How does a person recognize an exceptionally bright child (under age 8) when there is no literacy/schooling?

So for example, there is a family in some tribe in Mali (a country in Africa, for those who don't know). There's a young child in this tribe who is extremely intelligent, but there is no schooling or literacy at all. Formal schooling is just not in the tribe's culture, and it's so remote that missionaries haven't built something there yet. So how would a parent recognize that their child is brilliant? How does genius show itself outside of education?