Hummus. Chewbacca. Belly button. These are just a few of the thousands of words scientists painstakingly decoded from over 2,100 hours of recorded conversations to determine if the amount of language kids hear explains why girls have bigger vocabularies early in life. It doesn’t. Instead, the scientists found that caregivers just talk more to toddlers after they say their first word, which suggests that children actively influence their own language development.