of language evolution: Preliminary evidence for the proposal. Human Biology, 83 (2)

Evolved structure of language shows lineage-specific trends in word-order universals

Via Simon Greenhill:

Dunn M, Greenhill SJ, Levinson SC, & Gray RD (2011). Evolved structure of language shows lineage-specific trends in word-order universals. Nature.

Some colleagues and I have a new paper out in Nature showing that the evolved structure of language shows lineage-specific trends in word-order universals. I’ve written an overview/FAQ on this paper here, and there’s a nice review of it here and here.

The Abstract:

Languages vary widely but not without limit. The central goal of linguistics is to describe the diversity of human languages and explain the constraints on that diversity. Generative linguists following Chomsky have claimed that linguistic diversity must be constrained by innate parameters that are set as a child learns a language. In contrast, other linguists following Greenberg have claimed that there are statistical tendencies for co-occurrence of traits reflecting universal systems biases, rather than absolute constraints or parametric variation. Here we use computational phylogenetic methods to address the nature of constraints on linguistic diversity in an evolutionary framework. First, contrary to the generative account of parameter setting, we show that the evolution of only a few word-order features of languages are strongly correlated. Second, contrary to the Greenbergian generalizations, we show that most observed functional dependencies between traits are lineage-specific rather than universal tendencies. These findings support the view that—at least with respect to word order—cultural evolution is the primary factor that determines linguistic structure, with the current state of a linguistic system shaping and constraining future states.