Language structure is partly determined by social structure.

Abstract

Languages differ greatly both in their syntactic and morphological systems and in the social environments in which they exist. We challenge the view that language grammars are unrelated to social environments in which they are learned and used.
We conducted a statistical analysis of >2,000 languages using a combination of demographic sources and the World Atlas of Language Structures--a database of structural language properties. We found strong relationships between linguistic factors related to morphological complexity, and demographic/socio-historical factors such as the number of language users, geographic spread, and degree of language contact. The analyses suggest that languages spoken by large groups have simpler inflectional morphology than languages spoken by smaller groups as measured on a variety of factors such as case systems and complexity of conjugations. Additionally, languages spoken by large groups are much more likely to use lexical strategies in place of inflectional morphology to encode evidentiality, negation, aspect, and possession. Our findings indicate that just as biological organisms are shaped by ecological niches, language structures appear to adapt to the environment (niche) in which they are being learned and used. As adults learn a language, features that are difficult for them to acquire, are less likely to be passed on to subsequent learners. Languages used for communication in large groups that include adult learners appear to have been subjected to such selection. Conversely, the morphological complexity common to languages used in small groups increases redundancy which may facilitate language learning by infants.
We hypothesize that language structures are subjected to different evolutionary pressures in different social environments. Just as biological organisms are shaped by ecological niches, language structures appear to adapt to the environment (niche) in which they are being learned and used. The proposed Linguistic Niche Hypothesis has implications for answering the broad question of why languages differ in the way they do and makes empirical predictions regarding language acquisition capacities of children versus adults.

Full text

Page 1

Language Structure Is Partly Determined by Social
Structure
Gary Lupyan1*, Rick Dale2
1Institute for Research on Cognitive Science and Center for Cognitive Neuroscience, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America,
2Department of Psychology, The University of Memphis, Memphis, Tennessee, United States of America
Abstract
Background: Languages differ greatly both in their syntactic and morphological systems and in the social environments in
which they exist. We challenge the view that language grammars are unrelated to social environments in which they are
learned and used.
Methodology/Principal Findings: We conducted a statistical analysis of .2,000 languages using a combination of
demographic sources and the World Atlas of Language Structures— a database of structural language properties. We found
strong relationships between linguistic factors related to morphological complexity, and demographic/socio-historical
factors such as the number of language users, geographic spread, and degree of language contact. The analyses suggest
that languages spoken by large groups have simpler inflectional morphology than languages spoken by smaller groups as
measured on a variety of factors such as case systems and complexity of conjugations. Additionally, languages spoken by
large groups are much more likely to use lexical strategies in place of inflectional morphology to encode evidentiality,
negation, aspect, and possession. Our findings indicate that just as biological organisms are shaped by ecological niches,
language structures appear to adapt to the environment (niche) in which they are being learned and used. As adults learn a
language, features that are difficult for them to acquire, are less likely to be passed on to subsequent learners. Languages
used for communication in large groups that include adult learners appear to have been subjected to such selection.
Conversely, the morphological complexity common to languages used in small groups increases redundancy which may
facilitate language learning by infants.
Conclusions/Significance: We hypothesize that language structures are subjected to different evolutionary pressures in
different social environments. Just as biological organisms are shaped by ecological niches, language structures appear to
adapt to the environment (niche) in which they are being learned and used. The proposed Linguistic Niche Hypothesis has
implications for answering the broad question of why languages differ in the way they do and makes empirical predictions
regarding language acquisition capacities of children versus adults.
Citation: Lupyan G, Dale R (2010) Language Structure Is Partly Determined by Social Structure. PLoS ONE 5(1): e8559. doi:10.1371/journal.pone.0008559
Editor: Dennis O’Rourke, University of Utah, United States of America
Received October 12, 2009; Accepted December 4, 2009; Published January 20, 2010
Copyright: ? 2010 Lupyan, Dale. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: GL was supported by an Integrative Graduate Education and Research Training (IGERT) award to the Institute for Research in Cognitive Science,
University of Pennsylvania. RD was supported by National Science Foundation BCS-0720322 and BCS-0826825. The funders had no role in study design, data
collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
* E-mail: lupyan@sas.upenn.edu
Introduction
Although the largest languages are spoken by millions of people
spread over vast geographic areas, most languages are spoken by
relatively few individuals over comparatively small areas. The
median number of speakers for the 6,912 languages catalogued by
the Ethnologue is only 7,000, compared to the mean of over
828,000 [1]. Similarly, for the 2,236 languages in our sample
(Figure 1), the median area over which a language is spoken is
about the size of Luxembourg or San Diego, California (948 km2).
The mean area is about the size of Austria or the US state of
Maryland (33,795 km2). Languages also differ dramatically in the
proportion of individuals who speak the language natively (L1
speakers) to those who learned it later in life (L2 speakers) (Table
S1). Although there are numerous counter-examples (Text S1),
languages spoken by millions of people have a greater likelihood of
coming into contact with other languages and of having numerous
nonnative speakers compared to languages spoken by only a few
thousand people. This is not surprising: a language spoken by
more people is more likely to encompass a larger and more diverse
area and include speakers from varying ethnic and linguistic
backgrounds. Conversely, languages spoken by a thousand or even
fewer individuals tend to be spoken in highly circumscribed locales
(Text S2). Overall, languages with smaller speaker populations are
more likely to be spoken by more socially cohesive groups [2] than
languages that have millions of speakers.
Just as there are socio-historical and demographic differences
among the world’s languages, there are also vast differences
among languages in morphology and syntax [3]. For example
languages differ in the devices used to convey syntactic relations—
who did what to whom. Some languages rely on a fixed word
order (Subject-Verb-Object in the case of English), while other
languages (e.g., German, Polish) allow much more flexibility in
word order and rely on case markings to signal which noun fills the
PLoS ONE | www.plosone.org1January 2010 | Volume 5 | Issue 1 | e8559

