Why evolutionary linguists shouldn’t study languages

How many languages do you speak?  This is actually a difficult question, because there’s no such thing as a language, as I argue in this video.

This is a video of a talk I gave as part of the Edinburgh University Linguistics & English Language Society’s Soap Vox lecture series.  I argue that ‘languages’ are not discrete, monolithic, static entities – they are fuzzy, emergent, complex, dynamic, context-sensitive categories.  I don’t think anyone would actually disagree with this, yet some models of language change and evolution still include representations of a ‘language’ where the learner must ‘pick’ a language to speak, rather than picking variants and allowing higher-level categories like languages to emerge.

In this lecture I argue that languages shouldn’t be modelled as discrete, unchanging things by demonstrating that there’s no consistent, valid way of measuring the number of languages that a person speaks.

The slides aren’t always in view (it improves as the lecture goes on), but I’ll try and write this up as a series of posts soon.

The origins of word order

A paper by Gell-Mann & Ruhlen in PNAS this week conducts a phylogenetic analysis of word order in languages and concludes that SOV is the most likely ancestor language word order.  The main conclusions from the analysis are:

(i) The word order in the ancestral language was SOV.

(ii) Except for cases of diffusion, the direction of syntactic change, when it occurs, has been for the most part SOV > SVO and, beyond that, SVO > VSO/VOS with a subsequent reversion to SVO occurring occasionally. Reversion to SOV occurs only through diffusion.

(iii) Diffusion, although important, is not the dominant process in the evolution of word order.

(iv) The two extremely rare word orders (OVS and OSV) derive directly from SOV.

This analysis agrees with Luke Maurtis‘ work on function and Uniform Information Density (blogged about here).

Cultural artefact from 25,000 years ago is transmitted horizontally

Jonnie Hughes writes this week about his time spent with the Sepik tribes of Papua New Guinea (tipped off by Michael Pleyer). As part of a documentary series, Hughes visited them and then arranged for some of the tribe elders to visit Britain. Of all the different technologies they encountered in Britain, the one that had the biggest impact was the idea of putting feathers on arrows to make them fly straight. The Sepik tribes used to achieve straight flight by using very heavy arrows, but a five minute tutorial at an archery range in a local community centre gave them the technology to use lighter arrows.  This meant that a hunter could carry more arrows and catch more prey.

Fletching technology is thought to date from as early as 25,000 years ago  (Ötzi the Iceman had some 5,000 years ago), so seems like an unlikely candidate for a horizontally transmitted cultural artefact.  Yet, with the world becoming more globalised, isolated communities are now exposed to not only modern technology, but the whole history of development that they can adopt.  Indeed, as Hughes relates, the Sepik tribes are now on Facebook and have access to Wikipedia articles on archery.

This is, of course, a nightmare for people trying to study the transmission of cultural artefacts.  What is the descent of fletching in the Sepik tribes?  Is it horizontal transmission from modern-day British archers?  Or, since the transmitter in question was re-creating traditional techniques, was it horizontal transmission from 15th century Britain (when archery was last widespread), or is it horizontal transmission from the original developers of fletching thousands of years ago?  If they continue to borrow technology from wikipedia articles, which are written by dozens of people from all over the world, what is the transmission trajectroy of these ideas?

Along with stories like the hunger-suppressing properties of Hoodia plant being transmitted from hunter-gatherers from the Kalahari to industrialised western cultures, the descent of technologies does not seem to respect cultural or historical boundaries.

Given the theme of this story, it’s strange that Hughes’ new book gives the impression of re-inventing the wheel.  The brilliantly titled “On the Origin of Tepees: The Evolution of Ideas (and Ourselves)” has the following introduction:

Throughout history, we humans have prided ourselves on our capacity to have ideas, but perhaps this pride is misplaced. Perhaps ideas have us. After all, ideas do appear to have a life of their own. And it is they, not us, that benefit most when they are spread. Many biologists have already come to the opinion that our genes are selfish entities, tricking us into helping them to reproduce. Is it the same with our ideas?

