We now turn from biological evolution to cultural evolution on a very fast time scale, looking at the emergence of Nicaraguan Sign Language in a mere thirty years or so. I will argue that this was possible only because and when the broader community provided deaf Nicaraguans with social structures and knowledge of the idea of language.
Home Sign
Deaf babies exposed to a sign language (a full human language based on manual and facial gestures rather than speech) from birth follow a similar timetable of linguistic development to that of hearing children acquiring spoken language. Lacking a sign language, families in which a deaf child is raised by non-signing parents instead develop home sign, a rudimentary form of communication between the deaf child and other family members which comprises a small “vocabulary” of manual gestures (“signs”) together with a few strategies for combining signs into longer messages (
Goldin-Meadow, 2003;
Goldin-Meadow & Feldman, 1975).
I want to stress that home sign is the product of a community (albeit a very small one). It is often suggested that the deaf child develops home sign; but I emphasize that is the product of the collective efforts of the family to communicate. Clearly, home sign does not rest on direct input from either a spoken language or a sign language since these are children of speaking parents who do not know sign language. But there is indirect input: The child sees gestures – both deictic gestures and more descriptive gestures – used by other family members as part of speech acts. These family members show the child that pointing and pantomime can be used to communicate and the child’s caregiver will provide a structured environment such as pointing at pictures in picture books. The “indirect input” from speech is even less direct. The child sees family members take turns to speak and gesture, sometimes to no apparent end, but in other cases with clear links to emotional impact or achieving instrumental goals. All this creates for the child an understanding of the general notion of dialogue conducted by a blend of gesture and facial expression
Nicaraguan Sign Language (NSL): A New Sign Language
Before the 1980s, deaf Nicaraguans had little contact with each other. Children developed idiosyncratic home sign within their families but no sign language emerged. However, a vocational school for the deaf opened in 1981 in Managua. Instruction was conducted in Spanish, with minimal success but the children began to develop a new, gestural system for communicating with each other – in part by consolidating the different home signs each had developed. The gestures soon expanded to form a rudimentary sign language. By 1986 the early collection of gestures developed into an expressive sign language, Nicaraguan Sign Language (NSL), which is still in a state of flux, as the sign-lexicon and constructions keep changing.
Here is one study of such change (
Senghas, Kita, & Özyürek, 2004) – (see
Russo & Volterra, 2005;
Senghas, Özyürek, & Kita, 2005 for a commentary and response) – comparing the performance of the first, second and third cohorts (Deaf Nicaraguans who acquired NSL in the first, second or third 10 years of its existence). Subjects were asked to use their hands to describe a segment of a Tweety Bird and Sylvester cartoon in which Sylvester, having swallowed a bowling ball, “rolls” down the hill. Manner (rolling) and path (downward) are expressed simultaneously in the co-speech gesture of Spanish speakers as well as in the signs of many by early cohort NSL signers. By contrast, third-cohort NSL signers tend to express manner and path sequentially, first signing “rolling” and then “downward”. In other words, gestures seen rarely in early cohorts become entrenched as accepted signs of NSL by the third cohort.
We thus see that NSL is not a copying of Spanish co-speech gestures. This separation of manner and path is a novel conventionalization – though it must be noted that many sign languages do express manner and path simultaneously – NSL is developing its own signs, not simply copying other sign languages.
Recall from the last section that observation of a commonality between two communicative structures could yield the isolation of that commonality as a gesture or vocalization betokening some shared aspect of the event, object or action denoted by each of the two structures. We also saw that such “semantic fractionation” might lead in time to the emergence of a construction for “putting the pieces back together”, with the pieces becoming instances of a widening class of slot fillers.
If manner and path are expressed separately, it may no longer be clear that the two aspects of movement occurred within a single event.
Roll followed by
downward might mean “rolling, then descending”.
Senghas et al. (2004) show that NSL developed a way to put the pieces back together: NSL now has the X-Y-X construction, such as
roll-descend-roll, to express simultaneity. This string can serve as a structural unit within a larger expression like
cat [roll descend roll], or it can even be nested, as in
waddle [roll descend roll] waddle. This construction never appeared in the gestures of the Spanish speakers and is also quite unlike any construction of spoken Spanish
Creating A Community
My hypothesis is that NSL differs from home sign because the existence of a community provides more opportunities to use signs and choose signs, so that although some get lost to the community, increasingly many gain power by being widely shared. An “engine” for this process is provided by the fact that, since knowledge of another language is possessed by some members of the community, they seek to translate this knowledge into the new medium (as is proven for the lexicon), and some of these attempts to capture a given property will become widespread.
Some have claimed that NSL arose “from scratch”, suggesting that the community of deaf Nicaraguans who developed it lacked exposure to a developed language. But did deaf Nicaraguans “reinvent Language” or “invent a language”? I argue for the latter case and outline how knowledge of other languages may have complemented the language-readiness of the brain in the development of NSL (
Arbib, 2009). The foundational document for this analysis is Laura Polich’s book analyzing the changing social matrix that supported the emergence of NSL,
The Emergence of the Nicaraguan Deaf Community in Nicaragua: “With Sign Language You Can Learn So Much” (
Polich, 2005). We have seen that there was no evidence of sign language in use in Nicaragua in 1975 and that the turning point came when a vocational school was established that kept adolescents and young adults together “at a time when they were carving out their identities and craving a peer group in which to try out and enact their abilities to be social actors” (Polich, p.146). Note this key emphasis on the concepts of s
ocial actor, peer group and
creating one’s identity which complement our earlier emphasis on brain mechanisms.
