Evolution may have been our planet’s first recycler. When organisms evolved useful proteins, they tend to get re-used in unrelated processes. So, a single family of proteins may regulate the development of everything from the brain to the blood to the bones.

This is one reason that drugs often have off-target effects. While the drug was designed to latch on to a specific protein in one tissue, that protein or a close relative may be doing something important in a different tissue. While that’s generally viewed as a problem, it can also be helpful. Researchers are finding that some drugs can be effective against diseases for which they were never intended.

That may be the case for an asthma medication called clenbuterol. It and a series of related drugs came through a screen that targeted a very different disorder: Parkinson’s disease, caused by the death of specific nerve cells in the brain. And a search through the drug-use history of Norway suggests that the discovery is more than a fluke.