Grammatical number

Grammatical categories
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In linguistics, grammatical number is a grammatical category of nouns, pronouns, and adjective and verb agreement that expresses count distinctions (such as "one", "two", or "three or more").^[1]

The count distinctions typically, but not always, correspond to the actual count of the referents of the marked noun or pronoun.

The word "number" is also used in linguistics to describe the distinction between certain grammatical aspects that indicate the number of times an event occurs, such as the semelfactive aspect, the iterative aspect, etc. For that use of the term, see "Grammatical aspect".

Overview

Most languages of the world have formal means to express differences of number. One widespread distinction, found in English and many other languages, involves a simple two-way number contrast between singular and plural (car/cars, child/children, etc.). Discussion of other more elaborate systems of number appears below.

Grammatical number is a morphological category characterized by the expression of quantity through inflection or agreement. As an example, consider the English sentences below:

That apple on the table is fresh.

Those two apples on the table are fresh.

The number of apples is marked on the noun—"apple" singular number (one item) vs. "apples" plural number (more than one item)—on the demonstrative, "that/those", and on the verb, "is/are". Note that, especially in the second sentence, all this information can seem redundant, since quantity is already indicated by the numeral "two".

A language has grammatical number when its nouns are subdivided into morphological classes according to the quantity they express, such that:

1. Every noun belongs to a unique number class. (Nouns are partitioned into disjoint classes by number.)
2. Noun modifiers (such as adjectives) and verbs have different forms for each number class and must be inflected to match the number of the nouns to which they refer. (Number is an agreement category.)

This is the case in English: every noun is either singular or plural (a few, such as "fish", can be either, according to context), and at least some modifiers of nouns—namely the demonstratives, the personal pronouns, the articles, and verbs—are inflected to agree with the number of the nouns to which they refer: "this car" and "these cars" are correct, while "*this cars" or "*these car" are ungrammatical and, therefore, incorrect. Only count nouns can be freely used in the singular and in the plural. Mass nouns, like "wine", "silverware", and "wisdom", are normally used in only the singular.^[2] Many languages distinguish between count nouns and mass nouns.

Not all languages have number as a grammatical category. In those that do not, quantity must be expressed either directly, with numerals, or indirectly, through optional quantifiers. However, many of these languages compensate for the lack of grammatical number with an extensive system of measure words.

There is a hierarchy among number categories: no language distinguishes a trial unless having a dual, and no language has dual without a plural.^[3]

Geographical distribution

Obligatory plural marking of all nouns is found throughout western and northern Eurasia and in most parts of Africa. The rest of the world presents a heterogeneous picture. Optional plural marking is particularly common in Southeast and East Asia and Australia, and complete lack of plural marking is particularly found in New Guinea and Australia. In addition to the areal correlations, there also seems to be at least one correlation with morphological typology: Isolating languages appear to favor no or non-obligatory plural marking. This can be seen particularly in Africa, where optionality or absence of plural marking is found particularly in the isolating languages of West Africa.^[4]

Number in specific languages

English

Main article: English plural

English is typical of most world languages, in distinguishing only between singular and plural number. The plural form of a noun is usually created by adding the suffix -(e)s. The pronouns have irregular plurals, as in I versus we, because they are ancient and frequently used words. English verbs distinguish singular from plural number in the third person ("He goes" versus "They go").

Swedish

Swedish inflects nouns in singular and plural. The plural of the noun is usually obtained by adding a suffix, according to the noun's declension. The suffixes are as follows: -or in the 1st declension (e.g. flicka - flickor), -ar in the 2nd (e.g. bil - bilar), -er in the 3rd (e.g. katt - katter), -n in the 4th (e.g. äpple - äpplen) and no inflectional suffix is added for the nouns in the 5th declension (e.g. bord - bord). Verbs in Swedish do not distinguish singular from plural number.

Romance languages

In modern Romance languages, nouns, adjectives and articles are declined according to number (singular or plural only). Verbs are conjugated for number as well as person.

