Why can cows live on grass but humans

Humans and cows have different digestive systems. Cows are ruminants, which means they have four stomachs. The first stomach, the rumen, contains bacteria that break down plant matter. The food is then regurgitated and chewed again, and then it passes to the second stomach, the reticulum. The reticulum helps to further break down the food. The food then passes to the third stomach, the omasum, which absorbs water and nutrients from the food. Finally, the food passes to the fourth stomach, the abomasum, where it is digested by enzymes.

Humans, on the other hand, are omnivores, which means that we can eat both plants and animals. We have one stomach, which is not as well-equipped to break down plant matter as a cow's stomach. As a result, we cannot eat grass and other plants as our main source of food.

In addition, humans lack the enzymes necessary to digest cellulose, which is the main component of plant cell walls. This means that we cannot get all of the nutrients that we need from plants alone. We need to eat animal products, such as meat, fish, and eggs, in order to get the nutrients that we need.