The times were changing in the 1960s. Most radically in 1968, described in one commemorative piece as “the year that changed history”.
The article declared 1968 to have been “a year of seismic social and political change across the globe. From the burgeoning anti-Vietnam war and civil rights movements in the United States, protests and revolutions in Europe and the first comprehensive coverage of war and resultant famine in Africa. The world would never be the same again.”
But the world in 1968 was merely catching up with the world of distance running.
Distance running had experienced its seismic change three years earlier, in 1965, when three young men – Ron Clarke from suburban Melbourne, Kip Keino from high up in Kenya’s Rift Valley and Michel Jazy, the son of working-class parents in France – were the vanguard of an assault that saw every world record from 1000m to the one-hour run broken, several of them repeatedly.
Full story from IAAF: http://www.iaaf.org/news/feature/running-world-records-clarke-keino-jazy-1965