An analysis of students in the US has found that those who have a certain type of brain parasite are more likely to be majoring in business studies. Toxoplasma gondii is a protozoan parasite carried by cats. It can infect people through contact with cat faeces, poorly cooked meat, or contaminated water, and as many as one-third of the world’s population may be infected. The parasite doesn’t make us feel sick, but it forms cysts in the brain where it can remain for the rest of a person’s life. Some studies have linked infection with the parasite to slower reaction...