New Sign Languages and Language Evolution

#Word count limit: 2,500 words, counting the abstract and text only, and 15-18 references#

Penultimate draft (3500 words):

Arbib, M.A., 2007, New Sign Languages and Language Evolution, Current Directions in Psychological Science (to appear).

New Sign Languages and Language Evolution

Michael A. Arbib

Computer Science Department, Neuroscience Program, and USC Brain Project

University of Southern California

Los Angeles, CA 90089-2520

Abstract

Human language is far more than speech and its derivatives such as writing. Human signed languages like American Sign Language are fully expressive human languages, and speakers normally accompany their speech with facial and manual gestures. Thus any theory of language evolution must address these integral roles that manual signs and gestures play today. What are the capabilities of the human brain that make it possible for humans to learn language while other creatures can not? How much structure must the social environment offer a child to acquire language? We probe these questions by studying two sign languages of recent vintage. Nicaraguan Sign Language developed in just 25years while Al-Sayyid Bedouin Sign Language developed over at most 70 years, and are still developing. We examine the emergence and dynamics of these languages to advance discussion of what supports society offered to allow these communities to exploit the human brain’s readiness for language in novel ways.

Design Features and Language Evolution

(Hockett, 1987) listed "designfeatures" common to all languages. Every language consistsof discrete units which can be combined in open-ended ways to express novel meanings – yielding discreteness and combinatorial patterning, respectively. Duality of patterning refers to the way in which meaningful units are composed from a smaller set of meaningless units as when discrete sounds combine to form words. Moreover, many Deaf people communicate by grammatically combining signs, based on hand shape and trajectory, possibly accompanied by expressive facial movements. Their sign languages are fully expressive human languages yet share certain features which distinguish them from spoken language, due to the modality of transmission (Sandler & Lillo-Martin, 2006). Nonetheless, (Stokoe, 1960) demonstrated that American Sign Language (ASL) also has duality of patterning – meaningless handshapes, locations, and movements combine to form a large set of signs.

However, something called a design feature of language may actually reflect more general capabilities. For example, a frog’s behavior exhibits discreteness and combinatorial patterning, being composed from discrete motor schemas like orient, jump, lunge, and snap. The Mirror System Hypothesis (Arbib, 2005; Rizzolatti & Arbib, 1998) suggests that much of what enables the human brain to supportlanguage rests on mechanisms which evolved to support praxis and protolanguage rather than language per se: Praxis comprises skills that include manipulation of objects towards some practical end; whereas protolanguage is a form of communication posited to be used by communities of our distant ancestors who – transcending the limited vocalizations and gestures of nonhuman primates – shared a stock of communicative symbols (call them protowords) which could be added to repeatedly, but has no syntax. Here we leave implicit the role of the mirror system and instead present hypothesized evolutionary stages that start with the capacity for imitation.

Apes have a capacity for simple imitation. Gorillas learn elaborate feeding strategies but may take months to do so. (Byrne, 2003) implicates imitation by behavior parsing. The young ape comes to recognize relevant subgoals and by trial and error derives action strategies for achieving them. By contrast, humans are capable of complex imitation, perceiving when and how a novel action may be approximated by a composite of known actions and employing this perception to perform an approximation to the observed action, which may then be refined through practice. This grounds the claim for two evolutionary stages:

A simple imitation system for grasping, shared with the common ancestor of human and apes.

A complex imitation system for grasping, unique to the hominim line leading from that common ancestor to humans.

Each of these changes would have been of evolutionary advantage in supporting the transfer of novel skills between the members of a community. But what of communication? Monkey vocalizations are innately specified (though occasions for using a call may change with experience), whereas a group of apes may communicate with novel gestures, perhaps acquired by ontogenetic ritualization whereby some fragment of an action comes to serve for communication about that action (Tomasello, Call et al., 1997). This supports the argument for two further stages of hominim evolution yielding:

Protosign: a manual-based communication system breaking through the fixed repertoire of primate vocalizations to yield an open repertoire.

Protolanguage: an expanding spiral of conventionalized manual, facial and vocal communicative gestures.

The transition from complex imitation to protosign may have involved pantomime first of manual praxic actionsandthen of non-manual actions (e.g., flapping the arms to mime a flying bird). Further evolution would yield protosign as a system of conventional gestures that initially simplify, disambiguate (e.g., to distinguish "bird" from "flying") or extend pantomime but in due course come to replace it (Arbib, 2005). This capability for protosign may then have provided essential scaffolding for protospeech and the human language-ready brain. Finally we have:

The transition from protolanguage to language: the development of syntax and compositional semantics

One influential view is that (i) each human is innately endowed with a Universal Grammar for an autonomous syntax that combines words into well-formed sentences irrespective of their meaning; and (ii) that the child need simply hear a few sentences to “set the parameter” – such as whether or not the language is S-O-V (having sentences based on the form Subject-Verb-Object) – for each key principle to acquire the grammar of her first language (Baker, 2001).

There is no space to develop my counter-argument (Arbib, 2005) here in any detail, but the key hypothesis is this: Once humans have brains that support both complex imitation and protolanguage (combining speech and gesture), they have brains that can learn and use language. Complex imitation combines the ability to perceive that a novel action may be approximated by a composite of known actions associated with appropriate subgoals with the ability to employ this perception to perform an approximation to the observed action, which may then be refined through practice. Both parts come into play when the child is learning a language; while the former predominates in adult use of language. However, a modern language combines a vast lexicon with a large number of constructions which determine how words and morphemes may be combined to create new meaning. The catch, then, is that it may well have taken early Homo sapiens many tens of millennia to develop enough lexemes and constructions for a tribe’s communication system to qualify as a language rather than a protolanguage (though no rigid threshold is claimed).

But were tens of millennia really necessary? We now turn to two new sign languages which appeared in tens of years rather than tens of millennia to see if there is something about the environment in which they emerged which short circuited the historical path to language.

Two New Sign Languages

A deaf child may reach six years of age with less than 10 words of oral vocabulary, yet deaf babies raised among signers follow the same linguistic milestones as a hearing child acquiring a spoken language. A deaf child raised apart from deaf signers will often develop home sign, an idiosyncratic set of gestures (some pantomime-like, others more conventionalized) usedto communicate with family members. Typically, such a child will have a small “vocabulary” of home signs together with a few strategies for combining signs into longer messages (Goldin-Meadow, 2003).

Before the 1970s, deaf Nicaraguans had littlecontact with each other and no shared sign language emerged. An elementary school for special education of the deaf was opened in Managua, Nicaragua in 1977, followed bya vocational school in 1981. Students continued their contactoutside school hours, and by the mid-1980s deaf adolescentswere meeting regularly on weekends. They began to develop a new gestural system, in part by consolidating their idiosyncratic home signs, which soon expanded to form a rudimentarysign language (Kegl, 1994) from which emerged Nicaraguan Sign Language (NSL). As of 2005, there were about 800 deaf signers of NSL, ranging from 4 to 45 years old.

Al-Sayyid Bedouin Sign Language (ABSL) is another recent sign language which, unlike NSL, developed within the family structures of a pre-existing socially stable community. The Al-Sayyid Bedouin group is in the Negev region of Israel, but ABSL is distinct from Israeli Sign Language. The group descends from a single founder, who arrived from Egypt 200 years ago. About 150 people with congenital deafness have been born into the community within the past three generations. Not only the deaf members of the community but also many of its hearing members communicate by means of ABSL. Signers readily use ABSL to converse about topics as diverse as social security benefits, construction techniques, and fertility (Sandler, Meir et al., 2005).

And there is no reason to believe that either of these sign languages has finished developing. Clearly, the signs employed in each language are different from spoken words. However, not only are the signs different, so too are the constructions which combine them. Both NSL and ABSL employ constructions different from those of the circumambient Spanish and Arabic, respectively. Here are examples:

Motion Description in Nicaraguan Sign Language

(Senghas, Kita et al., 2004) grouped 30 deaf Nicaraguans into cohorts based on when they were first exposed to NSL. Signedexpressions were recorded while subjects described a video clip in which the cat Sylvester, having swallowed a bowling ball, wobbles rapidly down a steep street. These were compared to co-speech gestures (the hand movements which normally, and usually unconsciously accompany speech) produced by 10 hearingNicaraguans describing the event in Spanish. This event combines manner (rolling) and path (descending). Senghas et al. found that all the Spanish speakers' gestures and 73% of thefirst-cohort’s expressions included manner and path simultaneously.By contrast, less than a third of these expressionsfor the younger, second- and third-cohort, signers wereof this kind – evidence of an emergent feature of NSL which made the segmented, sequenced construction their preferred (but not exclusive)means of expressing motion events. Moreover, NSL now has the X-Y-X construction, not seen in the gestures or speech ofSpanish speakers, to express simultaneity of X and Y.

