Genetic stories behind village sign languages

Transcription

1 Genetic stories behind village sign languages the co-evolution of deafness with sign language June, 2013 Minerva-Gentner Symposium on Emergent Languages and Cultural Evolution Berg en Dal, The Netherlands Dan Dediu Language and Genetics Max Planck Institute for Psycholinguistics Nijmegen The Netherlands Dan Dediu 1

2 Overview Genetic mechanisms in hearing loss DFNB1 (ABSL) and DFNB3 (Kata Kolok) Models of genetic hearing loss and sign language The origins, evolution and stability of village sign languages Overview Dan Dediu 21

3 Many types of hearing loss Genetic mechanisms in hearing loss Drugs Infections Acquired Aging Hearing loss Head injury Noise Congenital Prenatal infections Genetics Genetic Dan Dediu mechanisms in hearing loss 13

4 Genetic mechanisms in hearing loss Many types of hearing loss genetic role Drugs Infections Acquired Aging Hearing loss Head injury Noise Congenital Prenatal infections Genetics Genetic Dan Dediu mechanisms in hearing loss 14

5 Some examples: TECTA TECTA Dan Dediu 51

6 Tectorial membrane: collagen Some examples: TECTA TECTA Dan Dediu 61

7 Some examples: TECTA Tectorial membrane: collagen non-collagenous proteins α-tectorin TECTA gene (11q23.3) TECTA Dan Dediu 71

8 Some examples: TECTA Tectorial membrane: collagen non-collagenous proteins α-tectorin mutations TECTA gene (11q23.3) TECTA Dan Dediu 81

9 Some examples: TECTA Tectorial membrane: collagen non-collagenous proteins α-tectorin DFNA12 - dominant TECTA gene TECTA Dan Dediu 91

10 Some examples: TECTA Tectorial membrane: collagen non-collagenous proteins α-tectorin DFNA12 - dominant DFNB21 - recessive TECTA gene TECTA Dan Dediu 1

11 Some examples: mitochondrial 12S rrna MTRNR1 Dan Dediu 1

12 Some examples: mitochondrial 12S rrna MTRNR1 Dan Dediu 1

13 Some examples: mitochondrial 12S rrna Own genetic code own translation machinery own ribosomes Small subunit ribosomal RNA MTRNR1 Dan Dediu 1

14 Some examples: mitochondrial 12S rrna Mitochondria ancient bacteria (endosymbiotic theory) MTRNR1 Dan Dediu 1

15 Some examples: mitochondrial 12S rrna Mitochondria ancient bacteria (endosymbiotic theory) mitochondrial ribosomes are very similar to bacterial ribosomes Mutations (e.g. A1555G) even more similar modifiers MTRNR1 Dan Dediu 1

16 Some examples: mitochondrial 12S rrna Hair cells are more affected by mitochondrial ribosomal impaired function more than other cells? specific phenotype Mutations (e.g. A1555G) even more similar modifiers MTRNR1 Dan Dediu 1

17 Congenital non-syndromic deafness Many loci (e.g., Autosomal dominant: DFNAnn (~25) 0% 50% 75% 100% 100% 100% Congenital Dan Dediu non-syndromic deafness 1

18 Congenital non-syndromic deafness Many loci (e.g., Autosomal dominant: DFNAnn, recessive: DFNBnn (~40) 0% 0% 25% 0% 50% 100% Congenital Dan Dediu non-syndromic deafness 1

19 Autosomal recessive 13q12.11 DFNB1A/B (GJB2 and GJB6) GJB2 (Gap junction beta-2; Connexin 26) and GJB6 (Gap junction beta-6; Connexin 30) DFNB1A/B Dan Dediu 1

20 Autosomal recessive 13q12.11 DFNB1A/B (GJB2 and GJB6) GJB2 (Gap junction beta-2; Connexin 26) and GJB6 (Gap junction beta-6; Connexin 30) GJB2: ~90 mutations non-syndromic deafness other mutations: syndromes (skin + deafness) GJB6: some mutations non-syndromic deafness other mutations: skin disorders potassium levels in the inner ear? DFNB1A/B Dan Dediu 21

