This theory explains many features of modern man simultaneously; the ability to wade deeper and deeper would obviously have direct relation to a bipedal. But more interestingly, a large amount of time spent in the water would also explain two other distinguishing features of man in relation to his more ape-like cousins. A reduction in the amount of hair covering the body would allow for an easier transition between surf and shore, also allowing for greater agility in the water (it is also interesting to note, that the hair on a human's back, unlike that of a gorilla or chimpanzee, points down and inwards, following very much the pattern water would make while passing around the head). The other feature distinguishing human from other apes, is their subcutaneous layer of fat. This layer of fat is very similar to a whale's blubber, and serves as, essentially, a waterproofing device, allowing very large amounts of time to be spent in the water. No other ape has this feature, and all other apes have a very strong aversion to water, contrasting greatly with humans and especially their infants, who become amazingly adept in the water in very a very short period of time. .
Our large brains and complex communication skills could also be attributed to Natural Selection. Not being particularly well armed with the speed, teeth, or claws of most other successful predators, man would have needed coordination and cooperation with each other when it came to hunting. Larger brains would have allowed for more complex strategies, as well as the improved ability to communicate with others. Those possessed of larger and larger brains would have been more apt at sustaining themselves and creating more successful social settings. .
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More modern applications of Natural Selection can be seen in the case of sickle-cell anemia. While rare in North America, sickle cell is common in areas where malaria is prevalent.