I have taken an interest in the aquatic ape theory of human origins since it first appeared without ever being really convinced. However, since some people in sci.anthropology.paleo seem to be enjoying a bit of wild speculation, I would like to add a thought.
I usually see the aquatic ape theory portrayed in terms of pre-humans taking to the oceans or at least the African rivers and lakes like seals. That always seemed unlikely for a couple of reasons. Crocodiles for one.
Most city living academics have no idea how dangerous it is to go near the water anywhere where there is a healthy population of crocodiles.
Then there is the fact that the human form is a lousy design for an swimming mammal. Even with mask, snorkel and swim fins we are barely viable in the water.
What we are, is a superb wader design. Just check any wading bird against the human design. Even now, wilderness survival is easiest along a shore, provided you have a few basic skills.
This even ties in with the strange ability of human babies to float and swim. The baby of a wading mother would have a strong motivation to evolve the ability to float if dropped.
As to why a chimpanzee would try to become a heron; I can only guess that at some time there was a big, empty ecological niche for a wading ape. This was unlikely to have been along the African rivers because of the crocodiles.
I suspect that the ocean shore and salt lakes may have been that niche. No crocodiles remember, and salt caking in fur would probably make salt lakes miserable for animals with much hair or fur so no competition from hyenas.
Oh! And about a billion flamingos to eat.
Another interesting thought. During the Deep Sea Drilling Project, (1964-83) the Glomar Challenger discovered that the Mediterranean had dried up several times.
This would have produced a huge area of low desert, salt marsh and salt lakes. Maybe, just the environment to tempt a bunch of jumped up chimps.
Oddly, wading adaptations (mostly bipedalism and reduced body hair) would be quite useful on the savannas.
Of course, all this theorizing falls flat on its face if pre-humans
never went near water except to drink.