In a new study of mouse brains, scientists show that the patterns of gene regulation stimulated by salt cravings are the same gene patterns regulated by drug addiction.

Salt appetite is a craving millions of years in the making, with likely roots in the salty seas where life on Earth began. (Related: "Is Salt Nature's Antidepressant?")

"Land dwellers face a problem in that sodium is a trace element, so they have to have a strategy to ingest sodium, and salt craving or sodium appetite is evolution's answer to that," said study co-author Wolfgang Liedtke, an assistant professor of medicine and neurobiology at Duke University.

Salt appetite can be so strong that animals short on sodium will put life and limb