Have you ever been so intrigued by (or scared of) someone that you felt the need to analyze their poop? Joseph Stalin's answer to this question was apparently yes. As Steven Rosenberg writes for the BBC, a former Soviet agent has revealed that the dictator had a top secret program to analyze the excrement of other foreign leaders during the 1940s.

Rosenberg reports that documents in the archives of the Russian Secret Service reveal evidence of a secret laboratory that put Soviet scientists to work studying the excrement of world leaders. The idea was that traces of various compounds in feces could give insights into each person's psychology.

The documents reportedly show that scientists obtained illicit samples of Mao Zedong’s excrement during a visit to Russia in 1949. The agent who conducted the research claims that Soviet operatives installed special toilets that were linked not to plumbing systems, but rather to boxes to collect the feces.

Rosenberg writes that after reading an analysis of Mao's excrement, “Stalin reportedly poo-pooed the idea of signing an agreement with him.” The Russian Secret Service refused to comment on the claims.

Perhaps Stalin was ahead of his time—after all, these days, feces are all the rage among scientists eager to uncover the secrets of the human microbiome. Commercial services that let you send poop for analysis exist as well (though the results sometimes leave a lot to be desired). And in Japan, you can even relieve yourself in a fancy toilet that then analyzes your excrement and sends you a URL with information about everything from your body fat to the bacteria in your guts. The shape and color of your stool also contains clues about what’s going on inside—that is, if you have the stomach to examine it.

Historians believe that Mao and Stalin had an uneasy relationship characterized by awkward meetings and deep divisions on things like foreign policy and Marxist ideology. But there might be a smellier side to the story.