We don't know why giraffe have long neck?

We don't need to tell you giraffes have a pretty notable physical feature, but what's super-interesting about their long necks is no one knows exactly why they have them. But, you were told this one in school, right? They evolved long necks so they could graze in the treetops. Unfortunately for you, your science teacher wasn't always right, and there's still a fascinating debate going about this one.

According to BBC Earth, the idea giraffes evolved their necks to become tree-grazers came from an 1809 treatise that said giraffes had stretched to graze on the treetops so much they'd stretched themselves right into long necks. Darwin simply said giraffes with long necks were more successful at surviving and reproducing until they were all that's left.

Sounds legit, but according to the zoologists who set out to debunk the theory in the 1990s, there's a huge problem with it: giraffes actually prefer eating from lower shrubs. That gave rise to another theory, one stating a long neck gave male giraffes an advantage when it came time to fight for the ladies' attentions. Necking—seen in the video—is a bizarre kind of giraffe MMA, and giraffes have been known to kill each other doing it. The bigger the male, the better the fighter, and the more successful he is at, ultimately, mating. This theory isn't widely accepted, either, and that just means we have no clue why giraffes have long necks.