Page 2

role of subject, object, etc. [4] More generally, languages differ in
the amount of information conveyed through inflectional mor-
phology compared to the amount of information conveyed
through non-morphological devices such as word order and
lexical constructions. For example, compare morphological
marking of aspect in Russian ‘‘Ya vypil chai’’ (I PERFECTIVE+-
drank tea), to the English lexical strategy, ‘‘I finished drinking the
tea.’’ Some other domains exhibiting such differences between
lexical and morphological strategies include tense, aspect,
evidentiality, negation, plurality, and expressions of possibility.
Languages with richer morphological systems are said to be
more overspecified [5–7]. For instance, of the languages that
encode the past tense inflectionally, about 20% have past tenses
that explicitly mark remoteness distinctions. For example Yagua, a
language of Peru, has inflections that differentiate 5 levels of
remoteness. A verb denoting an event that happened only a few
hours ago takes the suffix –ja ´siy; an event that happened a day
previous to the utterance requires a different suffix, -jay; an event
that occurred a week to a month ago, a still different suffix, -siy,
etc. [8]. Of course, languages without these grammatical
distinctions can express them lexically, as in English: ‘‘I broke
my foot a few years ago.’’ On the other hand, when semantic
distinctions are encoded grammatically, speakers are generally
obligated to make them [9], hence sentences concerning the past
will have its remoteness specified even when it may not be relevant
to the discourse. In the English example above, speakers have the
option to omit remoteness information, but are obligated to
express the grammatically encoded past tense (which leaves
remoteness to context). In Mandarin or Thai, which express both
tense and remoteness lexically, speakers have the option of
omitting the past tense entirely. Of the 222 languages in our
corpus for which tense information is available, 40% do not
encode past tense inflectionally [10].
The degree and specificity of morphological encoding can reach
astounding levels. For example, Karok—a language of N.W.
California—has morphological suffixes for forms of containment
pa:h-kirih ‘‘throw into fire’’, pa:h-kurih ‘‘throw into water’’, pa:h-
ruprih ‘‘throw in through a solid’’ (the affixes are unrelated to the
lexemes for water, fire, etc.) [11]. Clearly, such elaboration does
not arise from communicative necessity. Researchers have long
been puzzled by the reasons why some languages abound in such
overspecification, while others (sometimes closely related ones)
eschew it. For example, in comparing English and German we
find that where the surface structures of English and German
contrast, English is less specified, leaving more to context [6], thus,
‘‘…German speakers are forced to make certain semantic
distinctions which can regularly be left unspecified in English’’
[6], p. 28). For example, German obligatorily specifies the
direction of motion in the place adverbs here/there/where.
Compare: hier/her; dort/hin; wo/wohin. English can specify direction
using to and from (‘‘where to’’ versus ‘‘where from’’), but such
specification is optional and is generally omitted [12,9]. Gram-
matical divergence between languages has been typically attribut-
ed to drift—as a population speaking an ancestral Germanic
language splits into separate groups, their language gradually
diverges with one branch becoming English and the other German
[13]. Such accounts do not explain why English came to shed
much of its morphology while German retained it.
Attempts to establish relationships between social and linguistic
structure date back at least a century [14–16]; see [17] for a
review. Recent work has provided some support for the idea that
extralinguistic factors (e.g., degree of ecological risk) play a role in
some aspects of language such as varying levels of linguistic
diversity in different parts of the world [18,19]. A number of
researchers have investigated correlations between social environ-
ments and the phonological structure of languages [20–22] and,
intriguingly, have also found correlations between physical aspects
of the environment such as temperature, and phonological
inventories [23,24]. It has also been argued that the physical
environment [25], and historical developments that impact
language transmission can impact the syntactic and morphological
structure of languages [2,5,26,27].
Languages with histories of adult learning have been argued to
be morphologically simpler, less redundant, and more regular/
transparent [2,7,28–30]. This argument has been made most
forcefully and convincingly for Creole languages [26], but it has
been speculated that any situation in which a language is learned
by a substantial number of adults it becomes simplified due to the
‘‘lousy language learning abilities of the human adult’’ [28]. The
evidence for such linguistic simplification has been largely
descriptive, consisting of selected examples and grammatical
inventories of small numbers of languages [17,14,29,7,5] . Thus,
at present, there is little convincing evidence of global relationships
between linguistic structure and non-linguistic factors and limited
theoretical frameworks within which to understand such relation-
ships [e.g., 20 for the case of phonological inventories]. An
additional limitation of previous work is that it fails to explain why
morphological complexity and grammatical overspecification arise
in the first place. That is, why aren’t all languages as
morphologically simple as those that have been argued to be
heavily shaped by adult learning, e.g., English [12]?
The primary goal of the present work is to examine whether
non-spurious relationships exist between social and linguistic
structure by using large-scale demographic and linguistic databas-
es. A secondary goal is to provide a tentative framework within
which to understand the reported results—the Linguistic Niche
Hypothesis—which provides a nomothetic account for understand-
ing relationships between linguistic and social structure (Text S3).
In assessing the relationship between social and linguistic
structure, it is useful to distinguish two main contexts (niches) in
which languages are learned and used: the exoteric and the esoteric
[2,31]. The exoteric linguistic niche contains languages with
large numbers of speakers, thus requiring these languages to
serve as interfaces for communication between strangers. In
Figure 1. Geographic distribution of the 2,236 languages
included in the present study.
doi:10.1371/journal.pone.0008559.g001
Social & Linguistic Structure
PLoS ONE | www.plosone.org2January 2010 | Volume 5 | Issue 1 | e8559