Word Order in Al-Sayyid Bedouin Sign Language

Sandler et al. (2005) studied eight signers of the second generation of ABSL signers when spontaneously recounting a personal experience or describing single events portrayed in video clips In the vast majority of sentences recorded, the grammatical relation between subject (S), object (O), and verb (V) was given by the order
S-O-V, though subject or object could be omitted. For example, in the description WOMAN APPLE GIVE; MAN GIVE [‘‘The woman gave an apple; (she) gave (it) to the man’’], the first clause is S-O-V, and the second clause is IO(indirect object)-V. The only hearing subject they studied, bilingual in Arabic and ABSL, shows no influence of the local Arabic’s S-V-O order in his signing. Hence, the robust word-order pattern exhibited by the data demonstrates an independent development within ABSL.

Emergence of the Nicaraguan Deaf Community

Is the implication of the rapid rise of ABSL and NSL that once the brain of Homo sapiens achieved its present form, a mere 2 or 3 generations sufficed for emergence of a full human language? To the contrary, both ABSL and NSL owe their rapid development to the existence of social matrices that would not have been present “in the beginning”. I believe that the researchers involved with ABSL and NSL would agree, though some of the popular press discussing their work has made suggestions to the contrary. A detailed history by (Polich, 2005) may help us see not only the social forces at work in the emergence of NSL, but also the crucial role of individuals. She emphasizes that the increased opportunities for adolescents and young adults to get together, which distinguished the 1980s from the 1950s, played a vital role in forming the Nicaraguan Deaf community and NSL. Ruthy Doran, a teacher who, starting around 1980, gave deaf adolescents regular opportunities to socialize with each other, told Polich: “There wasn't a sign language at the time ... But we were able to understand one another. We would … use a lot of the gestures … And when everything else failed, we would write words down, or else act it out.” Thus the community being formed included hearing people who spoke Spanish, while some who could not speak had at least some words of written Spanish.

Ad hoc use of signs differs greatly from using grammar to flexibly create new sentences, but the creation of NSL did exploit prior innovations of other language communities. News of existing sign languages reached Nicaragua in the late 1970s (Polich, 2005). It was a revelation to see that signs could constitute a full, expressive language. Alas, teachers were unable to get approval to use Costa Rican sign language for instruction in Managua. However, the idea of sign language was now available to some members of the nascent community. Polich also records the formation in the late 1980s of the Nicaraguan Association to Help and Integrate the Deaf. The early officers were deaf young adults who could speak Spanish but were also part of the community that was creating NSL. Polich helps us see individuals as embedded within a developing community in which increasing social interaction supported the growth of NSL while the increasing “bandwidth” of communication in NSL strengthened the community and increased the participation of those who could not speak Spanish.

Early members of the Deaf Association told Polich that one individual, Javier Gómez López, "taught" all the others the sign language (in its early form). He had been given a sign language dictionary during an athletic trip to Costa Rica in the late 1970s. He became dedicated to making sign language a functional communication system for himself and his friends, and to sharing this knowledge with other deaf persons in Nicaragua. He was active in workshops which decided which variations of signs should be adopted as "standard". The Royal Swedish Deaf Association provided funds for officers of the Deaf Association to travel to other Central American countries for regional meetings of deaf people. The Swedes also financed the collection of entries for a professionally published dictionary for NSL, professional sign language instruction for teachers, and basic literacy training for the deaf.

Thus, although families play no role in transmission of NSL, the schools and Deaf Association has been essential in building the Nicaraguan Deaf community, fostering and transmitting NSL in a community setting. By contrast, the development of ABSL benefited from family and community structures very different from those in Nicaragua.

Broader Implications

ABSL shows the influence of socio-cultural traditions of the larger society on such things as the signs chosen to represent religious holidays – for example, the sign for MONTH derives from MOON and one sign for Thursday is MARKET because Thursday is market day. Yet, in constructions like S-O-V, the cultural development of the structure of ABSL seems to be internal to the sign language, and not influenced by the dialect of Arabic that is the language of the larger community. However, I shall suggest that it is crucial to distinguish the transfer of ideas about what to communicate and general properties of language that aid such communication from the specific forms adopted by the language.

(Wray, 1998) argued that an important mechanism in language evolution was fractionation, replacing the protowords of early protolanguages by words denoting their “components”. As protowords fractionated, syntactic constructions emerged to recapture the meanings of protowords – but then also supported new combinations and provided space for the creation of new words<Arbib, 2005 #3849>. I argue that this mechanism is at work in NSL. Senghas et al. (2004) observed such a two-fold scenario in the decomposition of path and manner, and the development of the X-Y-X construction to retrieve the simultaneity of the original gesture. My hypothesis is that the key capacity here is complex imitation, rather than a design feature specific to language, and certainly not a setting of parameters in some innate Universal Grammar.

Once one has the idea of pantomime, inventing new pantomimes is easy; and once one has complex imitation, the sharing of successful pantomimes and their ensuing conventionalization is also straightforward.