French

In its written form, French declines nouns for number (singular or plural). In speech, however, the majority of nouns (and adjectives) are not for the most part declined for number. This is because the typical plural suffix -s or -es, is silent, and thus does not really indicate a change in pronunciation. Some report that spoken number marking on the noun appears when liaison occurs. This is a misconception. The liaison is heard between the article and the noun, not between the noun and whatever word follows it (e.g. "les avions allemands" is heard as "les zavions allemands" and not as "les avions zallemands"). However:

• some plurals do differ from the singular in pronunciation; for example, masculine singulars in -al [al] typically form masculine plurals in -aux [o].
• Proper nouns are not pluralized, even in writing. (Les voitures, but Les Peugeot 404)

Normally, the article or determiner is the primary indicator of number.

Hebrew

In Modern Hebrew, a Semitic language, most nouns have only singular and plural forms, such as ספר /ˈsɛfɛʁ/ "book" and ספרים /sfaˈʁim/ "books", but some have distinct dual forms using a distinct dual suffix (largely nouns pertaining to numbers or time, such as אלפיים /alˈpajim/ "two thousand" and שבועיים /ʃvuˈajim/ "two weeks"), some use this dual suffix for their regular plurals (largely body parts that tend to come in pairs, such as עיניים /eɪˈnajim/ "eyes", as well as some that do not, such as שיניים /ʃiˈnajim/ "teeth"), and some are inherently dual (such as מכנסיים /mɪxnaˈsajim/ "pants" and אופניים /ofaˈnajim/ "bicycle"). Adjectives, verbs, and pronouns agree with their subjects' or antecedents' numbers, but only have a two-way distinction between singular and plural; dual nouns entail plural adjectives, verbs, and pronouns.

Russian

Modern Russian has a singular vs plural number system, but the declension of noun phrases containing numeral expressions is subject to complex rules. For example, "У меня есть одна книга / три книги / пять книг" ("I have one book-nom.sing. / three book-gen.sing. / five book-gen.plur."). See Dual number: Slavic languages for a discussion of number phrases in Russian and other Slavic languages.

The numeral "one" has a plural form, used with pluralia tantum: одни джинсы / одни часы "one pair of jeans, one clock".^[5]

Finnish

Further information: Finnish grammar#Plurals

The Finnish language has a plural form of every noun case.

talo – house

talot – houses

taloissa – in the houses

However, when a number is used, or a word signifying a number (monta- many), the singular version of the partitive case is used.

kolme taloa – three houses

Types of number

Singular versus plural

Main article: Plural

In most languages with grammatical number, nouns, and sometimes other parts of speech, have two forms, the singular, for one instance of a concept, and the plural, for more than one instance. Usually, the singular is the unmarked form of a word, and the plural is obtained by inflecting the singular. This is the case in English: car/cars, box/boxes, man/men. There may be exceptional nouns whose plural is identical to the singular: one sheep/two sheep.

Singulative versus collective

Main article: Singulative number

Some languages differentiate between an unmarked form, the collective, which is indifferent in respect to number, and a marked form for single entities, called the singulative in this context. For example, in Welsh, moch ("pigs") is a basic form, whereas a suffix is added to form mochyn ("pig"). It is the collective form which is more basic, and it is used as an adjectival modifier, e.g. cig moch ("pig meat", "pork"). The collective form is therefore similar in many respects to an English mass noun like "rice", which in fact refers to a collection of items which are logically countable. However, English has no productive process of forming singulative nouns (just phrases such as "a grain of rice"). Therefore, English cannot be said to have a singulative number.

In other languages, singulatives can be regularly formed from collective nouns; e.g. Standard Arabic حجر ḥajar "stone" → حجرة ḥajara "(individual) stone", بقر baqar "cattle" → بقرة baqara "(single) cow". In Russian, the suffix for forming singulative form is -ин- -in-; e.g. град grad "hail" → градина gradina "hailstone", лёд lyod "ice" → льдина l'dina "block of ice". In both Russian and Arabic, the singulative form always takes on the feminine gender.

Dual

Main article: Dual (grammatical number)

The distinction between a "singular" number (one) and a "plural" number (more than one) found in English is not the only possible classification. Another one is "singular" (one), "dual" (two) and "plural" (more than two). Dual number existed in Proto-Indo-European, persisted in many of the now extinct ancient Indo-European languages that descended from it—Sanskrit, Ancient Greek and Gothic for example—and can still be found in a few modern Indo-European languages such as Slovene. Many more modern Indo-European languages show residual traces of the dual, as in the English distinctions both vs. all, either vs. any, and so on.