Page 3

reality the esoteric and exoteric niches form a continuum, and
are represented as such in our analyses (see also Text S4).
Speakers of languages in the exoteric niche compared to
speakers of esoteric languages are more likely to (1) be nonnative
speakers or have learned the language from nonnative speakers,
and (2) use the language to speak to outsiders—individuals from
different ethnic and/or linguistic backgrounds. The exoteric
niche includes languages like English, Swahili, and Hindi, while
the esoteric niche includes languages like Tatar, Elfdalian,
and Algonquin.
Results
To assess relationships between social and linguistic structure we
constructed a dataset that combined social/demographic and
typological information for 2,236 languages. Grammatical infor-
mation was obtained from the World Atlas of Language Structures
(WALS) [32]—a database of structural properties of language
compiled from descriptive materials such as reference grammars.
The full dataset was constructed by combining typological data
from WALS with the following demographic variables: speaker
population, geographic spread, and number of linguistic neighbors
derived from Ethnologue [1] and the Global Mapping Institute
[33] (see Text S5, containing analyses that demonstrate represen-
tativeness of the sample). Although WALS includes over 2,000
languages, most languages are only defined on a small number of
linguistic features.
Table 1 shows the results of three models used to explore the
relationships between typological features, and measures of
population, geographic spread, and degree of linguistic contact.
Population, and to a lesser extent area and number of neighboring
neighbors, was a significant predictor for 26/28 of the WALS
features that were most relevant to inflectional morphology. Of
these, 23 remained significant when language family was partialed
out. For 22/28 the demographic variables (population, area over
which a language is spoken, and degree of linguistic contact)
combined with geographic covariates (latitude/longitude) proved
to be better predictors of the linguistic features than geographic
location alone. Across a wide range of linguistic features, a
systematic relationship (discussed below) between demographic
and typological variables was found, providing overwhelming
evidence against the null hypothesis that language structure is
unrelated to socio-demographic factors. Although the three
demographic predictors are not independent (intercorrelations
range from .5 to .6), including all three predictors helps to ensure
that linguistic-demographic relationships are not spurious. We
summarize the findings below (parentheticals refer to entries in
Table 1). Text S6 includes more detailed descriptions of the
linguistic features.
Compared to languages spoken in the esoteric niche (smaller
population, smaller area, fewer linguistic neighbors), languages
spoken in the exoteric niche:
1. Are more likely to be classified by typologists as isolating
languages—those in which grammatical functions are fulfilled
by markers not bound to the stem (e.g., modals, lexical items,
or particles) than fusional languages—those in which grammat-
ical markers show a greater degree of fusion to the stem (e.g.,
affixes and clitics) (1–2).
2. Contain fewer case markings (3), and have case systems with
higher degree of case syncretism (4) (further reducing the
number of morphological distinctions). Nominative/accusative
alignment is more prevalent than ergative/absolutive align-
ment (5).
3. Have fewer grammatical categories marked on the verb (6) and
