>Makes you wonder how much raw human potential has progressed

Surely raw human potential cannot have progressed very much at all in the (at most) two generations represented by the 27 years the record stood.

Granted, the population is significantly higher, so it is more statistically likely that we've produced a genuinely faster human than existed 27 years ago.

I think it's fairly well accepted that most of the records being broken now are down to tech, nutrition, and aids. Springier shoes, mechanical pacers, better 'fuels', deeper understanding of exercise periodization, etc.

Give the old record runner all of the same boosts, the same training, I can't imagine he'd be noticeably slower, perhaps within hundreths, but I'd bet within a tenth or two.