Kan en människa käka hö?

We can eat grass, however grass cells contain something called cellulose, which we cant digest to get the energy we need. Cows and other mammals can eat grass because they have special bacteria living in their stomachs called symbiont bacteria. These symbionts can break the bond in cellulose for the animal its living in. That way cows can get energy from grass. We don't have any of these symbiont bacteria, so we can't digest the cellulose in grass.