A biologist is doing research on a frog.

He puts his research subject on his desk and says "Jump".
The frog, obviously not too exited to be on a desk, jumps away.
After the biologist writes down the results, he picks up the frog and cuts off his front-left leg. He lays the frog back on the desk and says "Jump".
Again, the frog jumps. The landing is a bit off, but he jumped.
The biologist now cuts the other front leg off, and lays it back on the desk. "Jump", he says.
As scared as the frog is, he jumps again, landing on his mouth.
The biologist writes it down, picks up the frog and cuts off his right-rear leg. Again, he says "jump".
the frog jumps, although he does not come that far.
The biologist writes it down again, and cuts the last leg off the frog.
"jump" he says. the frog does nothing"JUMP" he says, harder this time. the frog still stays in place.

The biologist picks up his notebook, and writes down:

Conclusion: After cutting off all the limbs of a frog, said frog will become deaf.