Jonnie Hughes, a science writer and documentary filmmaker, investigates the evolution of ideas in order to find out. Adopting the role of a cultural Charles Darwin, Hughes heads off, with his brother in tow, across the Midwest to observe firsthand the natural history of ideas—the patterns of their variation, inheritance, and selection in the cultural landscape. In place of Darwin’s oceanic islands, Hughes visits the “mind islands” of Native American tribes. Instead of finches, Hughes searches for signs of natural selection among the tepees.

An evolutionary approach to cultural transmission?  What a great idea.

I may be too harsh here, it actually looks like quite a fun and interesting book.  Perhaps there are already orders paced on Amazon by members of the Sepik tribes.

 

Hughes’ article: The tribesman who facebook friended me

Cultural differences in lateral transmission: Phylogenetic trees are OK for Linguistics but not biology

The three areas under analysis

An article in PLos ONE debunks the myth that hunter-gatherer societies borrow more words than agriculturalist societies. In doing so, it suggests that horizontal transmission is low enough for phylogenetic analyses to be a valid linguistic tool.

Lexicons from around 20% of the extant languages spoken by hunter-gatherer societies were coded for etymology (available in the supplementary material). The levels of borrowed words were compared with the languages of agriculturalist and urban societies taken from the World Loanword Database.  The study focussed on three locations:  Northern Australia, northwest Amazonia, and California and the Great Basin.

In opposition to some previous hypotheses, hunter-gatherer societies did not borrow significantly more words than agricultural societies in any of the regions studied.

The rates of borrowing were universally low, with most languages not borrowing more than 10% of their basic vocabulary.  The mean rate for hunter-gatherer societies was 6.38% while the mean for 5.15%.  This difference is actually significant overall, but not within particular regions.  Therefore, the authors claim, “individual area variation is more important than any general tendencies of HG or AG languages”.

Interestingly, in some regions, mobility, population size and population density were significant factors.  Mobile populations and low-density populations had significantly lower borrowing rates, while smaller populations borrowed proportionately more words.  This may be in line with the theory of linguistic carrying capacity as discussed by Wintz (see here and here).  The level of exogamy was a significant factor in Australia.

The study concludes that phylogenetic analyses are a valid form of linguistic analysis because the level of horizontal transmission is low.  That is, languages are tree-like enough for phylogenetic assumptions to be valid:

“While it is important to identify the occasional aberrant cases of high borrowing, our results support the idea that lexical evolution is largely tree-like, and justify the continued application of quantitative phylogenetic methods to examine linguistic evolution at the level of the lexicon. As is the case with biological evolution, it will be important to test the fit of trees produced by these methods to the data used to reconstruct them. However, one advantage linguists have over biologists is that they can use the methods we have described to identify borrowed lexical items and remove them from the dataset. For this reason, it has been proposed that, in cases of short to medium time depth (e.g., hundreds to several thousand years), linguistic data are superior to genetic data for reconstructing human prehistory “

Excellent – linguistics beats biology for a change!

However, while the level of horizontal transmission might not be a problem in this analysis, there may be a problem in the paths of borrowing.  If a language borrows relatively few words, but those words come from many different languages, and may have many paths through previous generations, there may be a subtle effect of horizontal transition that is being masked.  The authors acknowledge that they did not address the direction of transmission in a quantitative way.

A while ago, I did study of English etymology trying to quantify the level of horizontal transmission through time (description here).  The graph for English doesn’t look tree-like to me, perhaps the dynamics of borrowing works differently for languages with a high level of contact:

Claire Bowern, Patience Epps, Russell Gray, Jane Hill, Keith Hunley, Patrick McConvell, Jason Zentz (2011). Does Lateral Transmission Obscure Inheritance in Hunter-Gatherer Languages? PLoS ONE, 6 (9) : doi:10.1371/journal.pone.0025195

Stephen Fry’s Planet Word

Stephen Fry has embarked on a series of documentaries about language, beginning with the evolution of language which he calls ‘the final frontier’ of human understanding.  The typical documentary hype is all here:  Stephen Pinker sits in a gigantic fish tank with bits of taxidermied brain lying around like sandwiches; Michael Tomasello appears to live in a tropical primate enclose; Fry conducts his studies from a medieval study complete with quills, a CGI tree of languages and a talking parrot.

