(A travelogue of deafness, genetics and village sign languages for NZ Sign Language Week 2014)
Island paradises are wonderful, but after a few days I find usually myself restless. Exploring a place suits me more than lying on a beach.
Seemingly a lifetime ago now I visited the popular Indonesia holiday destination Bali not to lie about on a beachchair or try the nightlife, but to meet the deaf people of the small village Bengkala or, as they say in Indonesia, Desa Bengkala.
I’d learnt of the place obliquely, stumbling upon it while reading scientific papers.
Browsing a journal I rarely read—and whose title I’ve long forgotten—I encountered a striking summary for a research paper.
It read more like anthropology than genetics, an account of how an isolated village had developed a high occurrence of hereditary deafness that had persisted for over seven generations and how villagers, deaf and hearing alike, could communicate in a sign language they had developed.
Instantly it became a place I wanted to visit.
Finding where the village was in Bali was a challenge in itself, almost maddening. I knew the place existed on Bali, but where? I searched bookstore after bookstore for a map that included the village, finally locating the village as a dot on a Periplus 1:250,000 scale map several kilometres inland on the northern side of Bali.
Like most, my trip started in Kuta, the tourist haunt near Denpasar, the capital of Bali. I crashed for the night in a forgettable cheap room after a long-haul flight. Through blurry eyes the chaos of an Asian tourist destination, the mixed jumble of motorbikes, minivans, people noise and lights brought an odd sensation of being startled but too bone-tired to react.
The next morning’s breakfast was terrible but cheap—in both senses of the word—a reminder of travelling Asia on the proverbial shoestring. I embarked on a round-about trip to North Bali, taking in three bemo (minibus) terminals in Denpasar, but at least things connected well. The traffic was orderly by Asian standards, but the buses were as crowded and slow as anywhere.
Southern Bali is a network of built-up villages; the northern side spreads out a little more thankfully. The bus made its way up to then along the crater ridge of Bali’s feature volcano, Kintamani, with its excellent views through misty wet cloud of the crater and the lake within and then on down towards the northern coast.
Disembarking at Bila, the small town straggled along the roadside in front of me. Bila was clearly a place little visited by tourists. Everyone was out sitting around in the cool of the latter part of the day. They stared at me. A tourist getting off the bus at their stop was clearly an unusual event and I had timed my arrival beautifully for their viewing.
There I asked for local accommodation and how to get to Bengkala. Slowly I got the picture through the language barrier – I’d had no time to learn a little Bahasa Indonesian before visiting – that the turn-off to Bengkala was down the road a bit and that there was no accommodation for me locally. Suprisingly, they indicated that the road to Bengkala was sealed: the map suggested there was no formed road to it. There also appeared to be no losmen in Jagaraja, so the idea of walking through Bengkala onto this well-known temple and staying the night there seemed to be out of the question too.
I decided to walk down to the coast, about 10km away, locate the turn-off to Bengkala on the way and take in the local scene from the roadside. Every little kid insisted on saying “hello”… at first friendly and cute, but rapidly becoming tiring. It’s hard to geninuely be delighted in reply to literally the hundredth “hello” in a short stretch of road. The area was rural, devoted to farming, with advertising hawking chicken farms, inseminators and the like. Despite this, even obviously poor houses had TVs.
One local had a wooden chopping board rigged over the roadside ditch and was cheerfully chopping up a dog for dinner (considered a delicacy in Asia and the Pacific). He waved the knife at me with a big smile in greeting as I passed. People were going about their business without the idiocy of tourism and its trappings.
Eventually I came upon the Bengkala turnoff, which was marked by a large sign and a small crowd of young people hanging out on the corner. I spent some time trying to ask if they knew about the deaf people there, but they were reluctant to give me an answer, making joking remarks about me amongst themselves rather than try understand. The sun was getting low and I moved on.
Eventually I caught a bemo to Sanksit, on the northern coastline, then walked in the dark back to the hotel we passed entering the town. The place was up-market for my budget and proved to be totally empty – no Japanese package tours at the time apparently! Opportunistically I negotiated a deal, good I think considering the quality of the place: a double room with fan, attached bathroom, breakfast, etc. for about $US 5 per night. In practice even lunch was included as the garden staff were happy to offer fresh fruit from around the grounds. Dinner that night was good, if a little expensive for me, shared with four girls travelling in a hired jeep who stopped for a meal en-route to their hotel in Lovina, another beach a little way down the road.