are less likely to have idiosyncratic verbal morphology such as
verbal person markings that alternate between marking agent
or patient depending on semantic context (7).
4. Are more likely to not possess noun/verb agreement or have
agreement limited to agents (8) and are more likely to possess
no person markings on adpositions (9). As with case markings,
syncretism in noun/verb/adposition agreement is more
common in languages spoken in the exoteric niche (10).
5. Are more likely to make possibility and evidentiality distinc-
tions using lexical (e.g., verbal) constructions rather than using
inflections such as affixes (11,12,14) and are more likely to
conflate the two (semantically distinct) types of possibility (13).
6. (a) Are more likely to encode negation using analytical
strategies (negative word) than using inflections (affixes) and
are less likely to have idiosyncratic variations between word
and affixation strategies (15). (b) Are more likely to have
obligatory plural markers (16). For languages with optional
markers, analytic (lexical) strategies are more common than
inflectional strategies (affixes or clitics). (c) Are less likely to have
a separate associative plural (e.g., ‘‘He and his friends’’) (17) (c)
Are more likely to have a dedicated question particle (18).
7. (a) Are less likely to encode the future tense morphologically
(19) or possess remoteness distinctions in the past tense (20).
Languages spoken in the exoteric niche are somewhat more
likely to mark the perfective/imperfective distinction in their
morphology (21), although this relationship disappears when
language geography is partialed out. (b) Are more likely to
mark singular imperatives on verbs using inflections than
have no morphological markings for imperatives at all, but
are less likely to contain more elaborate markings that
differentiate between singular and plural imperatives (22).
(c) Are less likely to have inflections that mark possession
(23). If possession is marked, it is less likely to distinguish
between types of possession (e.g., alienable versus inalien-
able) (24). (d) Are less likely to morphologically mark the
optative mood (25).
8. Are less likely to have definite and indefinite articles (26). If
both are present, they are more likely to be expressed by
separate words than affixes.
9. Are less likely to communicate distance distinctions in
demonstratives (27).
10.Are more likely to express pronominal subjects lexically
than morphologically (28).
Figure 2 displays features 9, 19, and 23 from Table 1. For
each, languages with greater populations are more likely to use a
less morphologically complex strategy. Figure S1 shows the
relationship between population and two quantitative measures of
morphological complexity: number of case markings (feature 3),
and inflectional synthesis of the verb (feature 6). Both relation-
ships are significant as analyzed by a GLM : cases, P=.018;
inflectional synthesis of the verb: P,.00005 (the relationship
remains significant when no-case languages are removed: P=.04)
(Figure S1).
We constructed a morphological complexity measure by
summing the number of features for which each language relies
on lexical versus morphological coding and subtracting the total
from 0. There was a strong relationship between complexity and
speaker population, p,.00005 (Figure 3). Languages with the most
speakers were more likely to be less morphologically rich, using
lexical over morphological strategies for encoding semantic and
syntactic distinctions.
Social & Linguistic Structure
PLoS ONE | www.plosone.org3January 2010 | Volume 5 | Issue 1 | e8559

