The Origins of Alternate Sign Languages in Australia: could they include hearing Impairment?

*    $ % Z # # # ` Z } = ~ `! ; Z ` number of communities scattered around the world where the sign language of the deaf is also routinely used by hearing individuals. Such communities are, without exception, culturally or geographically isolated (often practising endogamy) and have a high proportion of profoundly deaf members. The deaf group develops its own sign language and the hearing members acquire mastery of it to varying degrees, using it in particular to communicate with deaf friends and relatives.


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;OLZL HYL VY ^LYL MV\UK PU H number of communities scattered around the world where the sign language of the deaf is also routinely used by hearing individuals. Such communities are, without exception, culturally or geographically isolated (often practising endogamy) and have a high proportion of profoundly deaf members. The deaf group develops its own sign language and the hearing members acquire mastery of it to varying degrees, using it in particular to communicate with deaf friends and relatives.
Australia appears to be unique, however, in that almost every indigenous community may have had an alternate sign language. This was understood by all the population and used by the majority -a situation which is maintained in some communities to this day. This population, while living in relatively self-contained groups for most of the year, has strong cultural connections over large areas and largely exogamous marriage practices. Factors commonly cited as contributing to the development and maintenance of these systems are both cultural (including ceremonial speech taboos -especially by women in mourning and by young males undergoing initiation -and avoidance behaviour within certain kinship relations) and practical (communicating over distance, while hunting, or with others -the profoundly deaf or the monolingual outsider -who cannot understand spoken language). But Kendon (1988) points out "some use of signing has been recorded from many parts of Australia, including areas where extended speech taboos have not been reported" and Kwek (1991) writes "In this particular case [Punmu, Western Australia], it is hard to imagine a set of circumstances that would proscribe normal speech use to the extent of leading to the development of what appears to be a relatively complex sign system." The proportion of the indigenous population with severe to profound deafness is somewhat higher than in the mainstream population, but a much higher proportion has a mild-to-moderate conductive hearing loss. In Australia the prevalence of severe hearing loss (60-90 dB) in males aged 15-50 in the general population is around 1.0%, whilst the prevalence of mild-to-moderate loss (20-60 dB) is around 6.7% (Access Economics, 2006). A recent study of 134 Northern Territory (NT) Aboriginal prison inmates (Vanderpoll & Howard, 2012) found that 9.7% of that population had a severe hearing loss (65-90 dB), whereas 85% had a mild-to-moderate loss (25-65 dB). This widespread hearing loss has been largely ignored as a potential factor in the development of Australian indigenous signing.