The next day got off to a slow start. After breakfast I wandered around the dusty town searching for sarongs and temple sashes for sale. Not finding any I caught a bemo out to Bengkala, accidentally passing the turnoff and getting off at Bila again, forcing me to walk back down the road for a few kilometres – a little tiring in the tropical heat and damp.
Fewer people were alongside the road, but there still was a small crowd at the Bengkala turnoff; it seemed to be a gathering point of sorts. It was a peaceful little country lane, with markers indicating every 20 metres – a little overdoing it, I thought. As people passed I’d say hello, reversing the kids’ game, watching their reaction – were they deaf? The second group I chanced on were two boys pushing their bikes up the incline. They responded to my “hello” with the sign for “deaf”. Having come so far, it was a welcome relief to see I was on the right track.
A little further down the road I was invited to visit a house off to one side, through a stand of trees. Sitting down at an outside table, with the family and their daughter, a little younger than me, a kid was sent off up nearby trees to get a coconut for refreshments.
After supping coconut juice and halting conversation in a mix of BSL (British Sign Language) and gesture, I was given a tour of the village, calling in on a tiny classroom that served as a school and passing a room with the village’s shared TV. The heart of the village held densely-packed functional buildings. Few people were about when I visited.
I wondered how their deaf coped outside of the village setting. Within the village most knew at least some of their local sign language, but outside the immediate area of the village I imagined few would.
Many—I would imagine most—countries have their own sign language, arising from their deaf communities.
Sign languages differ around the world, although a few have shared ancestry and are as a consequence similar. British Sign Language (BSL) and NZSL are quite similar, for example, and why I could apply a most of what I learnt in England when I returned to New Zealand. American Sign Language (ASL) is, by contrast, is very different to NZSL.
Ethonologue lists 138 sign languages for the deaf. (There are also sign languages for hearing people who elect not to speak, like ‘Hand Talk’ within the Aboriginal population in Australia, and the (mostly historical) use of sign by monastic communities under vows of silence.) Some estimate that there are perhaps 400 signed languages.
Village sign languages are indigenous sign languages in localities with a high frequency of congenital deafness where the sign language is not restricted to the deaf, but are a feature of the village, like in Bengkala where a majority of the villagers, deaf or not, know the sign language. They differ from national sign languages in arising in isolated situations and are typically closely associated with genetic deafness in the village. They aren’t as rare as you might think; even wikipedia lists nearly two-dozen candidates, many now extinct or declining.
They’re found in intriguing places. To name a few: Bedouin tribes in the Negev desert of southern Israel, isolated islands off north-east Thailand, southern Ghana in western Africa.
At the time I visited Bengkala, I was unaware of these other village sign languages. The only other example I knew of was at Martha’s Vineyard. The few people I spoke to about Bengkala at the time had never heard of other examples of village sign languages.
Like many minority languages, these languages are under threat too. One common theme is the younger generation learning their national sign language, favouring that to the village sign language. I’ve read that in Bengkala a school based on Kota Kalok has been established. (There is also Indonesia Sign Language.)
(Young children communicating in Kata Kolak’s new school.)
The nature of genetics of the deafness affects how the sign language involves the hearing people in the village and who those people are.
We have two copies of each gene, one from each parent. Different variants of genes, alleles, are either dominant or recessive. Dominant alleles ‘rule over’ the other, dominating the other, so that the dominant allele determines the outcome of the pair of alleles. In recessive genetic conditions, a single ‘defective’ allele has little effect, playing second-fiddle to the other allele; if one allele is good it is able to provide the normal function on it’s own. People with one defective copy are ‘carriers’ – not having the condition—deafness in this case—but carrying one copy of the gene variant for it. Both copies must be the same recessive allele for deafness to occur. That’s the case in Bengkala.
Children most closely associate with their family. Children with dominant genetic deafnesses will more likely have deaf parents or siblings than children with recessive genetic deafness. The deaf contacts of those with recessive deafness are more likely to be outside their immediate family that those from families with dominant genetic deafnesses.
Village sign languages arise from the village, rather than from within a deaf subset of a much larger community like for the national deaf languages. In hindsight it appealed to me that the language had not arisen from a ‘Deaf’ subculture—which for all their appeal can carry cliquey, even oppositional, politics—but from both hearing and deaf as a community.
