Quote:
Originally Posted by octopus
There is one thing I cannot understand about Aquatic Ape hypothesis.
It claims that spending time in/around the water brought some evolutionary adaptations to humans. Assuming this is true, I wonder why our eyes did not adapt for underwater vision also. Eyes do adapt very quickly and it would take fairly modest change (evolutionary speaking) to see better underwater. Considering vision is the sense primates most rely on (our “top” sense) it seems it would have been under high evolutionary pressure (hence speeding it up).
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CiteULike: Visual training improves underwater vision in children.
Since evolutionarily "recently" developing primitive boats and nets (whereby sitting/wading becoming more significant than diving) became employed for food foraging; diving and underwater vision have been under much less selection pressure. The high degree of nearsightedness/farsightedness in humans (not in plains dwelling animals) may indicate that childhood was once a period of visual plasticity.
Human ancestors did not become fully aquatic like whales, nor semi-aquatic specialists like sea lions (with their large round bulging eyes), but they maintained a general association with shore resources (waterside ambush of large game, mangrove oyster prying, sand clam digging, sea turtle egg digging) and off-shore food foraging (reef diving for molluscs, fish, crustaceans, sea urchins, kelp, aquatic plants), as well as inland foraging (fruits, nuts, flint for cutting tools), as omnivores; able to jog along beaches, wade in shallows, swim to nearby islets, dive more than a meter deep, backfloat while resting and nibbling, climb coconut palms and figs, climb rocky shore cliffs (caves, sea bird eggs, berry bushes), etc. Developing specialized aquatic vision like dolphins would have interfered with these mixed activities.
"Aquatic ape" does not mean fully adapted aquatics, but rather that our ancestors became the most water-associated of the known hominoids, while the others became more forest-associated or inland marsh-associated.
DDeden
