one thing youve seemed to of overlooked when you used giant turtles as an example. the giant turtle has been on this planets 1000s if not millions of years longer than the human race. the giant turtles have had a much longer time period to be exposed to mutations than we humans. like someone pointed out earlier the humans average life a few hundred yeards was only in the 40s now it is in the 70s for males and 80s for females yet many humans are living to they are in their 100s. we humans are still merely children