The Uniqueness of Australian Indigenous Sign Languages
If we look at instances of hearing people using sign in communities across the world, a pattern emerges. Undoubtedly, one of the best known of such communities was Martha's Vineyard in the United States (Grace, 1985), where in the 1880 census the frequency of deafness was as high as 1 in 155 (compared to a national average of 1 in almost 6000). In the Chilmark town of Squibnocket the incidence was as high as 1 in 4 and incomers were obliged to learn the sign SHUN\HNL PU  (Nonaka, 2004(Nonaka, , 2012. Inuit Sign Language is used by both the deaf (about 50 people) and some of the hearing (about 100 people) in Inuit communities in the Canadian Arctic. In this area the incidence of hereditary deafness is reported to be up to six times that in southern Canada (Schuit, 2012 Green, 2009). Thus, unlike primary sign languages, Australian sign languages mirror the spoken form to a large extent and may be used in conjunction with it.
There are a number of obvious and oft-quoted situations in traditional Aboriginal society where sign language predominates. The best known of these is ceremonial speech taboo, of which the two main examples are restrictions imposed on widows and female kin in mourning and on young men undergoing initiation. It has also often been observed that signing is commonly used out bush, either as a means of silent communication when hunting, or to complement spoken language between people who are a great distance apart. However, the use of sign in many communities is much more pervasive and much more subtle than these observations would suggest. Kendon (1991) remarks that "although speech taboos may account for the complexity of signing in some areas, this must be understood as but a special elaboration within the context of a more general predisposition to use sign that seems to be widespread in Aboriginal society." (p.144) And, according to Green, Woods & Foley (2011), in central Australian communities, "Even in situations where it could be argued that sign is redundant to accompanying speech, it is nevertheless omnipresent. Sign is used in everyday conversation for particular cultural and pragmatic reasons, and a switch to sign may signal the circumspection required of certain topics". (p.68) Thus, in these communities anyone may use sign either to complement spoken communication or to replace it when it is socially inappropriate. Naturally, for some hearing impaired individuals in these communities sign is the primary mode of communication. For hearing individuals, sign may be used simply in place of greetings or small talk between friends, but may also be used  Kendon's (1988) conclusion is that, while the origins of Aboriginal sign languages may be unclear, the cultural environment of Aboriginal society has facilitated their development and retention: "if people, for whatever reason, resort to signs as a means of communication, if the society they live in conducts interaction in the [Aboriginal] way…the practice of using signs will be favoured, and may spread" This suggests that Aboriginal culture was already predisposed to accommodate the use of signing and that all that was needed was some kind of trigger to initiate its development. The question then is: what might that trigger have been? Over a period of years, Linnett Sánchez and colleagues measured the hearing of more than 900 children in the Anangu Pitjantjatjara-Yankuntjatjara (APY) Lands of north-western South Australia (Sánchez et al 2010). Using pure tone audiometry at four frequencies, they found that at a pure tone average threshold of 25 dBHL, 61% of children failed in one or both ears. The mean PTA (pure-tone audiometry) in "failing ears" was 29.6 dBHL. More recently Stoakes, Butcher, Fletcher & Tabain (2011) tested a much smaller group of children (n = 74) at Galiwin'ku on Elcho Island in the Northern Territory, using 6 pure tone frequencies. At a pure tone average threshold of 25 dBHL, 70% of children failed in one or both ears, with a mean PTA in "failing ears" of 35.0 dBHL. The results of these two studies are compared in Figure 1.  Stoakes, Butcher, Fletcher & Tabain, 2011 In the course of the NT Emergency Response (aka "The Intervention") from July 2007 to June 2012 over 10,000 children in the Northern Territory were given an "initial health check" and over half of these then received an audiology or ENT (ears, nose and throat) service. Of the latter group, 66.7% were found to have at least one type of middle ear condition and 51.4% had a hearing loss of more than 16 dB (Australian Institute of Health and Welfare, 2012).  (Stenton, 2003). There is also the possibility of alteration to the temporal properties of synapses and spikes in the & Sanes, 2007). Clearly mild-to-moderate hearing loss is very widespread in the Aboriginal population, but has it been present for long enough to have been a causal factor in the rise of Aboriginal sign languages?

Evidence for the antiquity of otitis media in Australia
Written and oral accounts  Levitt (1981, p. 54, pp. 143-44, plate 91) comments that on Groote Eylandt "infected ears were common". So common were they in fact that all over Australia various traditional remedies and healing methods evolved. In the Western Desert, for example, "they would pour breast milk into sore ears. Then maggots and pus would come out." (Glass & Hackett, 2003, p. 316). Often the local healer would be called upon: Dobson (2007, p 18) recalls "When I was a child with those very bad ears, deaf as a doornail, the pus and muck running out of my ears, old mame-mame Penangke would help heal them".
It seems clear from these accounts that chronic suppurative otitis media has been a part of life in Aboriginal Australia for at least the past two-and-a-quarter centuries. Evidence for its presence in the population before this is, however, somewhat scant and indirect. In about 25% of cases, this leads to erosion or absorption of the ossicles of the middle ear -particularly the incus. Evidence of such damage in medieval Danish skeletons has been reported by Qvist & Grøntved (2001). In other cases the mastoid bone in Native American skeletons has been found to be eroded by chronic infection (Gregg & Gregg 1987). Cholesteatomata may also erode through the roof of the middle ear (intracranially), leading to meningitis and brain abscesses (Mann 1992). However, no evidence of such pathology has been reported in Aboriginal skeletons.
A second possible indication is changes in mastoid air cell patterns. The mastoid portion of the temporal bone is diploic (semi-solid) until just before birth and only becomes pneumatised (porous) by subsequent ingrowth of the mucous membrane from the middle ear. The air cell system is usually developed by 4-5 years of age, but pneumatisation continues until the teens. Chronic otitis media is known to inhibit this process. Thus Gregg & Gregg (1987) suggest the degree and pattern of pneumatisation visible on mastoid radiographs of Native American skulls not only provide evidence of the presence of otitis media, but also give a rough indication as to [

