There's only one person on my immediate team who is under thirty. Much of the company's engineering leadership is on the "ex-dec" mailing list. Let's just say that there are no 22-year-old engineers on ex-dec.
Engineers capable of working at Google != majoring in computer science.
Computer science degrees are handed out like cracker jack prizes these days.
Men graduate college at a lower rate than women, graduate high school at a lower rate, and have a lower literacy rate. What does that have to do with the specific pool of talent from which an uber engineering company like Google would pull from?