Cultural Evolution: Brought to you by Bacardi

Didn’t I say that alcohol affects language evolution?

 

 

The video is actually a pretty good summary of many of the main issues surrounding cultural evolution and self domestication. Surprisingly, Bacardi have actually done some research on this:

I cannot wait to make a Bacardi-WALS data cocktail.

Bayesian phylogenetic analysis of Japonic languages

Lee & Hasegawa (2011) use phylogenetic methods to trace the origins of Japonic languages and dialects.  Two hypotheses are considered:  First, the farming/language dispersal hypothesis posits that the main factor for the divergence of genetic and linguistic diversity was agricultural expansion.  Second, the diffusion/transformation hypothesis posits that cultural innovations such as farming can diffuse between societies, and so genetic and linguistic diversity should not be linked.  The estimate of the common linguistic ancestor was in accordance with the farming/language dispersal hypothesis, again suggesting that that linguistic diversity followed genetic diversity.

The study is notable in considering dialects as well as languages and using etymology dictionaries to reconstruct forms from Middle and Old Japanese.  The analysis is also done with their own reconstructions and another, unrelated set.  The technique is similar to that used by Russel Gray et al. (2009) to study Pacific settlement patterns.

Lee S, & Hasegawa T (2011). Bayesian phylogenetic analysis supports an agricultural origin of Japonic languages. Proceedings. Biological sciences / The Royal Society PMID: 21543358

Gray, R., Drummond, A., & Greenhill, S. (2009). Language Phylogenies Reveal Expansion Pulses and Pauses in Pacific Settlement Science, 323 (5913), 479-483 DOI: 10.1126/science.1166858

Origins of Culture

NPR hosts a fascinating debate on the connections between science and art and the origins of culture.  The guests include the utterly bizarre mix of novelist Cormac McCarthy (The Road, No Country for old Men), filmmaker Werner Herzog (The cave of forgotten dreams, Grizzly Man),  and physicist Lawrence Krauss (The physics of Star Trek).  Artificial Intelligence, Neanderthal culture and our place in the universe.  And a buffalo humping a woman.

How old am I?

It’s my birthday!  But how old am I?  Well, that’s not such a straightforward question.  Even a seemingly well-defined concept such as age can be affected by cultural factors

First, my age in years is a bit of an estimate of the actual amount of time I’ve been alive, due to leap-years etc.  Second, a year is a culturally determined (although not all that arbitrary) amount of time.  But these are petty squabbles.

There are bigger differences.  For instance, there are cultural differences when it comes to the recall of birth dates.  And I’m not talking about saying you’re 24 when you’re 68.  Matched comparisons of age reporting in death certificates and census data found minimal differences for white Americans (Hill et al., 2000) but nearly half were inconsistent for African-Americans (Hill et al., 1997). These may be due to economic differences.

Furthermore, the definition of age can vary cross-culturally.  Knodel & Chyovan (1991) surveyed women between the ages of 15 and 49 in Thailand.  As well as finding that up to 20% reported an age that was more than one year different to their actual age, they surmised that most calculated their age as difference between the present year and the year of their birth, disregarding whether their birthday had passed.

 

So in some parts of the world I’ve been 26 for four months now, or was it 25?

 

Hill, M., Preston, S., Elo, I., & Rosenwaike, I. (1997). Age-Linked Institutions and Age Reporting among Older African Americans Social Forces, 75 (3) DOI: 10.2307/2580528

Hill, M., Preston, S., & Rosenwaike, I. (2000). Age Reporting among White Americans Aged 85+: Results of a Record Linkage Study Demography, 37 (2) DOI: 10.2307/2648119

Knodel J, & Chayovan N (1991). Age and birth date reporting in Thailand. Asian and Pacific population forum / East-West Population Institute, East-West Center, 5 (2-3) PMID: 12343437

Colour terms and national flags

I’m currently writing an article on the relationship between language and social features of the speakers who use it. As studies such as Lupyan & Dale (2010) have discovered, language structure is partially determined by social structure.  However, it’s also probable that many social features of a community are determined by its language.

Today, I wondered whether the number of basic colour terms a language has is reflected in the number of colours on its country’s flag. The idea being that a country’s flag contains colours that are important to its society, and therefore a country with more social tools for discussing colour (colour words) will be more likely to put more colours on its flag. It was a long shot, but here’s what I found:

The World Atlas of Language Structures has data on the number of basic colours in many languages (Kay & Maffi, 2008). Wikipedia has a list of country flags by the number of colours in them.  Languages with large populations (like English, Spanish etc.) were excluded.  It’s known that the number of basic colour terms correlates with latitude, so a partial correlation was carried out.  There was a small but significant relationship between the number of colour terms in a langauge and the number of colours on the flag where that language is spoken (r = 0.15, τ = 254, p=0.01, partial correlation, 2-tailed using Kendall’s tau).

Here’s the flag of Belize, where Garífuna is spoken (9-10 colours in the language, 12 colours on the flag):

Here is the flag of Nigeria where Ejagham is spoken (3-4 colours in the langauge, 2 colours on the flag):

Interestingly, the languages with the highest number of colours in their language and flag come from Central America while the majority of the languages with the lowest number of colours in their language and flag come from Africa.  Maybe there’s some cultural influence on neighbouring flags.

Update:

Here’s a boxplot, which makes more sense:

Also, I re-ran the analysis taking into account distance from the equator, speaker population and some properties of the nearest neighbour of each language (number of colours on flag and number of basic colours in langauge).  A multiple regression showed that the number of basic colours in a language is still a significant predictor of the number of colours in its national flag (r = 0.12, F(106,16)=1.8577, p= 0.03).  This analysis was done by removing languages with populations more than 2 standard deviations from the mean (9 languages out of 140).  The relationship is still significant with the whole dataset.

There are still problems with this analysis, of course.  For example, many of the languages in the data are minority languages which may have little impact on the national identity of a country.  Furthermore, the statistics may be compromised by multiple comparisons, since there may be a single flag for more than one language.  Also, a proper measure of the influence of surrounding languages would be better.  The nearest neighbour was supposed to be an approximation, but could be improved.

Lupyan G, & Dale R (2010). Language structure is partly determined by social structure. PloS one, 5 (1) PMID: 20098492

Kay, Paul & Maffi, Luisa. (2008). Number of Basic Colour Categories.In: Haspelmath, Martin & Dryer, Matthew S. & Gil, David & Comrie, Bernard (eds.) The World Atlas of Language Structures Online. Munich: Max Planck Digital Library, chapter 133.

Animal Signalling Theory 101: Handicap, Index… or even a signal? The Case of Fluctuating Asymmetry

The differences between handicaps and indices are usually distinguishable in formal mathematical models or in unambiguous real-world cases. Often though, classifying a trait as a handicap, an index, or even a signal at all, can be quite a difficult task.

For the purposes of illustration I will use Fluctuating Asymmetry (FA for short) as an example.  Fluctuating asymmetry is the term used to refer to deviation from symmetry in paired morphological structures (ranging from birds’ tails to human faces) that should be, all being well, bilaterally symmetric. Deviations from the ideal symmetrical phenotype are caused by inherent genetic perturbations and exposure to environmental disturbances occurring in early development.

Is FA a signal?

In their 2005 book Animal Signals, Maynard-Smith and Harper define a signal as:

‘Any act or structure which alters the behaviour of other organisms, which evolved because of that effect, and which is effective because the receiver’s response has also evolved’

They then argue that FA is unlikely to function as a signal because it is difficult to discern whether receivers respond directly to FA and because there appear to be few examples of displays in which signallers actively advertise their symmetry to receivers.

 

Continue reading “Animal Signalling Theory 101: Handicap, Index… or even a signal? The Case of Fluctuating Asymmetry”

Cultural inheritance in studies of artifical grammar learning

Recently, I’ve been attending an artificial language learning research group and have discovered an interesting case of cultural inheritance.  Arthur Reber was one of the first researchers to look at the implicit learning of grammar.  Way back in 1967, he studied how adults (quaintly called ‘Ss’ in the original paper) learned an artificial grammar, created from a finite state automata.  Here is the grand-daddy of artificial language learning automata:

Continue reading “Cultural inheritance in studies of artifical grammar learning”

The emergence of stable bilingualism in the lab: An experiment proposal

There is a huge amount of linguistic diversity in the world. Isolation and drift due to cultural evolution can explain much of this, but there are many cases where interacting groups use several languages. In fact, by some estimates, bilingualism is the norm for most societies. If one views language as a tool for communicating about objects and events, it seems strange that linguistic diversity should be maintained over time for two reasons. First, it seems more efficient, during language use, to have a one-to-one mapping between signals and meanings. In fact, mutual exclusivity is exhibited by young children and has been argued to be an innate bias and crucial to the evolution of a linguistic system. How or why do bilinguals over-ride this bias? Secondly, learning two language systems must be more difficult than learning one. What is the motivation for expending extra effort on learning an apparently redundant system?