Finally, aural exostoses are sessile (broad based) bony projections in the inner portion of the L_[LYUHS H\KP[VY` JHUHS ;OLZL HYL JH\ZLK I` [OL YL[LU[PVU VM Å\PK PU [OPZ HYLH TVZ[ JVTTVUS` [OYV\NO MHPS\YL [V KY` [OL LHYZ HM[LY Z^PTTPUN VY Z\YÄUN /V^L]LY [OLYL PZ HSZV [OL WVZZPIPSP[` [OL` TH` IL JH\ZLK I` [YHUZ\KH[PVU ZLLWPUN VM Å\PK MYVT HU PUMLJ[LK TPKKSL LHY 9VJOL
(1964) states "The etiology of aural exostoses has not been established with certainty. Some, but not all, develop in association with chronic suppurative otitis media". He examined 476 skulls of deceased Aboriginal people obtained from the Murray Black collection. Whilst it is probable that many of these were over 10,000 years old, it was not possible to determine which examples were pre-European contact and which were post-contact. Roche found that 28% of skulls had aural exostoses and concluded "The incidence of exostoses in these Australian aboriginal skulls is the highest that has been reported for any group except the American Indian skulls excavated in Kentucky".
It is, of course, no longer considered culturally appropriate for such examinations to be carried out. Thus it is unlikely further paleopathological evidence concerning the antiquity of otitis media in Aboriginal Australians will be forthcoming. (Kowal & Anderson, 2012  On the other hand, a more recent study by Pugach et al (2013) has revived the idea of multiple migrations. In an analysis of large-scale genotyping data, they found "an ancient association between Australia, New Guinea, and the Mamanwa (a Negrito group from the Philippines), with divergence times for these groups estimated at 36,000 years ago, … supporting the view that these populations represent the descendants of an early "southern route" migration out VM (MYPJH¹ I\[ [OL` HSZV KL[LJ[LK PUKPJH[PVUZ VM ¸Z\IZ[HU[PHS NLUL ÅV^ IL[^LLU [OL 0UKPHU populations and Australia" estimated to have occurred some 4,000 years ago. In this connection, it is interesting to note the prevalence of chronic otitis media in southern India is second only to that found in Aboriginal Australians (Acuin 2004). To quote McEvoy et al (2010) once more, "A broader survey of Australia, including diverse geographic sample populations, will be required to fully appreciate the continent's unique population history and consequent genetic heritage, as well as the importance of both to the understanding of health issues."  The possibility of a connection

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The most common reason (usually the only one) for the development of a sign language is hearing impairment in the population in question. The sign language situation in Australia is unique in that (1) sign languages probably developed amongst the entire population of the continent and (2) these sign languages were all of the alternate type -i.e. evolved to complement spoken language rather than replace it. But the Australian Aboriginal population is also unique in that it currently has the highest prevalence of otitis media and mild-to-moderate hearing loss in the world. If this is the result of a genetically determined susceptibility, then it may be of JVUZPKLYHISL One possible scenario is that this situation already existed more than 4,000 years ago in southern India and that a section of the population migrated to Australia, bringing with them their dogs, their susceptibility to otitis media, their phonologies, and their alternate sign languages.
In terms of investigating these possibilities further, one promising avenue would be to extend the search for otitis media susceptibility genes to the Aboriginal population.