evidence: You’ve almost certainly heard about Toxoplasma gondii before, the dreaded cat poop parasite that’s infected roughly 2 billion people around the world and famously makes mice unafraid of cats. Researchers have found evidence suggesting Toxoplasma gondii infection in humans is responsible for everything from depression and suicide, to impulsive and aggressive actions, to maybe even some forms of psychosis. And perhaps those bits of research give some clue as to why we’re now seeing headlines about a new study published Wednesday in Proceedings of the Royal Society B suggesting this parasite promotes entrepreneurship. [...] For the uninitiated, Toxoplasma gondii is a parasite that gets excreted in cat feces and has been shown to infect virtually any warm blooded animal that comes into close contact, although the parasites can only reproduce in felines. The parasite has been shown to alter rodent behavior by making them less risk-averse. Infected mice will spend more time exploring mazes, and are even attracted to cat urine—behaviors that greatly raise the chances of being attacked and eaten by a predator. Infected animals also develop cysts in their brains that alter levels of certain neurotransmitters and hormones, resulting in higher levels of dopamine, serotonin, testosterone, and other signaling molecules that reduce fear in rodents and presumably affect judgement, personality, and mental health in any infected hosts.