I saw a documentary on a swedish channel about a year ago about exactly that.
I thought there was one striking thing speaking for it. Humans must eat several essential organic compounds since our body can't produce them. (Dont remember which now) The apes didn't need to eat those compounds since their bodies did make them. Those compounds were found in aquatic living animals (food).
Also that apes cannot eat crayfish, shrimps and so on. Something in it that their digestion can't handle, but humans have no problem with it.