When was use of salt started by humans in diet?

Answer 1

I'd have to say that salt has always been in use. Besides needing sodium for our nervous system to function, we have an evolutionary yearning for it, like we do for fat. Foods that contain salt and fat taste better to us than those that don't. I don't know when it started being used for preservation (for drying food out), but this knowledge has existed since at least the ancient Egyptians were around (at least 3000 B.C.E.), as they used it in part to preserve their mummies.