system
Given the following post, respond as if you're commenting on Reddit:
human
Is there a correlation between length of the digestive track in a species and it's diet?

I just had a discussion with a vegan friend who said that the length of our digestive track indicates that we evolved on a vegetarian diet, and that carnivores have a much shorter track in comparison to their overall body length.  Basically a longer relative length the more likely you are to be vegetarian.  I would appreciate any insight greatly.
gpt
Yes, ther is a correlation between lenght of the digestive tract and animal's diet. Generally, herbivores have longer intestines, because it takes longer to break down and absorb nutrients from plant cells, than it does from animal's.

EDIT: Your friend is kind of right, but not entirely. Humans seem to be secondarily omnivorous. This means, that our most recent ancestors were primarily herbivorous, but humans evolved to be able to digest meat as well, just like our more distant ancestors. And let's not forget, that large amounts of nutrients absorbed from digested meat might have allowed us to evolve those big brains we have. So without meat, your friend couldn't have evolved to be able to argue that humans evolved to be herbivores ;)