Perhaps semi-aquatic isn't specialization I doubt that the aquatic theory can ever be proven or disproven. The evidence is intriguing but hardly convincing. That said, and for the sake of science, I don't think the quoted paragraph holds water. (Yuk) As I said earlier, life in a three dimensional environment seems to be a stimulus for increasing intelligence. The hominids that crawled out of the lake and resettled on land undoubtedly had some physical disadvantages, but it's possible that their IQs had risen high enough to more than compensate and allow them to quickly surpass their cousins who never got their feet wet. And just how big a disadvantage is a lifestyle that's only SEMI aquatic? You've got to be versatile and have two sets of well toned muscles. That could be an advantage! Polar bears are not just semi-aquatic but semi-marine, a pretty challenging combination of milieux. Yet in the few centuries since civilization began closing in on their habitat, they have proven just as clever and adaptable as the other ursines. At night they figure out how to open the latest model padlocked dumpster, and during the day they pose for cute tourist photos so the humans don't put much energy into running them off.