Many Semitic languages also have dual number. For instance, in Arabic all nouns can have singular, plural, or dual forms. For non-broken plurals, masculine plural nouns end with ون -ūn and feminine plural nouns end with ات -āt, whilst ان -ān, is added to the end of a noun to indicate that it is dual (even among nouns that have broken plurals).

Pronouns in Polynesian languages such as Tahitian exhibit the singular, dual, and plural numbers.

Trial

The trial number is a grammatical number referring to 'three items', in contrast to 'singular' (one item), 'dual' (two items), and 'plural' (four or more items). Several Austronesian or Austronesian-based languages such as Tolomako, Lihir, Manam, Bislama, and some^[which?] registers^{[citation needed]} of Tok Pisin have trial number in their pronouns; no language is known with trial number in its nouns.^{[citation needed]}

Quadral

The quadral^[6] number, if it existed, would denote four items together, as trial does three. No natural language has it, nor is there any proof that any natural language ever did. It was once thought to exist in the pronoun systems of Marshallese, spoken in the Marshall Islands in the Pacific Ocean,^[7] and in Sursurunga (Hutchisson 1986), in Tangga (Capell 1971:260-262; Beaumont 1976:390), and in several other Austronesian languages. While not all of these languages are adequately attested, it turns out that Sursurunga instead has both a "lesser paucal" (labeled "trial", but in fact referring to small groups, with typically three or four members) and a "greater paucal" (misnamed the "quadral", as it has a minimum of four, e.g. a pair of dyadic kin terms)—the distinction is along the lines of "a few" vs. "several";—and that what Marshallese actually has is a trial and a paucal.^[8] None of them has a "quadral"; in at least two cases the field workers who originally suggested they did have a "quadral" were also the first to publish a peer-reviewed article contradicting that suggestion.

Paucal

Paucal number, for a few (as opposed to many) instances of the referent (e.g. in Hopi, Warlpiri and in Arabic for some nouns). See Quadral and Plural for some examples.

Distributive plural

Distributive plural number, for many instances viewed as independent individuals (for example, in Navajo).

Formal expression of number

Synthetic languages typically distinguish grammatical number by inflection. (Note that analytic languages, such as Chinese, do not have grammatical number.) Some languages have no marker for the plural in certain cases, e. g. Swedish hus --"house, houses" (but huset --"the house", husen --"the houses"). In most languages, the singular is formally unmarked, whereas the plural is marked in some way. Other languages, most notably the Bantu languages, mark both the singular and the plural, for instance Swahili (see example below). The third logical possibility, rarely found in languages, is an unmarked plural contrasting with marked singular. Below are some examples of number affixes for nouns (where the inflecting morphemes are underlined):

• Affixation (by adding or removing prefixes, suffixes, infixes, or circumfixes):
  • Estonian puu "tree, wood" (singular) – puud "the trees, woods" (nominative plural)
  • Finnish: lehmä "cow, the cow" (singular) – lehmät "the cows" (nominative plural)
  • Slovene: lipa "linden" (singular) – lipi "linden" (dual) – lipe "linden" (plural)
  • Tamil "Aan","Pen" "Man,Woman , (Male,Female )" (Singular) – AanKal, Penkal "Two or more Man,Woman (Males, Females)
  • Sanskrit puruṣas "man" (singular) – puruṣau "two men" (dual) – puruṣās "men" (plural)
  • Swahili: mtoto "child" (singular) – watoto "children" (plural)
  • Ganda: omusajja "man" (singular) – abasajja "men" (plural)
  • Georgian: კაცი k'aci "man" (singular) – კაცები k'acebi "men" (where -i is the nominative case marker)
• Simulfixion (through various kinds of internal sound alternations):
  • Arabic: كِتَاب kitāb "book" (singular) – كُتُب kutub "books" (plural)
• Apophony (alternating between different vowels):
  • Welsh: bachgen "boy" – bechgyn "boys"
• Reduplication (through doubling):
  • Indonesian: orang "person" (singular) – orang-orang "people" (plural); BUT dua orang "two people" and banyak orang "many people" (reduplication is not done when the context is clear and when the plurality is not emphasized)
  • Somali: buug "book" (singular) – buug-ag "books" (plural)
• Tonality (by changing a drag tone to a push tone)
  • Limburgish: daãg "day" (singular) – daàg "days" (plural)

Elements marking number may appear on nouns and pronouns in dependent-marking languages or on verbs and adjectives in head-marking languages.

