The converse of the anthropic principle seems reasonable. The imbalance is not due to the existence of humanity; but humanity cannot coexist with large amounts of antimatter, and so one could say that humanity is due to the imbalance. If the local imbalance = A and the existence of humanity = B, then (not A) implies (not B), so B implies A, even though the chain of causality runs A allows B. Slightly more accurately, regardless of the general composition of the universe, the only part of the universe with which we an have direct contact is that part which has much more matter than antimatter. This accounts for why there must be more matter than antimatter in our local sector of the universe- better to say, in any sector that contains life, of which we must inhabit one. As for the actual mechanism by which the imbalance came to be, I have absolutely no idea.