Why do human beings speak so manylanguages?17 July 2017, by Michael Gavin

People currently speak 7,000 languages around theglobe. Credit: Michael Gavin, CC BY-ND

The thatched roof held back the sun's rays, but itcould not keep the tropical heat at bay. Aseveryone at the research workshop headedoutside for a break, small groups splintered off togather in the shade of coconut trees and enjoy abreeze. I wandered from group to group, joining inthe discussions. Each time, I noticed that thelanguage of the conversation would change froman indigenous language to something they knew Icould understand, Bislama or English. I wasamazed by the ease with which the meeting'sparticipants switched between languages, but Iwas even more astonished by the number ofdifferent indigenous languages.

Thirty people had gathered for the workshop onthis island in the South Pacific, and all except forme came from the island, called Makelua, in thenation of Vanuatu. They lived in 16 differentcommunities and spoke 16 distinct languages.

In many cases, you could stand at the edge of one

village and see the outskirts of the next community.Yet the residents of each village spoke completelydifferent languages. According to recent work bymy colleagues at the Max Planck Institute for theScience of Human History, this island, just 100kilometers long and 20 kilometers wide, is home tospeakers of perhaps 40 different indigenouslanguages. Why so many?

We could ask this same question of the entireglobe. People don't speak one universal language,or even a handful. Instead, today our speciescollectively speaks over 7,000 distinct languages.

And these languages are not spread randomlyacross the planet. For example, far more languagesare found in tropical regions than in the temperatezones. The tropical island of New Guinea is hometo over 900 languages. Russia, 20 times larger, has105 indigenous languages. Even within the tropics,language diversity varies widely. For example, the250,000 people who live on Vanuatu's 80 islandsspeak 110 different languages, but in Bangladesh,a population 600 times greater speaks only 41languages.

Why is it that humans speak so many languages?And why are they so unevenly spread across theplanet? As it turns out, we have few clear answersto these fundamental questions about howhumanity communicates.

Some ideas, but little evidence

Most people can easily brainstorm possibleanswers to these intriguing questions. Theyhypothesize that language diversity must be abouthistory, cultural differences, mountains or oceansdividing populations, or old squabbles writ large –"we hated them, so we don't talk to them."

1 / 5

Map of Australia’s 406 languages before contact withEuropeans. Claire Bowern, Yale University, with supportfrom the National Science Foundation BCS-1423711, CCBY

The questions also seem like they should befundamental to many academic disciplines –linguistics, anthropology, human geography. But,starting in 2010, when our diverse team ofresearchers from six different disciplines and eightdifferent countries began to review what wasknown, we were shocked that only a dozenprevious studies had been done, including one weourselves completed on language diversity in thePacific.

These prior efforts all examined the degree towhich different environmental, social andgeographic variables correlated with the number oflanguages found in a given location. The resultsvaried a lot from one study to another, and no clearpatterns emerged. The studies also ran up againstmany methodological challenges, the biggest ofwhich centered on the old statistical adage –correlation does not equal causation.

We wanted to know the exact steps that led to somany languages forming in certain places and sofew in others. But previous work provided fewrobust theories on the specific processes involved,and the methods used did not get us any closer tounderstanding the causes of language diversitypatterns.

For example, previous studies pointed out that atlower latitudes languages are often spoken acrosssmaller areas than at higher latitudes. You can fitmore languages into a given area the closer youget to the equator. But this result does not tell usmuch about the processes that create languagediversity. Just because a group of people crossesan imaginary latitudinal line on the map doesn'tmean they'll automatically divide into two differentpopulations speaking two different languages.Latitude might be correlated with languagediversity, but it certainly did not create it.

Can a simple model predict reality?

A better way to identify the causes of particularpatterns is to simulate the processes we think mightbe creating them. The closer the model's productsare to the reality we know exists, the greater thechances are that we understand the actualprocesses at work.

Two members of our group, ecologists ThiagoRangel and Robert Colwell, had developed this simulation modeling technique for their studies of species diversity patterns. But no one had everused this approach to study the diversity of humanpopulations.

