[winchling]

>Someone has to know what other people ate, know what of what they ate killed them, remember that, pass it on, and be believed for that to work.

Yes, this is the tricky part. Per the article, such knowledge is passed on culturally, i.e. by people imitating their betters. But that's not the whole story. My guess is that occasionally, in unusual circumstances, some wise person would step in and say, 'No, don't do that!' (without necessarily being able to explain why).

An important clarification is that, contra the article, people can't literally imitate other people. Rather, they guess the meaning of other people's behaviour. Again, without necessarily being able to explain it or even state it in words. See Chapters 15,16 of The Beginning of Infinity, by David Deutsch.