Why Don't More Animals Eat Wood?

The video explores why wood, despite its high caloric content, is consumed by few animals. It explains that wood's cellulose is bound by lignin, making it hard to digest. While beavers can break wood physically, termites use microbes to digest lignin. The evolution of these microbes allowed some insects to consume wood. The video speculates on why more animals haven't adapted to eat wood and suggests that future evolution might lead to more wood-eating species.

What role does lignin play in the structure of wood?

Why might more animals not be able to utilize lignin-breaking microbes?