sign-language

In addition to Ameslan, chimpanzees and other nonhuman primates are being taught a variety of other gestural languages. And it is just this transition from tongue to hand that has permitted humans to regain the ability-lost, according to Josephus, since Eden-to communicate with the animals.

I would expect a significant development and elaboration of language in only a few generations if all the chimps unable to communicate were to die or fail to reproduce. Basic English corresponds to about 1,000 words. Chimpanzees are already accomplished in vocabularies exceeding 10 percent of that number.