Do psychological conditions vary by sex? More boys are diagnosed with autism, and more girls with depression. Scientists at the university of Rochester Medical Center want to understand any such sex differences. So the researchers studied smell and gender in nearly microscopic roundworms. What can we learn about our brains from tiny worms? Well, these creatures have a relatively simple and well-mapped nervous system. Some are male, and some are hermaphroditic. Scientists presented the worms with two scents. One smelled like buttery popcorn, another like green vegetables. Hermaphrodites mostly crawled towards buttery popcorn, while males preferred vegetables. Then scientists manipulated some of the hermaphroditic neurons to behave like they were male. And the newly male worms now crawled towards the green peppery smell. What does this tell us about male and female human brains?