Despite this, it was actually a coherent and comprehensive review of topics in the field: Language versus communication in animals, phisological constraints of language, creativity and the desire to share information, the pragmatic origins of language, FoxP2 and the poverty of the stimulus. Bilingualism is even added to this cannon of interesting ways to approach the origins of language, somewhat tempered by Fry’s question “wouldn’t it be better if everybody spoke Esperanto?”.

Mercifully, Fry seems to be actually interested rather than trying to build up the conspiracy plot format endemic in other science documentaries.  There are some odd diversions to a Klingon version of Hamlet, a trip to a German Christmas market and a slightly awkward re-enactment of a feral child case, but all in all the message is not objectionable: There is a graded difference between non-human and human communication, it’s partly genetic and partly cultural and languages continually change under pressures to be learned and to express new ideas.  There are also welcome additions of the original Wug test and, of course, Fry & Laurie’s seminal sketch about language.

Overall, I’d say it was the second best documentary the BBC have made about the origins of language.

Here’s a clip:

 

Also a clip of Fry talking about the series:

The evolution of computer science: Connecting top-down and bottom-up

David Krakauer from the Santa Fe Institute asks “what is intelligence?” and discusses the rift in the field of computer science between the top down, symbolic approach to cognition (how can we make a machine play chess?)  and the bottom-up, inferential approach (how can we evolve a general-intelligence machine?).  He suggests that the singularity – when machines will outpace human beings – will occur only when machines master both aspects.  But is it a good idea to trust them?

This is a typical SFI talk, sweeping over evolving brain size, poetry, the Turing test, Evolution, the Matrix, Blade Runner and Doctor Strangelove. Fantastically, Krakauer mentions my work on a cultural singularity that I blogged about here!

Ultimately, his point is very similar to Adam Curtis’ documentary All Watched Over by Machines of Loving Grace, which is also brilliant.

See Krakauer’s talk here.

The USA: Most linguistically diverse country on the planet?

When asked to name a linguistically diverse place, I would have said Papua New Guinea, and if asked to name a stereotypically monolingual country, I would have named the USA.  However, this recent report from the New York Times suggests that, due to its large immigrant population, New York harbours more endangered languages than anywhere else on Earth (tipped off from Edinburgh University’s Lang Soc Blog).  From a field linguists’ point of view this may make discovery of and access to minority languages much easier (although may mean the end of exotic holidays).  From a cultural evolution point of view, a more global community may mean a radically different kind of competition between languages.  Nice video below:

Compositionality and Bilingualism

Last week I put up a link to an online experiment.  Here’s the results! You can still do the experiment first, if you like, here.  Source code and raw results at the bottom.

Languages evolve over time under a pressure to be learned by a new generation.  Does learning two languages at once effect this pressure? My experiment says … maybe.

These pressures include ones for learnability (compression) and expressivity (able to express a large variety of meanings, Kirby, Cornish & Smith, 2008).  Bilingualism seems like an unlikely ability since learning an extra language leaves the speaker potentially no more expressive at a cost of an increase in the amount of effort required to learn it.  There is no pressure for one language structure (e.g. English) to adapt to another language (e.g. Mandarin) so that they can become optimally learnable and expressive as a single medium.  That is, there’s no reason to assume that expressivity and learnability pressures apply across languages (which are not being used by the same people).

Nevertheless, children display an aptitude and a willingness to learn and use multiple languages simultaneously, and at a similar rate to monolingual children.  Therefore, languages do seem to have adapted to be learnable simultaneously.  Does the compatibility of languages point to a strong innate property of language?  In contrast, it might point to underlying similarity in the structure of languages, brought about by universal principles of communication.

Continue reading “Compositionality and Bilingualism”