Question

why humans can't digest grass​

Answer 1

Humans can't digest grass because we don't have those microbes to produce the enzymes we'd need to break down cellulose. ... The microbes stop breaking down cellulose at a pH of 5.5 or lower, so putting them in your stomach wouldn't give you the ability to digest grass.

Answer 2

Answer:

• There are two main problems with a grass diet. The first is that human stomachs have difficulty digesting raw leaves and grasses. Animals such as cows on the other hand have a specialized stomach with four chambers to aid in the digestion of grass (a process called rumination).
• a second problem with grass as a food source is the mastication. Your dentist would not be pleased; grass contains a lot of silica, an abrasive which quickly wears down teeth. Grazing animals have teeth that are adapted to continually grow replacing the worn tooth surfaces quickly.