English (dependent-marking)	Western Apache (head-marking)
Paul is teaching the cowboy.	Paul idilohí yiłch’ígó’aah.
Paul is teaching the cowboys.	Paul idilohí yiłch’ídagó’aah.

In the English sentence above, the plural suffix -s is added to the noun cowboy. In the equivalent in Western Apache, a head-marking language, a plural infix da- is added to the verb yiłch’ígó’aah "he is teaching him", resulting in yiłch’ídagó’aah "he is teaching them" while noun idilohí "cowboy" is unmarked for number.

Number particles

Plurality is sometimes marked by a specialized number particle (or number word). This is frequent in Australian and Austronesian languages. An example from Tagalog is the word mga [mɐˈŋa]: compare bahay "house" with mga bahay "houses". In Kapampangan, certain nouns optionally denote plurality by secondary stress: ing laláki "man" and ing babái "woman" become ding láláki "men" and ding bábái "women".

Classifiers with number morphology

In Sanskrit and some other languages, number and case are fused category and there is concord for number between a noun and its predicator. Some languages however (for example, Assamese), lack this feature.

Languages that show number inflection for a large enough corpus of nouns and/or allow them to combine directly with singular and plural numerals can be described as non-classifier languages. On the other hand, there are languages that obligatorily require a counter word or the so-called classifier for all nouns. For example, the category of number in Assamese is fused with the category of classifier, which always carries a definite/indefinite reading. The singularity or plurality of the noun is determined by the addition of the classifier suffix either to the noun or to the numeral. Number system in Assamese is either realized as numeral or as nominal inflection, but not both. Numerals [ek] 'one' and [dui] 'two', can be realized as both free morpheme and clitics. When used with classifiers, these two numerals are cliticised to the classifiers.

Obligatoriness of number marking

In many languages, such as English, number is obligatorily expressed in every grammatical context. Some limit number expression to certain classes of nouns, such as animates or referentially prominent nouns (as with proximate forms in most Algonquian languages, opposed to referentially less prominent obviative forms). Still others, like Chinese and Japanese, number marking is not consistently applied to most nouns unless a distinction is needed or already present.

A very common situation is for plural number to not be marked if there is any other overt indication of number, as for example in Hungarian: virág "flower"; virágok "flowers"; hat virág "six flowers".

Transnumeral

Many languages, such as Chinese, Indonesian, Japanese and Malay, have optional number marking. In such cases, an unmarked noun is neither singular nor plural, but rather ambiguous as to number. This is called transnumeral or sometimes general number, abbreviated trn. Many such languages have optional number marking, which tends to be used for definite and highly animate referents, most notable first-person pronouns.

Inverse number

The languages of the Tanoan family have three numbers – singular, dual, and plural – and exhibit an unusual system of marking number, called inverse number (or number toggling). In this scheme, every countable noun has what might be called its "inherent" or "expected" numbers, and is unmarked for these. When a noun appears in an "inverse" (atypical) number, it is inflected to mark this. For example, in Jemez, where nouns take the ending -sh to denote an inverse number, there are four noun classes which inflect for number as follows:

class	description	singular	dual	plural
I	animate nouns	-	-sh	-sh
II	some inanimate nouns	-sh	-sh	-
III	other inanimate nouns	-	-sh	-
IV	mass (non-countable) nouns	(n/a)	(n/a)	(n/a)

As can be seen, class-I nouns are inherently singular, class-II nouns are inherently plural, class-III nouns are inherently singular or plural. Class-IV nouns cannot be counted and are never marked with -sh. (From Sprott 1992, p. 53.)

A similar system is seen in Kiowa (Kiowa is distantly related to Tanoan languages like Jemez):

class	singular	dual	plural
I	-	-	-ɡɔ
II	-ɡɔ	-	-
III	-ɡɔ	-	-ɡɔ
IV	(n/a)	(n/a)	(n/a)

(See also Taos language: Number inflection for a description of inverse number suffixes in another Tanoan language.)

Number agreement

Verbs

Main article: Grammatical conjugation

In many languages, verbs are conjugated according to number. Using French as an example, one says je vois (I see), but nous voyons (we see). The verb voir (to see) changes from vois in the first person singular to voyons in the plural. In everyday English, this often happens in the third person (she sees, they see), but not in other grammatical persons, except with the verb to be.

