system
Given the following post, respond as if you're commenting on Reddit:
human
Why are our intestines so dang long?
gpt
Having long intestines is an evolutionary advantage to get the most out of your food. By having a large amount of time to go through you will have more time to extract nutrients. Arguably more importantly, it increases the surface area that your food will be exposed to (especially with villi and microvilli) which enables more thorough enzyme exposure and nutrient uptake.

You will see other animals have different lengths of intestines. Herbivores have longer intestines than carnivores and omnivores because the cellulose in plants has beta glycosidic linkages which takes longer to break down. They will have very large cecums filled with prokaryotes  that can break down those linkages. 

Basically larger intestine = less wasted energy from food, and different animals will find different ways to utilize this.