Hints： cochlea fetus

I can see the muscles that make up my face, my skull, and my own brain. So, now I can take you on that journey into my ear in a way that’s never been possible before. This time we can fly straight through my eardrum. We're inside my head and at last I can show you what we’ve come here to see. On the right, it’s my eardrum again, but now we’re looking at it from the back. And attached to the middle of it is what I want to show you. It’s a bone. Though it’s towering above us, it’s actually tiny, about the size of a grain of rice. It’s the first in a chain of three bones which transfer the vibrations of my eardrum to receptors in my cochlea. They are the smallest bones in my body and they are perfectly engineered to perform their task, yet these bones will reveal how evolution has transformed us because they were once something completely different. Let me take you back even before birth, and the bones will tell us their story: a fetus in the womb, just 12 weeks old and it’s only a few centimeters long, it would fit in an eggcup.

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