3 ms·
That's all true, but you're merely describing the status quo. I'm asking why our kidneys (and those of most other mammals) have not evolved to process sea water
by fauigerzigerk 9y ago
That's all true, but you're merely describing the status quo. I'm asking why our kidneys (and those of most other mammals) have not evolved to process sea water.
Apparently there was not enough evolutionary pressure and that is what I find very surprising.
- jacquesm 9y agoThe subjects to study would be Cetacea, there should be at least a partial answer there: https://en.wikipedia.org/wiki/Cetacea https://en.wikipedia.org/wiki/Cetacea There is this bit: "The kidneys are long and flattened. The salt concentration in cetacean blood is lower than that in seawater, requiring kidneys to excrete salt. This allows the animals to drink seawater." So for those animals that returned to the sea from the land that pressure was there and they seem to have adapted in that sense. Humans - and most other mammals - being land dwellers we always had access to rivers and rainfall both of which are fresh.