Page 4

Table 1. Model fits are the Aikake information criteria of models predicting the linguistic feature from just the language family,
from population alone, and from the three demographic variables, respectively.
Model
FeatureObserved Pattern
Population
(Log
Speakers)
Area
(Log
km2)
Ling Contact
(Log ling.
neighbors)Model Fits
Morphological Type
1.Fusion of inflectional formatives (20) 1
Isolating . Concatenating**
x. 358/138/140
2. Inflectional Morphology(26) 1
Little or None . Present **.. 688/678/680
Cases
3. Number of Cases (49) 1 (see Figure S1) Fewer Cases . More Cases **
xx 795/920/912
4.Case Syncretism (28) 1
Core/Non-Core Cases . Core Only=No Syncretism
e
ee
103/89/93
5. Alignment of Case markings of Full NPs (98) 1
Nom/Acc . Erg/Abs **
** ** 437/348/349
Verb Morphology
6.Inflectional Synthesis of the Verb (categories
per word)(22) 1 (See Figures 4–5; S1)
Few Forms . Many Forms**
**** 450/451/454
7.Alignment of Verbal Person Marking (100) 1
Neutral $ Ergative=Accusative . Context Dependent****x1083/818/821
Agreement
8. Person Marking on Verbs (102)None=Agent . Agent & Patient=Patient
Only . Agent or Patient
** ** ** 1373/911/923
9. Person Marking on Adpositions
(48) 1(see Figure 2A)
None . Pronoun . Pronoun + Noun **
e1
**640/498/495
10.Syncretism in Verbal Person/Number
Marking (29)
Syncretic . None **
e
**207/184/188
Possibility and Evidentials
11.Situational Possibility (74) 1
Verbal . Morphological**
****250/246/249
12.Epistemic Possibility (75) 1
Verbal . Morphological**
****177/112/112
13. Overlap b/w Epistemic and
Situational Possibility (76) 1
Situational/Epistemic Collapsed . Separate Markers **
e
** 501/350/350
14.Coding of Evidentiality (77)No Gram. Evidentials . Gram. Evidentials **
.. 497/536/537
Negation, Plurality, Interrogatives
15.Coding of Negation (112) 1
Word . Affix $ Double Neg $ Particle $ Aux.
Verb $ Word/Affix Variation
**
** ** 2961/2454/2468
16.Coding/Occurrence of Plurality (34) 1
Obligatory . Optional [word . affix/clitic] . None **
ee
1055/807/816
17.Associative Plural (36) 1
No assoc. Plural . Assoc. Plural
e
.. 200/201/205
18.Polar Question coding (92) 1
Question particle . No Question particle **
****1022/979/979
Tense, Possession, Aspect, Mood
19.Future Tense (67) 1 (see Figure 2B)No Morph . Morph.**
ee
320/295/294
20.Past Tense (66) 1
Simple Past . No Morph Past . 2–3
Remoteness Dist. . 3+ Remoteness Dist.
**
e1
e
617/466/458
21.Perfective/Imperfective (65) Morph. Distinction . No Morph Distinction
e
e
. 330/303/304
22.Morphological Imperative (70)Sing only . Not Morph. Marked $
Sing & Plural $ Sing. Syncretic with Plural
**
xx 1395/1228/1223
23. Coding of Possessives (57) 1 (see Figure 2C) No possessive affix . Possessive Affix **
****757/826/828
24. Possessive Classification (59)1
No classification . 2 Classes . 3–5 Classes **
** **514/477/480
25.Optative (73) 1
Not Marked . Morphologically Marked.**1
x264/264/250
Articles, Demonstratives, Pronouns
26. Definite/Indefinite Articles (38–39) 1
None $ Both (Lexical)=Only Def. or Only
Indef. $ Both (Affixes)
.**1
.1359/1178/1169
27.Distance distinctions in demonstratives (41)No distance contrasts . 2 Contrasts $ 2+ Contrasts**
.**501/471/474
28.Expression of Pronominal Subjects (101) 1
Oblig. Lexical=Opt. Lexical . Affixes/Clitics **
e
** 1102/1011/1012
Smaller values indicate better fits.
1=Demographics and geographic location predict typology better than geographic location alone (x2 model comparison (p,.05).
=Predictive power of population is reduced (significantly larger residual deviations) by randomly shuffling languages within their families. Indicates that reported
effects generalize to within language families.
**=Reported pattern is significant (p between 0.05 and 10–11) after controlling for language family.
e=Pattern no longer significant (p$.05) after controlling for language family.
1=Area and Number of Neighbors are significant predictors controlling for population.
.=Consistent with the pattern reported, but not significant.
x=Pattern after controlling for geographic covariates is non-significantly inconsistent with the pattern observed without controlling for geographic location.
doi:10.1371/journal.pone.0008559.t001
Social & Linguistic Structure
PLoS ONE | www.plosone.org4January 2010 | Volume 5 | Issue 1 | e8559