21 DFNB3 (MYO15A) Autosomal recessive 17p11.2 MYO15A (unconventional myosin-15; myosin XVa) sterocilia DFNB3 Dan Dediu 21

22 DFNB3 (MYO15A) Autosomal recessive 17p11.2 MYO15A (unconventional myosin-15; myosin XVa) sterocilia DFNB3 Dan Dediu 21

23 interaction transport DFNB3 (MYO15A) Autosomal recessive 17p11.2 MYO15A (unconventional myosin-15; myosin XVa) sterocilia EPS8 DFNB3 Dan Dediu 21

24 DFNB3 (MYO15A) Autosomal recessive 17p11.2 MYO15A (unconventional myosin-15; myosin XVa) sterocilia A2674T mutation non-functional protein abnormal stereocilia hearing loss DFNB3 Dan Dediu 21

25 ABSL: population & evolutionary genetics Al-Sayyid Bedouin community ~200 years ago 3 rd generation ~3,500 members ~3.3% deaf members social integration ABSL L2 for hearers ABSL Dan Dediu 21

26 Kata Kolok: population & evolutionary genetics Bengkala village, Bali ~ (?) years ago ~10-20(?) generations ~2,200 members ~2.2% deaf social integration KK L2 for hearers Kata Dan Kolok Dediu 21

27 Recessive hard to predict ABSL & Kata Kolok 0% 0% 25% 0% 50% 100% ABSL Dan & Dediu Kata Kolok 21

28 Recessive hard to predict ABSL & Kata Kolok Non-syndromic no other ill effects ABSL Dan & Dediu Kata Kolok 21

29 ABSL & Kata Kolok Recessive hard to predict Non-syndromic no other ill effects Inbreeding increasing frequency ABSL Dan & Dediu Kata Kolok 21

30 ABSL & Kata Kolok Recessive hard to predict Non-syndromic no other ill effects Inbreeding increasing frequency Social integration increased biological fitness ABSL Dan & Dediu Kata Kolok 31

31 ABSL & Kata Kolok Recessive hard to predict Non-syndromic no other ill effects Inbreeding increasing frequency Social integration increased biological fitness True gene-culture co-evolution ABSL Dan & Dediu Kata Kolok 31

32 ABSL & Kata Kolok Recessive deafness long-term high frequency What can we say about these parameters? Emergent generalized sign language Increased biological fitness of deafness mutation ABSL Dan & Dediu Kata Kolok 31

33 Models of sign language genetics Gene-culture co-evolution tradition Genetic epidemiology approach Critique and perspective see tomorrow Alessandro Gialluisi's talk Models Dan Dediu 31

34 Gene-culture co-evolution Series of papers: Aoki, K., & Feldman, M. W. (1991). Recessive hereditary deafness, assortative mating, and persistence of a sign language. Theoretical population biology 39: Feldman, M. W., & Aoki, K. (1992). Assortative mating and grandparental transmission facilitate the persistence of a sign language. Theoretical population biology 42: Aoki, K., & Feldman, M. W. (1994). Cultural transmission of a sign language when deafness is caused by recessive alleles at two independent loci. Theoretical population biology 45: Gene-culture Dan Dediuco-evolution 31

35 Gene-culture co-evolution Basic ideas: Sign language: monolithic cultural trait an individual has it or not transmission: vertical, oblique, horizontal learning: both parents sign prob. b and c single parent sings reduced by l oblique: f and g horizontal: h and i maternal grandparents... Gene-culture Dan Dediuco-evolution 31

36 Gene-culture co-evolution Basic ideas: Genetics: diploid biallelic locus genotypes AA, Aa and aa A dominant aa deaf from birth allele frequencies: p (A) and q (a) fraction of assortative matings: m by deafness by sign language use Gene-culture Dan Dediuco-evolution 31

37 Gene-culture co-evolution Other assumptions: equilibrium 0 < p, q < 1 (later, q << 1) 0 m < 1 0 b c 1 0 < l 1 Gene-culture Dan Dediuco-evolution 31

