Rein has carved a niche doing just that. He’s very much a “real scientist”, who has published in peer-reviewed journals, and did a post-doctoral fellowship at Stanford, where he still teaches. But he’s also a communicator, explaining the complex, imperfectly understood science of the brain in simple but compelling terms. He has 755,000 followers on TikTok and is a regular podcast guest, discussing audience-friendly, often-controversial topics: the causes of autism, empathy, recreational drug use and now, the subject of his first book, Why Brains Need Friends: The Neuroscience of Social Connection.