It’s a devastating disease, changing behavior, causing uncontrolled movements, blindness, coma, and, finally, death. And we all have the makings of it in our heads.
When it topples cows, it’s known as mad cow disease. The human form is called Creutzfeldt-Jakob disease. In sheep, it’s scrapie. It’s a rare malady caused by a misshapen protein known as prion protein, or PrP. The big mystery is why people, cows, sheep, and other mammals have so much of the protein in their bodies, particularly in the brain.
“It’s intriguing to find that PrP, which,...