Why does our skin wrinkle as we get older?

Look at your hands right now. The skin is smooth, stretchy, bouncy — pull it and it snaps right back. But if you look at your grandparents' hands, you'll see something different: little lines, soft folds, skin that doesn't bounce back quite as fast. What's happening under there?
Your skin is made of layers, like a sandwich. The top layer you see is tough and waterproof. But the magic happens in the layer underneath — the dermis — where two proteins work together like a mattress and springs. Collagen is the mattress: thick, strong fibers that give your skin structure. Elastin is the springs: stretchy fibers that let your skin bounce back when you move.