Desa Bengkala has been in existance for around 700 years. The sign language is estimated to have been present more than seven generations ago, with the sign language taking hold over the last five generations or so. (Estimates vary.)
(This longer, gently-paced documentary gives an idea of the setting of Desa Bengkala, as well as people communicating using the local sign language.)
Some village sign languages die out when the deafness disperses from the villagers marrying into a wider population, like that happened when the residents of Martha’s Vineyard moved to the mainland. This would be particularly true for recessive deafness where if a deaf person were to marry a hearing person, none of their children would be deaf unless the hearing partner by rare chance was a ‘carrier’, having one copy of the allele for deafness.
Despite the frequency of deaf being a small minority of the population of their village, some of these deafnesses and their village sign languages persist where they might be expected to die out. There are some suggestions that this is, in part, a reflection of small, relatively inbred populations with non-Western cultural habits and marital patterns. One element may be deaf people preferring to marry other deaf people so that the genetics is not in random assortment, as it might for other conditions, but favouring retention of the deafness. Good integration of the sign language in the village would then effectively be making the mutation fitter, or at least less of a disadvantage.
Genetic studies have found that the deaf of Bangkala have in common changes to the DFNB3 region of chromosome 17. These genetic changes have also been found in two unrelated families in India. Other examples have since been found elsewhere, for example in Pakistan, Iran, Brazil and Korea, suggesting this form of genetic deafness has come about independently in different parts of the world.
Variants of the gene for myosin-XVa, which is essential for the development of the stereocilia hair cells in our cochleas, were found in these deaf people.
Stereocilia are ‘hairs’ on the top of the hair cells in the spiral-shaped Organ of Corti in our ears. These hair cells convert movement in the inner ear into into electrical signals that are carried by the auditory nerve to our brains. If the hair cells don’t develop properly, the person won’t be able to hear.
Research suggests one of myosin-XVa’s jobs is to deliver the delightfully-named whirlin protein to the ends of the stereocilia. Whirlin is required for the enlongation of the stereocilia; without it they don’t develop their proper shape. Like mutations in myosin-XVa, mutations in whirlin can also cause deafness.
Whirlin is named after ‘whirler’ mice. Whirler mice are deaf and have a habit of going around in circles – whirling. Variants of this gene cause the traits seen in whirler mice, hence the name whirlin.
Myosins come in two groups. ‘Conventional’ myosins are molecular stepping motors that ‘walk’ along actin fibres. They’re involved in muscle contraction and other processes that move molecules about in our cells. These tiny molecular machines are fascinating to watch in molecular animations.
(This less then 2 minute video by Graham Johnson shows a molecular animation of myosin at work. This process is part of the ‘sliding filament’ model of muscle contraction, where filaments are slid past one another. I’ve included more examples after the videos on Bengkala in the Video Postscript.)
It’s a common theme in the evolution of new functions that existing genes are duplicated and subsequently diverge to distinct roles. Myosins are a large family of proteins. The protein affected in the Bengkala deaf, myosin-XVa, is one of several types of ‘inconventional’ myosins. A detailed understanding of how the mutations in myosin-XVa affect the protein are not yet known.
Village sign languages might also teach us something about the origin of languages.
Some argue that human language arose from gestures, rather than sounds. It’s an intriguing but disputed idea. One observation that might favour it are fMRI studies showing that in ‘native’ signers, who have grown up with sign language from a young age, the signs are processed in the same ‘language’ areas of the brain as spoken languages are. Perhaps human infants have long been evolved to accept both visual and aural input in learning language?
Theodosius Dobzhansky titled an essay, “Nothing in biology makes sense except in the light of evolution”. In village sign languages, in a sense, we see both biological and cultural evolution rapidly occurring from from a disruptive event and how they’ve chosen to cope with it. Rather than the mutation petering out, a compensating adaptation has occurred—the development of the sign language and it’s use by hearing members of the community, as well as the deaf. Where national sign language in some respects isolate the deaf from their hearing community, village sign languages incorporate them.
What future for Bengkala and their deaf? Will Kota Kalok continue to survive?
Reports on line suggest they have prospered in the nearly twenty years since I visited. I hope so and I imagine the research on their sign language has helped to draw support to them. One restraint must be how well the village stands within the wider population over time. In the meantime we can wish them well.
