Every day when I take care of my 3 horses I am reminded of the halcyon days of yore. Nothing but blue sky and crystal clean air–no dust, and no diesel.
In fact horses are a big burden in urban settings. Figure it this way, 3 horses produce overnight 20 pounds of manure by my crude estimation machine. Imagine the thousands of horses required for London or New York pre auto. Thank you Henry Ford.
As for farming, the paper below says that human farming activities may have had more of an impact than generally thought.
My grandpa Hugh, an Iowa farmer, bought his first tractor, a 1936 Allis Chalmers and I drove that tractor on my dad’s farm (dad practiced medicine so he could afford a farm) in the early 60s, so pre-machine age farming is not that long ago. Recal that the Germans relied on horses for transport in WWII.