Adjectives and determiners

Adjectives often agree with the number of the noun they modify. For example, in French, one says un grand arbre [œ̃ ɡʁɑ̃t aʁbʁ] "a tall tree", but deux grands arbres [dø ɡʁɑ̃ zaʁbʁ] "two tall trees". The singular adjective grand becomes grands in the plural, unlike English "tall", which remains unchanged.

Other determiners may agree with number. In English, the demonstratives "this", "that" change to "these", "those" in the plural, and the indefinite article "a", "an" is either omitted or changes to "some". In French and German, the definite articles have gender distinctions in the singular but not the plural. In Spanish and Portuguese, both definite and indefinite articles are inflected for gender and number, e.g. Portuguese o, a "the" (singular, masc./fem.), os, as "the" (plural, masc./fem.); um, uma "a(n)" (singular, masc./fem.), uns, umas "some" (plural, masc./fem.)

In the Finnish sentence Yöt ovat pimeitä "Nights are dark", each word referring to the plural noun yöt "nights" ("night" = yö) is pluralized (night-PL is-PL dark-PL-partitive).

Exceptions

See also: Synesis and Plurale tantum

Sometimes, grammatical number will not represent the actual quantity. For example, in Ancient Greek neuter plurals took a singular verb. The plural form of a pronoun may also be applied to a single individual as a sign of importance, respect or generality, as in the pluralis majestatis, the T-V distinction, and the generic "you", found in many languages, or, in English, when using the singular "they" for gender-neutrality.

In Arabic, the plural of a non-human noun (one that refers to an animal or to an inanimate entity regardless of whether the noun is grammatically masculine or feminine in the singular) is treated as feminine singular—this is called the inanimate plural. For example:

رجل جميل (rajul jamīl) 'beautiful/handsome man': rajul (man) is masculine singular, so it takes the masculine singular adjective jamīl.

بيت جميل (bayt jamīl) 'beautiful house': bayt (house) is masculine singular, so it takes the masculine singular jamīl.

كلب جميل (kalb jamīl) 'beautiful dog':kalb (dog) is masculine singular, so it takes the masculine singular jamīl.

بنت جميلة (bint jamīlah) 'beautiful girl': bint is feminine singular, so it takes the feminine singular jamīlah.

سيارة جميلة (sayyārah jamīlah) 'beautiful car': sayyārah is feminine singular, so it takes the feminine singular jamīlah.

رجال جميلون (rijāl jamīlūn) 'beautiful/handsome men': rijāl (men) is masculine plural, so it takes the masculine plural jamīlūn.

بنات جميلات (banāt jamīlāt) 'beautiful girls': banāt is feminine plural, so it takes the feminine plural jamīlāt.

but

بيوت جميلة (buyūt jamīlah) 'beautiful houses': buyūt (houses) is non-human plural, and so takes the inanimate plural (feminine singular) jamīlah.

سيارات جميلة (sayyārāt jamīlah) 'beautiful cars': sayyārāt is non-human plural, and so takes the inanimate plural jamīlah.

كلاب جميلة (kilāb jamīlah) 'beautiful dogs': kilāb is non-human plural, and so takes the inanimate plural jamīlah.

Collective nouns

Main article: Collective noun

A collective noun is a word that designates a group of objects or beings regarded as a whole, such as "flock", "team", or "corporation". Although many languages treat collective nouns as singular, in others they may be interpreted as plural. In British English, phrases such as the committee are meeting are common (the so-called agreement in sensu "in meaning"; with the meaning of a noun, rather than with its form). The use of this type of construction varies with dialect and level of formality.

Semantic vs. grammatical number

All languages are able to specify the quantity of referents. They may do so by lexical means with words such as English a few, some, one, two, five hundred. However, not every language has a grammatical category of number. Grammatical number is expressed by morphological and/or syntactic means. That is, it is indicated by certain grammatical elements, such as through affixes or number words. Grammatical number may be thought of as the indication of semantic number through grammar.