I’ve gathered here a couple of tangentially-related videos that readers might like to view as an extension to my article.
Myosins are also deployed to drag vesicles, tiny sacs of stuff, about the cell. There’s no voice-over explanation in this video unfortunately. The stuff in the sacs have been ‘tagged’ with a fluorescent dye—glowing green—so that the scientist can see them in the cell. The video zooms in until it is inside the interior of a cell and we are watching individual vesicles being dragged along.
While showing different molecules, this molecular animation of transport along microtubule fibres by kinesin molecules (rather than myosin) starting a little after 7 minutes into the video of this TEDx talk by Drew Berry might give you a more of general feel for what myosin molecules do.
Just as I like to wander and peek around in my travels, scientists are explorers, too, drawing together an understanding of how something might work. This article is light exploration of the story behind the deafness at Bengkala.
I’m not a specialist on signed languages or their evolution – please feel free to contribute any corrections or thoughts in the comments below.
I may add further links within the article at a later time; if you think I’ve missed a link, please let me know. (I know I have left out some I would usually include, but I would like to get this article out.)
1. This post has taken longer to get together than I would like; New Zealand Sign Language (NZSL) Week has come and gone. NZSL is New Zealand’s third official language. It is related to BSL (British Sign Language), which I learnt the basics of after my PhD studies in England. At that time, if there were 20 or more people who wanted to learn BSL, the British government provided a teacher. An enterprising student realised you could form a club this way and so did!
2. I’d have to look up old travel logs to remember precisely when I took this trip, but I think it was in the late 1990s. I bought the map of Bali while in Heffers, a British bookstore (for £3.99) and later saw another copy in Stanfords in London.
(Stanfords is legendary amongst travellers to out-of-the-way destinations. Like a bookstore, but it sells only maps. I bought maps for a visit to Northern Pakistan in the early 1990s. The newer US-made maps were (then) not available for public use; Stanfords carried 1960s-era maps I believe they printed from copies of the original plates. The data notes reveal some of the data tracked back to The Great Game, the rivalry between the Russian and British Empires for control of Central Asia that sparked secret mapping expeditions to the western Himalaya, Karakkorum and Hindu Kush mountains ranges. These notes include Eric Shipton – familiar to those who’ve read the romantic (and romanticised) history of this exploration.)
3. Scientific papers are preceded by a summary, an abstract. This potted account lets readers judge if the paper might be of interest to them. The paper is in my files but like most of the world, I’ve since moved to electronic filing. I’d track down the paper to reminiscence, but that’d take time… The abstract was doubly striking because the research was on goitre, not deafness and my recollection is that the body of the paper made no further reference to the remarkable story of these people.
4. Then. I wouldn’t want to count on what it is like now. Having said that, I imagine—or hope—that these villages away from the coast still are true to themselves.
5. Reading this, I can’t help but dream of a roving scientist—Indiana Jones style, of course—tackling the genetics of deafness in these villages on site using a Minion DNA sequencer and doing the computational biology on the road, publishing from exotic locations…
6. Ignoring the genes on our sex chromosomes. In the case of XX women, one copy of the X chromosome is shut down, leaving only one copy of each gene on the X chromosomes accessible to be used. In the case of XY (males), there’s only one of each sex chromosome. The non-sex chromosomes are called autosomes and genetic conditions associated with them are autosomal conditions.
7. See for example Gialluisi et al’s research paper, Persistence and transmission of recessive deafness and sign language: new insights from village sign languages.) You might notice that the locations of the village sign languages I listed in the article with the exception of Martha’s Vinyard are outside ‘Western’ settings.
8. Liang et al., Am J Hum Genet. Apr 1998; 62(4): 904–915. DOI: 10.1086/301786
9. If you’re hunting for it, the gene is MYO15A.
10. I’d tell the story of how hair cells work—it’s a fantastic mix of molecular gadgets—but that would want another article. This one is long enough and I don’t want to get too into too much detail here.
11. On a quick inspection of the research literature. As a tangental note, diagnosis of MYO15A defects is probably under-reported owing to the large size of the gene. (It has 66 exons, coding for 3530 amino acids, spanning over about 71,000 bases.) Another approach would be to exploit the speed and falling costs of modern DNA sequencing and sequence all the coding regions of genes that are being used in the cell (the exome). There are moves in this direction in the deafness research community. Using this approach would be interesting for genetic diagnosis, although it may raise the issue of incidental findings.
