dr. louise greenspan a pediatric endocrinologist at kaiser permanente in san francisco.hanks for being here today. >> thanks for having me. >> why is it important to study early puberty? >> doctors have noticed girls are going through puberty earlier in the past. we didn't know exactly how early. we had never been able to follow one group of girls going through development. we didn't know what was happening to each girl as they went through. so we've had the opportunity now to study one group of girls, 1200 girls across the country, and look at them over time to see what's happening. and even though i'm a specialist in puberty, when i see one girl in the office i don't necessarily know what's happening with the larger group of girls. so we can take a group of girls and see how their puberty development plays out. >> i think a lot of us thought puberty for girls started around 11 to 12. >> that's what we used to think. >> there's a new normal now? >> yes. >> i know we talked about this prior to the show. i want to put a graphic on the screen to show people the numbers. if