Where, when, & why did humans originate?

Allan Krill

The earliest Y-chromosome DNA (A00) and language (Khoi-San with 'clicks') are in west Africa, from about 200,000 years ago.
But how could anatomically modern humans suddenly start there, having left no fossil record of their earlier history?  
I think humans evolved on Bioko Island in a Galapagos-like scenario.

Chimpanzees live in western Africa where there are no fossils of any mammal, because bones decay too fast. About 6 million years ago, a few chimps accidentally rafted 32 km to the volcanic islands of Proto-Bioko. There were no trees or predators. Their only food was seaweed, shellfish, turtle eggs and turtle meat: hundreds of huge sea-turtles visit the beaches each night to lay eggs.

Those 'aquatic apes' changed during the first million years: they evolved a bald body, blubber, large buoyant brain from marine DHA-fat, human nose, descended larynx and breath control for diving and speech, multipyramidal kidneys for excess salt, and all the other uniquely human traits.  

During the next 5 million years, I envision a population of 10,000 fat naked humans on Bioko. It was an easy life, mostly in the water, singing about turtles, sharing food—self-domesticating. It's rainy on Bioko, warm day and night, year round. They needed no clothes, tools, weapons, or fire.

Some early explorers (e.g. 'Homo Erectus', 'Neanderthals', and others) swam to the mainland. Most stayed on Bioko until about 200,000 years ago, when they used a Pleistocene land bridge to walk over. They invented clothes, weapons, and fire, needed to survive in all other environments.  

Allan Krill, Ph.D.
        Read Krill's Anthropogeny blog for details.        See also AquaticApe.net