12. I’m not a specialist on signed languages – nor the origin of language – please feel free to contribute any corrections in the comments below.
13. Perhaps this is also true for the deaf-blind?, who use tactile signs. I wouldn’t know, but it’s an interesting thought and would extend the range of senses that can be drawn upon to construct ‘language’. [My own speculation at the time I read the first papers showing native SL being processed in the language areas of the brain was that language was identified as patterned signals from any of the main senses, that while one processing area over time grew bound to whatever sense provided these signals, it was open to any of the senses for the source of the linguistic signal. I haven’t followed developments on this, unfortunately, so I’ve no idea what subsequent research has shown.]
14. One local exponent is University of Auckland psychologist, Michael Corballis. You can read some of his ideas on this in his book, From Hand to Mouth: The Origins of Language or his American Scientist article, The Gestural Origins of Language (available on-line). The book’s argument has it’s critics (e.g. in this review) and I’ve no idea of Corballis’ current views, which may have altered as new evidence and lines of thinking have come to light. A recent review (and opinion) of the origin of language can be found in On the antiquity of language: the reinterpretation of Neandertal linguistic capacities and its consequences, in Frontiers in Psychology, e.g. this paragraph:
On the view advanced here, speech and language were largely co-evolving capacities and the study of speech production and comprehension ought to come back to center stage, where it has been displaced by an emphasis on syntax. For example, we need to better understand the genetic foundation for the cortical control of breathing, the tongue, the velum and the vocal folds, for this may give us better clues to the sequence of evolutionary adaptations involved. Absent from other primates, for example, is the lateral cortical system, providing direct connections between cortex and larynx (Fitch, 2010: 350). The idea that human language initially went through a sign-language or gestural language phase has become popular again in part through the discovery of mirror-neurons, offering an apparently automatic translation from manual action to action-understanding (Arbib, 2005). In addition, Call and Tomasello (2007) have cogently argued that ape gesture is connected to intentional communication while ape vocalizations are more reflex signals (as reflected in the lack of cortico-laryngeal connections). Nevertheless, any supposed phase of purely gestural communication must date back at least as far as early H. erectus, and thus a million or more years ago. There is no evidence whatsoever of adaptation of the hand to communicative functions, while there is ample evidence of systematic adaptation of the vocal apparatus to speech, and we have shown that this was more or less in place by half a million years ago. Modern human communication is intrinsically multimodal, using gesture and speech, or at least hand and mouth and face, as evident in any current human interaction—this appears to be a single system. The recurrent natural emergence of sign languages attests to the unified nature of a hand+mouth system, since sign languages merely shift the burden from mouth to hand but use both.
I don’t entirely buy the argument offered in that paragraph (I have only read that portion of the review), as no mention is made of the brain processing signed language as native language, as that suggests visual input has been evolved to be treated as more than ‘just’ gesture, and you might reasonably speculate that the brain adaptation is old. The argument also doesn’t offer that the malleability of the hand can be co-opted for use in sign, rather than specifically being adapted for sign.
15. Dobzhansky is particularly known for his contributions toward the ‘Modern Synthesis’ of evolutionary theory.
Other deafness-related posts in Code for life:
Deafness (A collection of articles by others, originally hoped to be part of a disability blog carnival.)
Bionic ears let the deaf hear (Cochlear implants are extraordinary devices with a surprisingly long history. I’ve included videos of ‘switch ons’, too, – always great to watch people’s reactions to hearing for the first time in many years, or at all.)
Rubella, not a benign disease if experienced during early pregnancy (Written in response to reading a doctor write that rubella had low mortaility or morbidity, seemingly overlooking it can be a cause of congenital deafness, and has been a common cause of deafness in the past.)
Temperature-induced hearing loss (Case studies report that a few individuals lose their hearing temporarily if they have a high temperature. This effect is associated with mutations in the otoferlin (OTOF) gene.)
Minorities, disabilities and scientists (I’m a scientist with a hearing loss. Please excuse that the images are no longer present – I’ve been unable to locate new versions of them, which is a pity as they were great fun.)
World report on disability (Surprisingly—to me—the first world report on deafness was not released until 2011.)
Enabling deaf people to text emergency calls to 111 (Essential services need to be different for deaf people.)