scrambled up a ladder to the tin roof of our house, clutching a book about the evolution of animals. I was 10 years old, and I'd just finished cooking dinner for my entire family-a task that was my daily responsibility. From my perch, I could look out at the slum where we lived in a small town in India. But that wasn't what drew me to the roof: We didn't have any lamps in our house, so I needed sunlight to read my book. I didn't know it at the time, but that study routine was my ticket to a career as a scientist.