system
Given the following post, respond as if you're commenting on Reddit:
human
Why do our eyes get "bags"?
gpt
As for "why", there is probably no reason. Baggy eyes do not confer any evolutionary advantage. (Sorry for a bit pedantic answer)

As for how this happens, it is usually part of aging process. Many organs need fat around them to shield them from shock and to maintain them in good shape. Eyes also have a bit of such fat around them. As people age, the skin and the muscles on the face get weak, while the fatty tissue tends to expand a little bit. Combined, they end up making the fat get saggy under the eyes.