Since several threads have covered some fast runners from the past, I got to thinking about Ryun and wondered something. Jim Ryun first broke 4 minutes for the mile in the summer, I think, between his junior and senior year of high school. He was born on April 29, 1947, so that would've made him 17 years and a few months old. So here's my question: Has anyone younger ever broken 4:00 for the mile? (N.B., I'm just interested in what's on the books, not starting a thread about the validity of Kenyan birth certificates.) My mind's fuzzy on this, but I think I recall that Cornelius(?) Chirchir ran some wicked fast times at the age of 17. I just read on the IAAF site that he just ran 3:34.85 indoors 1500m at the age of 19.