I think if you consider the outliers on the "talent" scale, such as Jim Ryun, Sebastian Coe, current record holder Hicham El Guerrouj (3:43.13) compared to the

I think if you consider the outliers on the "talent" scale, such as Jim Ryun, Sebastian Coe, current record holder Hicham El Guerrouj (3:43.13) compared to the entirety of humanity over the past few centuries, you've got to assume there have been other outliers of equal or greater "talent". So the question is, how fast can an outlier in talent run with minimal or suboptimal training? Or what kind of training can one get "by accident"? Jim Ryun [1] (along with a handful of others) ran under 4 minutes as a high-school student (a junior in Ryun's case). He didn't exactly fall out of bed and do that, but neither was he a professional having many years of training leading up to the achievement. Ryun's training was probably not optimal. Running enthusiasts often complain that his coach was a former swim coach who did not use training routines commonly recommended today. Many sports played on foot involve lots of aerobic running combined with occasional sprinting. Also consider Cliff Young [2] who claimed to have "run for two to three days straight rounding up sheep", presumably as a routine-ish part of his job. He went on to win an 875km ultra marathon. It's all speculation of course, but given all that and the fact that modern mile record is quite a bit faster than 4 minutes, I think it's plausible that a highly talented individual got enough training from work, sports, or perhaps even dedicated training to run a 4 minute mile. [1] https://en.wikipedia.org/wiki/Jim_Ryun https://en.wikipedia.org/wiki/Jim_Ryun [2] https://en.wikipedia.org/wiki/Cliff_Young_%28athlete%29 https://en.wikipedia.org/wiki/Cliff_Young_%28athlete%29