Rope produced nd sod for climbing and mountaineering is tested ti UIAA standards,explained in some detail here:

http://itrsonline.org/wordpress/wp-content/uploads/2014/09/Weber-Hudson1999_ITRSPaper.pdf

It is not the stuff you buy down at the hardware store (and it ain't cheap,either). Of course in use, any rope is degraded to some extent, even with care, and sunlight and exposure to various chemicals also takes a toll. Still, when ropes fail, it is usually due to cutting; rocks become quite sharp when highly stressed ropes become in cntact with them.'

Prudent climbers retire ropes before they are seriously worn. I have used retired climbing ropes to successfully lift 1000 pound loads (mammoth fossils) with no failure. And that was after tying the rope in various knots which typically reduced the strength by about 40 per cent or so.

I wonder if this research might shed light on which types of rope construction might be better (that is stronger) when tied in various knots.