This past spring, Christian Schaaf sat back and watched seven-year-old Lily play in his office at the Baylor College of Medicine in Houston. She looked just like any other girl her age, he recalls, but she didn’t seek interaction or even eye contact in the way a child normally would. Instead, she communed with a corner of the room, excitably hopping and flapping her arms as if that spot held a treat too great to bear. Without peering into the file in front of him, Schaaf knew what afflicted Lily. “I’ve seen enough children that when I see someone with autism, I have a high suspicion for it,” he says.