Polich charts the transition from a deaf person in Nicaragua having no peer group and thus having the passive social role of an outcast to a Deaf person who has a language which empowered him/her to be a true social actor within the Deaf community created by the enriched communication that came with the expanding capabilities of NSL Note that NSL did not develop in a vacuum, nor simply as a resulting of children pooling what their individual versions of home sign. Teachers played an important role in developing a community which provided social opportunities for the deaf children, going beyond the classroom. Ruthy Doran, a hearing person who taught the deaf children at the vocational school and also did much to create a social environment for them, told Polich:
There wasn't a sign language [around 1980] … But we were able to understand one another. We would … use a lot of the gestures that everyone around here (in Nicaragua) uses and we had a set of some signs that the students made up. (They aren't used now.) We had special signs like for the days of the week that we had used with each other for years, and they had learned new signs … which they taught me. And when everything else failed, we would write words down, or else act it out.
Thus, in its early stages the community being formed included hearing people who spoke Spanish, while even those who could not speak had at least a small vocabulary of written Spanish. The talk of community must not blind us to the fact that each aspect of the language had to meet two conditions:
- a specific individual or dyad used it for the first time (or the first time that they and others knew about) and
- others, understanding its meaning, came to use it themselves.
It is true that “In the early 1980s, many deaf Nicaraguans knew no grammar,” but false that “In the early 1980s, no deaf Nicaraguans knew grammar.” The impressive achievement of creating this new language, NSL, did not have to rest solely on innate capabilities of the human brain (which distinguish us from other primates, for example) but could indeed exploit the cultural innovations of existing language communities. Both individuals and institutions played a crucial role in the emergence of NSL and the Nicaraguan Dead community (the capital “D” in deaf indicates that this was not simply a group of deaf people but a group united by the sharing of a sign language).
Many early members of the Deaf Association which emerged to support the development of this community credit Javier Gómez López with teaching all the others the version of NSL of that time. As Polich documents, his interest in sign language began in the late 1970s when he was given a sign language dictionary during an athletic trip to Costa Rica. He was dedicated to making sign language a functional communication system for himself and his friends, and to sharing this knowledge with other deaf Nicaraguans. He would seek out anyone who knew sign language or had access to a dictionary to improve his vocabulary, and would simultaneously teach what he learned to the others. Moreover, Javier was active in the workshops around 1990 in which Association members met in small groups to discuss which variations of signs should be adopted as “standard”. Indeed, the second cohort of NSL signers did far more than spontaneously create new signs in isolation – they studied both Spanish dictionaries and ASL (American Sign Language) videos as a basis for devising new signs to expand NSL.
In 1991, the Royal Swedish Deaf Association began to finance the collection of entries for a professionally published sign language dictionary, eventually published in March 1997. But the Swedes did not teach Swedish Sign Language. Rather, they helped the Nicaraguans systematize what they had achieved in the early stages of creating NSL, and provided models of expressiveness of sign language which would have spurred the development of new modes of expression in NSL. Moreover, they provided a model for becoming first-rate members of a Deaf community rather than second-rate members of an oral society – though, alas, the job-market for the deaf in Nicaragua remains sorely restricted.
What Took Us So Long?
It has been argued that the brain of
Homo sapiens was biologically ready for language perhaps 200,000 years ago but, if increased complexity of artifacts like art and burial customs correlate with language of some subtlety, then human languages as we know them arose at most 50,000 to 90,000 years ago (
Noble & Davidson, 1996). But if we accept the idea that it took humans with modern-like brains 100,000 years or more to invent language-as-we-know-it, we must ask what advantage the NSL community had that early humans lacked.
I have suggested that NSL differs from home sign because (i) the existence of a community provides more opportunities to use signs and choose signs, so that some get lost to the community while increasingly many gain power by being widely shared; and (ii) that, since knowledge of another language is possessed by some members of the community, they seek to translate this knowledge into the new medium.
Early humans would share (i) but not (ii) with the deaf Nicaraguans.
The very idea of language can have a catalytic effect. It seems almost inconceivable that the very idea of language had to be invented, but we know that writing was only invented some 5,000 years ago. We believe that no genetically based changes in the Homo sapiens brain were required to support literacy, but we have seen that literacy can change the brain as it develops. Moreover, many societies have lasted till modern times with no written form for their spoken language.
Yet, once one has the idea of writing, it is a straightforward exercise to invent a writing system. Around 1820, Sequoyah, a Cherokee who knew very little English and was illiterate invented a Cherokee syllabary, with 86 characters to represent the sounds of the Cherokee language, inspired solely by the idea of writing (
Walker & Sarbaugh, 1993).
We can conclude, then, by summarizing the
extended Mirror System Hypothesis as involving the following evolutionary innovations:
- A Mirror system for grasping: Mirror neurons can be recruited to recognize and encode an expanding set of novel actions. This stage is subdivided into (a) Providing feedback for dexterous manual control; and (b) Acting with other brain regions to make useful information available for interacting with others
- Simple imitation followed by Complex imitation.
- Protosign: emerging as the ability to engage in pantomime evolves into the ability to make conventional gestures to disambiguate or supplant pantomime.
- Proto-speech: Early protosign provided the scaffolding for early protospeech after which both developed in an expanding spiral till protospeech became dominant.
I have suggested that this sufficed for the emergence of the language-ready brain, but that the emergence of “full-blown language” with syntax and compositional semantics was “post-biological”. The discussion of the emergence of NSL suggests how such cultural evolution was as much devoted to the discovery of ideas of what language could do as it was to the discovery of particular grammatical rules and constructions. Indeed, once these ideas are available to a community, then the invention of novel lexical items and constructions can occur on a timescale of decades rather than millennia.
The publisher's final edited version of this article is available at