“Language does not fossilize and as yet the gap between the two-word signs of an educated chimpanzee and the sensible chatter of a three-year-old is bridged by no more than speculation”
— Colin Patterson
As with species, languages are also altered over the years by gradual evolutionary processes. They are also subject to extinction, but evolve horizontally, namely by borrowing from other languages or by migration processes.
The attempts to educate young chimpanzees had some success only when the animals learned sign language. Chimpanzees cannot reproduce spoken language because their anatomy does not enable them to speak. Their tongue and larynx are like those of a newborn baby. However, unlike babies, this does not change over time in chimpanzees.