  While Kegl et al. endorse the language bioprogram hypothesis that ISN emerged ‘in one leap,’ in the minds of children exposed  to degraded Mimica or LSN inputs, their data are equally consistent  with the idea that ISN developed more gradually by means of  successive elaborations and innovations among a community of  highly-motivated (because language-starved) young users. Indeed, as  Kegl et al. themselves describe the history (p.187), this is  precisely what happened. First, a group of signers, each with his or  her own idiosyncratic form of Mimicas, entered the schools. Members  of this group gained in expressive power as their individual Mimicas  were enriched by borrowings from others' homesign systems. Then, a  new cohort of Mimicas signers entered the schools. Their sign systems benefitted both from exposure to the Mimicas of their peers and from  exposure to the richer system developed by the earlier group. Through a process of successive elaborations in this manner, LSN developed  and then, by a similar series of steps, ISN developed. At present,  all three sign systems are still being used in Nicaragua, presumably  reflecting the different ages at which people are exposed to language and the kinds of inputs (ISN or LSN vs. signed and written Spanish or lipreading in regular schools) they receive. In addition, ISN and to  a lesser extent LSN are still constantly changing — as one  would expect if ISN were a community-wide work in progress, not the  finished product of an individual child's mind,