We decided to explore its potential by first buildinga simple model to test the degree to which a fewbasic processes might explain language diversitypatterns in just one part of the globe, the continentof Australia.

2 / 5

The simulation model predicts virtually the same numberof languages (407) as were observed in reality (406).Credit: Gavin et al DOI: 10.1111/geb.12563, CC BY

Our colleague Claire Bowern, a linguist at YaleUniversity, created a map that shows the diversityof aboriginal languages – a total of 406 – found inAustralia prior to contact with Europeans. Therewere far more languages in the north and along thecoasts, with relatively few in the desert interior. Wewanted to see how closely a model, based on asimple set of processes, could match thisgeographic pattern of language diversity.

Our simulation model made only three basicassumptions. First, populations will move to fillavailable spaces where no one else lives.

Second, rainfall will limit the number of people thatcan live in a place; Our model assumed that peoplewould live in higher densities in areas where itrained more. Annual precipitation varies widely inAustralia, from over three meters in thenortheastern rainforests to one-tenth of a meter inthe Outback.

Third, we assumed that human populations have amaximum size. Ideal group size is a trade-off

between benefits of a larger group (wider selectionof potential mates) and costs (keeping track ofunrelated individuals). In our model, when apopulation grew larger than a maximum threshold –set randomly based on a global distribution ofhunter-gatherer population sizes – it divided intotwo populations, each speaking a distinct language.

We used this model to simulate language diversitymaps for Australia. In each iteration, an initialpopulation sprung up randomly somewhere on themap and began to grow and spread in a randomdirection. An underlying rainfall map determined thepopulation density, and when the population size hitthe predetermined maximum, the group divided. Inthis way, the simulated human populations grewand divided as they spread to fill up the entireAustralian continent.

Our simple model didn't include any impact fromcontact among groups, changes in subsistencestrategies, the effects of the borrowing of culturalideas or components of language from nearbygroups, or many other potential processes. So, weexpected it would fail miserably.

Incredibly, the model produced 407 languages, justone off from the actual number.

The simulated language maps also show morelanguages in the north and along the coasts, andless in the dry regions of central Australia, mirroringthe geographic patterns in observed languagediversity.

3 / 5

A simulation model based on a few simple processespredicts much of the geographic variation in languagediversity in Australia. Credit: Gavin et al DOI:10.1111/geb.12563, CC BY

And so for the continent of Australia it appears thata small number of factors – limitations rainfallplaces on population density and limits on groupsize – might explain both the number of languagesand much of the variation in how many languagesare spoken in different locations.

Applying the model elsewhere

But we suspect that the patterns of languagediversity in other places may be shaped by differentfactors and processes. In other locations, such asVanuatu, rainfall levels do not vary as widely as inAustralia, and population densities may be shapedby other environmental conditions.

In other instances, contact among human groupsprobably reshaped the landscape of languagediversity. For example, the spread of agriculturalgroups speaking Indo-European or Bantulanguages may have changed the structure ofpopulations and the languages spoken across hugeareas of Europe and Africa, respectively.

Undoubtedly, a wide variety of social andenvironmental factors and processes havecontributed to the patterns in language diversity wesee across the globe. In some places topography,climate or the density of key natural resources maybe more critical; in others the history of warfare,political organization or the subsistence strategiesof different groups may play a bigger role inshaping group boundaries and language diversitypatterns. What we have established for now is atemplate for a method that can be used to uncoverthe different processes at work in each location.

Language diversity has played a key role inshaping the interactions of human groups and thehistory of our species, and yet we know surprisinglylittle about the factors shaping this diversity. Wehope other scientists will become as fascinated by

the geography of language diversity as our researchgroup is and join us in the search for understandingwhy humans speak so many languages.

This article was originally published on TheConversation. Read the original article.

Provided by The Conversation

4 / 5

APA citation: Why do human beings speak so many languages? (2017, July 17) retrieved 3 April 2022from https://phys.org/news/2017-07-human-languages.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, nopart may be reproduced without the written permission. The content is provided for information purposes only.

Powered by TCPDF (www.tcpdf.org)

5 / 5