Sharks would be much more frightening with expressive eyebrows. Think about it for a second. Picture a shark, and it’s got that blank, half-crazed default shark expression on its face, staring at you like “I’m obviously going to eat you, that’s not even worth debating.” Now picture that shark with eyebrows like a human, or even a dog, has. Suddenly its face has a world of new nuance to it. It could be looking at you like “Do you taste like mackerel?” or it could be looking at you with a hazy, distant expression, like “Did I leave that license plate in my stomach again?” And it did leave that license plate in its stomach. It doesn’t really have a choice in the matter, things that big and that metal don’t come back out until you’re dead. But it doesn’t know that; it’s a shark.
But that’s just the situations when the shark has the advantage, which is probably the most likely situation because it’s a shark, and generally speaking sharks win, but what about when the shark is at a disadvantage? Say it ate the license plate off your boat (let’s pretend boats have license plates like cars, it’s just easier that way), and you’re super angry, and you’re also, like, a scuba diving ninja, so you throw on your gear and you grab your harpoon gun that also shoots underwater shurikens, and you dive in after the thing. You corner the beast in some remote ocean cave, point the sharipooken launcher in its face and make lots of menacing bubbles because people can’t talk under water, not even in a scenario as implausible as the one we’re currently inhabiting. That shark isn’t getting any sympathy from you, not with its cold, dead eyes. But slap on a pair of corrugator supercilii, which, when expertly used, transform that bloodthirsty and cornered beast of unmitigated terror into an adorable underwater puppy dog. You’re going to hesitate, your finger is going to slip from the trigger for just a fraction of a second, and instead of a face full of sharipookens that shark is going to get a stomach full of your face.
This is all just wild speculation, of course. No scientist would ever be irresponsible enough to splice the genes responsible for Miniature Schnauzer eyebrow muscle development into the genome of a great white. But just in case they are, perhaps one of you should get working on some sort of homing sharipooken launcher. One that can be fired without ever making eye contact with the beast of unmitigated terror. Just a thought.