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. Author manuscript; available in PMC: 2008 Oct 7.
Published in final edited form as: Curr Biol. 2005 Jun 21;15(12):R463–R465. doi: 10.1016/j.cub.2005.xx.xxx

Table 1.

Social conditions under which signed communication systems emerge.

Situation Number of people Number of generations Number of years Learners’ age at first exposure Input to current learners Hearing status of interlocutors Context for transmission to new generations
Al-Sayyid Bedouin Sign Language 10 in first generation 150 to date 3 70 Birth 2nd generation signing Deaf and hearing Multi-generational family home
Homesign 1 1 Individual lifespan Birth Co-speech gesture Hearing None
Nicaraguan Sign Language 50 in first cohort 800 to date 1 (in 3 cohorts) 25 5 2nd cohort signing Deaf School and urban community
American Sign Language Hundreds of thousands 8 200 Variable Full language Mostly deaf Family home, school, and larger community
Optimal situation High High High Low Full language Unknown Frequent close contact, older to younger