Only thing I'll add to this is that Archie Manning didn't allow Peyton to play full contact football until he was 14 yrs old, he wanted him to be both physically and mentally developed to handle the rigors of that life, the results speak for themselves, correlate that into how science says dogs age and grow that would be equivalent to a two year old dog, a lot of it stands to reason if we put a little thought into it.....
If thats the case with Peyton, when he did start playing full contact i bet it was against players his own age then too and not against college or professionally types untill he too was physucally and mentally mature enough to do so and as good and mature as they were