system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are there lines and "cracks" on our tongue?
gpt
When it comes to bodily functions, surface area is king. That's why your lungs have millions of fibers, your colon has wrinkles and cilia, and your tongue has so many little "divots" and "cracks". 

The increased surface area that comes with a rough surface allows your tongue to fit more taste buds into the same size surface.