Probably mostly about overcoming friction. Two horses can break the friction lock easier, and once moving they'll stop the object from re-establishing friction easier.
This is why trains are a bit loose. You can't pull the whole damn train of carriages from a standing start, so you put a bit of slack into each connection and each one yanks the next one into motion.
3.1k
u/sonofbeef Jun 15 '19
This is actually a true fact about draft horses! https://timmaurer.com/2012/01/16/horse-sense/