Mailbag: Hidden lactase persistence alleles?

I just noticed this new article that I thought you might be interested in, suggesting that lactase persistence known genetics can't currently wholly explain the trait in large regions around Africa and Europe:

Thanks. I’ve been studying that one for a couple of days. It looks like pretty suggestive evidence that there should be some as-yet-undiscovered lactase persistence allele in West Africa, or maybe a gene conversion from one of the already-known African mutations.

See also Razib on this paper: