A nice article in Scientific American by Dana Smith looks at a new study of language development in the Tsimané people of Bolivia: “Parents in a Remote Amazon Village Barely Talk to Their Babies—and the Kids Are Fine”.
The researchers observed, anecdotally, that language development appears to be slightly delayed in the Tsimané—but this does not seem to matter. The children grow up to be fully functioning, communicative and productive members of the community. In fact, as interactions between Tsimané and other Bolivians increase, many of the children are becoming bilingual in Spanish as well at their native Tsimané language.
This is a good story of the way that differences in childrearing across cultures have unpredictable outcomes, and what has been recommended within particular Western societies may not generalize to other places.