I hadn't encountered this explanation before. I had heard of the underdog theory that we evolved from a primate that adapted to live near, in and around water, which led to human ancestors becoming bipedal, as the only time other apes stand on two feet is when they are in water. And, also it led to hair loss as the loss of hair made it easier to move through water. There are some problems with the ancestors adapted to water environment theory though. Such as other mammals who adapted to water such as otters and beavers did not lose their fur, even if dolphins and whales did lose the littel fur they had when they re-entered a water environment way back in their evolutionary development.