Cattle on the alp (Photo credit: Darkroom Daze)

Grasses coevolved with ungulates (we can call them cows). About 30 million years ago due to declining temperature, humidity, and atmospheric Carbon dioxide a bunch of plants including grasses evolved a more efficient form of photosynthesis called C4. This allowed them to keep their pores open longer and suck in CO2 faster without drying out. This was a tremendous advantage and these plants proliferated. The cows were loving it of course.

Fast forward to maybe 50,000 years ago and we humans follow the herds out of Africa. First during wet oscillations we follow them into the Sahara. Then during dry intervals some of us follow them north and east out of the desert and you know the rest of the story…