Will My Cat Eat My Eyeballs?: And Other Questions About Dead Bodies

by Caitlin Doughty

Rigor mortis is the Latin name for the stiffening of the muscles that starts around three hours after death (even sooner in very hot or tropical environments). I’ve been studying rigor mortis for years and I’m still not sure I totally understand the science of it. The muscles in your body need ATP (adenosine triphosphate) in order to relax. But ATP requires oxygen. No more breathing means no more oxygen, which means no more ATP, which means the muscles seize up and can’t relax. This chemical change, collectively called rigor mortis, starts around your eyelids and jaw and spreads through every muscle in the body, even the organs. Rigor mortis makes the muscles incredibly stiff. Once it sets in, that body ain’t movin’ from whatever position it is in.