The human primate body— bald and bipedal, with large brain, nose, and blubber — probably evolved due to a freak island accident. 

Imagine meeting a married couple in a nursing home. They are both in wheel chairs and have grotesque faces, skin, and hair, and are missing some body parts. You might imagine all sorts of medical explanations for their conditions. But the parsimonious explanation is that they were together in a car that crashed and burned. 

Such is probably the case with the human body. All the "grotesque" human features (compared to other primates) can be explained by a single freak accident where a few chimpanzees became isolated on a Galapagos-like island off the west coast of Africa. Their descendants lived on the shores of that island for millions of years, diving for shellfish and sea vegetables. Their main diet was an unlimited supply of sea-turtle eggs on the beaches around the 150-kilometer shoreline. With no predators, competitors, or African viruses on the island, they became a huge population that evolved the unique human traits. 

You can read about this unorthodox hypothesis for human evolution here: A Paradigm for the Evolution of Human Features: Apes Trapped on Barren Volcanic Islands.