Aha! Now we know what caused the Ice Age!
Global Warming from excessive Highway Construction causing increased horse and oxen traffic (with the inevitable effluvia), thus exacerbating the already rampant climate change being brought about by all those cooking fires.
Civilization is the enemy of Mother Gaia!
Down with Homo Sapiens!
When did we introduce broccoli, cauliflower, cabbage.....and beans????