38 Gene-culture co-evolution Conclusions: If sign language cannot jump a generation : Assortment by deafness helps persistence Assortment by signing hinders persistence Dominant helps more than recessive Horizontal & vertical don't seem to matter Grandparental transmission (language can jump ): Assortative mating high grandparental transmission helps Gene-culture Dan Dediuco-evolution 31

39 Gene-culture co-evolution Conclusions: If sign language cannot jump a generation : Assortment by deafness helps persistence Assortment by signing hinders persistence Dominant helps more than recessive Horizontal & vertical don't seem to matter Grandparental transmission (language can jump ): Assortative mating high grandparental transmission helps assortative mating by deafness helps most! Gene-culture Dan Dediuco-evolution 31

40 Genetic epidemiology Series of papers: Nance, W. E., Liu, X. Z., & Pandya, A. (2000). Relation between choice of partner and high frequency of connexin-26 deafness. Lancet 356: Nance, W. E., & Kearsey, M. J. (2004). Relevance of connexin deafness (DFNB1) to human evolution. Am J Hum Genet 74: Arnos, K. S., Welch, K. O., Tekin, M., Norris, V. W., Blanton, S. H., Pandya, A., & Nance, W. E. (2008). A comparative analysis of the genetic epidemiology of deafness in the United States in two sets of pedigrees collected more than a century apart. Am J Hum Genet 83: Genetic Dan Dediu epidemiology 41

41 Genetic epidemiology Basic ideas: Assortative mating by deafness Relaxed selection against deafness Relaxed selection (increased fitness) Introduction of sign languages & deaf institutions Assortative mating Increased frequency of DFNB1 deafness Genetic Dan Dediu epidemiology 41

42 Genetic epidemiology Compare E.A. Fay's 19 th century data on deafness With 21 st century data from a comparable sample Genetic Dan Dediu epidemiology 41

43 Genetic epidemiology Compare E.A. Fay's 19 th century data on deafness With 21 st century data from a comparable sample dramatic increase (~5 times) over 100 years linear increase over the last 60 years not assortative mating for deafness per se but linguistic homogamy father mother proband Genetic Dan Dediu epidemiology 41

44 Genetic epidemiology Computer simulations: Agent-based, non-overlapping generations 3 recessive loci Deafness fitness, f Assortative mating proportion, m Fixed population size (200,000 agents) Fixed sex ration (1:1) Genetic Dan Dediu epidemiology 41

45 Genetic epidemiology f = 0.0 m = 0% f: 0 1 M: 0% 90% f = 1.0 m = 90% Genetic Dan Dediu epidemiology 41

46 Genetic epidemiology Frequent gene Infrequent genes: - linked to Cx - unlinked to Cx f = 0.0 m = 0% f: 0 1 M: 0% 90% f = 1.0 m = 90% Genetic Dan Dediu epidemiology 41

47 Genetic epidemiology Conclusions: Assortative mating + relaxed selection increase frequency Linguistic homogamy Initially higher freq. genes disproportionately amplified Genetic Dan Dediu epidemiology 14

48 Genetic epidemiology Conclusions: Assortative mating + relaxed selection increase frequency Linguistic homogamy Initially higher freq. genes disproportionately amplified assortative mating for sign language/linguistic homogamy Genetic Dan Dediu epidemiology 14

49 The origins, evolution and stability of village sign languages Conditions & models Alessandro Observation 1: many potential genes why do so few get used (DFNB1, DFNB3...)? Observation 2: Endogamny/inbreeding is not infrequent why so few village sign languages? Observation 3: Most seem relatively young where are the old ones? The Dan origins, Dediuevolution and stability of village sign languages 41

50 The origins, evolution and stability of village sign languages probably the village sign languages are fragile: genetic conditions (inbreeding, assortment) cultural conditions (social acceptance) linguistic conditions ( critical mass ) most appear, flicker and disappear special conditions for their long-term maintenance if they are good models for language origins & evolution then maybe language appeared multiple times and died out The Dan origins, Dediuevolution and stability of village sign languages 51

51 Thank you! Questions? Special thanks to Steve Levinson, Connie de Vos, Alessandro Gialuisi, Clyde Franks & Simon Fisher End Dan Dediu 51