Is blood plasma salinity the same as seawater? No, but that proves evolution. "The answer is most definitely NOT that oceans were 1/3 as salty back then. It most definitely IS that the earliest vertebrates did evolve in salt water and then moved into fresh water....They have devised an extremely clever trick in kidney structure to allow salt transport pumps which really take salt back INTO the body from the urine but still manage to use them to produce urine much more concentrated that their body fluids and so excrete salt FROM the body."
posted by Brian B.
on Feb 10, 2007 -