Languages that express quantity only by lexical means lack a grammatical category of number. For instance, in Khmer, neither nouns nor verbs carry any grammatical information concerning number: such information can only be conveyed by lexical items such as khlah 'some', pii-bey 'a few', and so on.^[9]

Auxiliary languages

Auxiliary languages often have fairly simple systems of grammatical number. In one of the most common schemes (found, for example, in Interlingua and Ido), nouns and pronouns distinguish between singular and plural, but not other numbers, and adjectives and verbs do not display any number agreement. Note however that in Esperanto adjectives must agree in both number and case with the nouns that they qualify.

See also

• Count noun
• Elohim
• Generic antecedents
• Grammatical agreement
• Grammatical conjugation
• Grammatical person
• Inflection
• Measure word
• Names of numbers in English
• Noun class
• Number names
• Plurale tantum
• Romance plurals

Notes

1. ^ SIL Dictionary of Linguistic Terms: What is Number?
2. ^ Nicolas, David (2008). "Mass nouns and plural logic." Linguistics and Philosophy 31.2, pp. 211–244 http://d.a.nicolas.free.fr/Nicolas-Mass-nouns-and-plural-logic-Revised-2.pdf
3. ^ Greenberg, 1972.
4. ^ Occurrence of Nominal Plurality
5. ^ Lunt (1982, p. 204).
6. ^ http://en.wiktionary.org/wiki/quadral
7. ^ Gregersen, Edgar A., "Language in Africa", p. 62. (Note that Marshallese is not a language spoken in Africa.)
8. ^ Corbett, Greville G., "Number", pages 25–30, 40, 46, 224, 317, 358, Cambridge Textbooks in Linguistics, P240.8.C67 2000, ISBN 0 521 64016 4
9. ^ See, for example, the Linguistic sketch in Khmer article at UCLA Language Materials project.

Bibliography

• Beard, R. (1992) Number. In W. Bright (ed.) International Encyclopedia of Linguistics.
• Corbett, G. (2000). Number. Cambridge University Press.
• Greenberg, Joseph H. (1972) Numeral classifiers and substantival number: Problems in the genesis of a linguistic type. Working Papers on Language Universals (Stanford University) 9. 1-39.
• Laycock, Henry. (2005) 'Mass nouns, Count nouns and Non-count nouns' Encyclopedia of Language and Linguistics. Oxford: Elsevier.
• Laycock, Henry. (2006) Words without Objects. Oxford: Clarendon Press.
• Lunt, Horace G. (1982) Fundamentals of Russian. Revised edition (1968). Reprinted by Slavica Publishers, Columbus Ohio.
• Merrifield, William (1959). "Classification of Kiowa nouns". International Journal of American Linguistics 25 (4): 269–271. doi:10.1086/464544. 
• Mithun, Marianne (1999). The languages of native North America (pp. 81–82, 444-445). Cambridge University Press, ISBN 0-521-23228-7.
• Nicolas, David (2008). "Mass nouns and plural logic". Linguistics and Philosophy 31.2, pp. 211–244 http://d.a.nicolas.free.fr/Nicolas-Mass-nouns-and-plural-logic-Revised-2.pdf
• Sprott, Robert (1992). Jemez syntax. (Doctoral dissertation, University of Chicago, USA).
• Sten, Holgar (1949) Le nombre grammatical. (Travaux du Cercle Linguistique de Copenhague, 4.) Copenhagen: Munksgaard.
• Watkins, Laurel J.; & McKenzie, Parker. (1984). A grammar of Kiowa. Studies in the anthropology of North American Indians. Lincoln: University of Nebraska Press. ISBN 0-8032-4727-3.
• Weigel, William F. (1993). Morphosyntactic toggles. Papers from the 29th Regional Meeting of the Chicago Linguistic Society (Vol. 29, pp. 467–478). Chicago: Chicago Linguistic Society.
• Wiese, Heike (2003). Numbers, language, and the human mind. Cambridge University Press, ISBN 0-521-83182-2.
• Wonderly, William L.; Gibson, Lorna F.; Kirk, Paul L. (1954). "Number in Kiowa: Nouns, demonstratives, and adjectives". International Journal of American Linguistics 20: 1–7. doi:10.1086/464244. JSTOR 1263186. 
• Unicode's plural rules collection http://www.unicode.org/cldr/data/charts/supplemental/language_plural_rules.html
• "Cultural Constraints on Grammar and Cognition in Pirahã". http://www.sil.org/americas/brasil/publcns/anthro/PHGrCult.pdf.