Despite these obstacles, stable bilingualism exists in many parts of the world.   How might these arise and be maintained?  Continue reading “The emergence of stable bilingualism in the lab: An experiment proposal”

Emergence of linguistic diversity in the lab

There is a huge amount of linguistic diversity in the world. Isolation and drift due to cultural evolution can explain much of this, but there are many cases where linguistic diversity emerges and persists within groups of interacting individuals.  Previous research has identified the use of linguistic cues of identity as an important factor in the development of linguistic diversity (e.g. Nettle, 1999).  Gareth Roberts looks at this issue with an experimental paradigm.

This experiment was a game where individuals had to trade commodities in a series of rounds. At each round, individuals were paired up either with a team-mate or a competitor, though the speaker’s true identity was hidden.  Players were given random resources, but scored points based on how ‘balanced’ their resources were after trading (that is, you were punished for having much more meat than corn, for example).  A commodity given to another individual was worth twice as much to the receiver as to the donor.

Players could only interact through an ‘alien’ language via an instant-messaging system.  Prior to the game, individuals learned an artificial language which they were to use in these interactions. All participants were initially given the same starting language.  There were several conditions that manipulated the frequency with which you interacted with your team-mate and whether the task was competitive or co-operative.  In the co-operative condition, four players were considered as part of the same team and the task was to get a high a score as possible.  In the competitive condition the four players were split into two groups and the task was to score more than the other team.  In this condition, then, the main task was to identify whether your partner was a co-operator or a competitor.

The results showed that, if players interacted frequently enough with their team-mates and were in competition with another group, then linguistic diversity emerged.  Over the course of the game each team developed its own ‘variety’, and this was used as a marker of group identity. For example, in one game two forms of the word for ‘you’ arose.  Players in one team tended to use ‘lale’ while players in the other team tended to use ‘lele’, meaning that players could tell group membership from this variation.  Thus, linguistic variation arose due to the linguistic system evolving to encode the identity of the speakers.

The diversity seemed to arise both from drift and intentional change, both of which have been documented in the sociolinguistic literature.  Roberts suggests that linguistic markers make good social markers because they are costly to obtain (so difficult for free-riders to fake), salient and flexible enough to cope with changing group dynamics.  In the next post, I’ll be thinking about a similar experiment looking at how linguistic variation might arise in a co-operative scenario.

Roberts, G. (2010). An experimental study of social selection and frequency of interaction in linguistic diversity Interaction Studies, 11 (1), 138-159 DOI: 10.1075/is.11.1.06rob

The Interrogative Mood: A Novel?

Just a quick post in case folks haven’t heard about this already, I got a copy for Christmas.

‘The Interrogative Mood: A Novel?’ by Padgett Powell – A book composed entirely of interrogative sentences, or rather, questions.

It has been hailed as a pioneering yet risky step in the author’s somewhat turbulent writing career, but has received praise from a puzzled many people who have found an unexpected enjoyment and intrigue in its pages, for example:

‘How this book works is beyond me, but, miraculously, it does’ (Village Voice)

‘It is a wondrous strange… a hydra-headed reflection of life as it experienced, and of thought as it is felt’ (New York Times Book Review)

The book is not the first of its kind – ‘Gold Fools’ by fellow American novelist Gilbert Sorrentino is also completely written in interrogative sentences, and tells a Western adventure story whilst challenging and questioning genre-specific stereotypes and contemporary linguistic convention.

Even so, Powell’s book is still unique because it was written to achieve a different objective. Unlike ‘Gold Fools’ there is no chronological story to this ‘novel’ – Powell calls upon every sentence forming configuration in English to dispense vast stores of accrued knowledge, factual information, tantalising and mysterious hints about himself, his memories, and his life. Some interrogatives are curt and challenging, where as others span the length of paragraphs and pages thanks to some pretty serious sentence embedding. Through an agreeable barrage of dos, ifs, ares and all the WH-words, Powell not only covertly feeds us information about himself, but forces us to think deep into the worlds of ourselves and those around us. He presents the reader with moral dilemmas interspersed with comparably routine queries, encouraging us to consider how we might behave faced with a variety of arbitrary and significant choices, highlighting both humorous and perturbing inconsistencies in every arena of life.

Direction and premeditated structure is not immediately apparent in the novel (something to be examined, maybe?) and this works as a selling point. The reader is engaged by Powell’s gentle and inquisitive bullying which encourages self examination, reflection, and increased time spent on Wikipedia trying to source some obscure reference or fact.

A warning though – reading this book hijacks the internal narrative, forcing you to think almost entirely in interrogatives for a good few hours afterwards.