Page 5

In cross-cultural or -linguistic research, it is important to
consider the issue of non-independence of cases, often subject to
autocorrelation (also known as Galton’s problem). We controlled
for non-independence in several ways:
(1) We factored in both language family and geographic location to
ensure they did not completely account for the observed
language feature distribution (e.g., Figure 2, right panels). Thus,
although most linguistic features are subject to strong areal
effects, theseeffects cannot explain the observed findings. Taking
as an example one feature (inflectional synthesis of the verb,
feature 6), Figure 4 shows the results averaged by the largest
language families (Figure 4a, Pearson r=.48) and by continents
(Figure 4b, Pearson r=.96). Figure 5 shows the within-family
data for the 6 largest language families in our sample. The
relationship with population was significant for each major
family (excepting the Australian family which has a very small
population range) (see supplementary materials and methods).
(2) We also performed a Monte Carlo simulation, randomizing
language-demographic information within language family. As
shown in Table 1 (
symbols), randomizing within-language
family significantly reduces the predictive power of population
for 22/28 features.
These controls ensure that the present results cannot be
explained as consequences of historical events such as the
Figure 2. Three features demonstrating the relationship between population and morphological encoding. Y-axis of right-side panels
displays residual population after the GLM model partialed out geographic information (reducing the correlation between population and geography
to 0). Values above bars represent the number of languages coded for that feature value. (A) Adpositions (prepositions or postpositions) may be
coded for person agreement in some languages. In English, there is no such agreement/person marking. One may say ‘‘from him’’ without, for
example, encoding onto ‘‘from’’ the gender or number identity of ‘‘him,’’ as opposed to ‘‘me’’ in ‘‘from me.’’ Languages that do encode more
information on adpositions show smaller populations. (B) Languages that use inflections (i.e., morphology) for the future tense have smaller
populations. (C) Morphological encoding of possession is associated with smaller populations of speakers.
doi:10.1371/journal.pone.0008559.g002
Social & Linguistic Structure
PLoS ONE | www.plosone.org5January 2010 | Volume 5 | Issue 1 | e8559