Wednesday, 30 May 2012

Goose bumps

I think the thing I enjoyed most about writing The Universe Inside You was the chance to explore how small aspects of the human body could help explore some entertaining science. Take skin, for instance.


The outer layer of your skin is primarily the same material as your hair and nails, a protein called keratin. One of the interesting things about keratin is that it isn’t a living substance. Your outer skin, hair and nails are not alive. This means, of course that all those hair adverts claiming that a product will nourish your hair are rubbish. You can’t nourish hair, any more than you can nourish a boulder. It makes no sense. But what I find particularly interesting is the paradox of what makes you a living creature. You are, without doubt alive – yet parts of you aren’t. Many of your cells could be considered to be alive, yet on their own, they aren’t you. Where does the divide come between you and the cells that make you up? Your hair and skin are certainly part of you – but they aren’t alive.

On a more mundane level, when we take a look at our skin, we can get some insights into the development of human beings. Because when we’re cold or feel threatened we get what was called goose pimples in my youth but now seems to be better known as goose bumps.

Goose bumps are a great example of the way many of our body’s responses live in the past. What is happening when you get goose bumps is that your body is fluffing up your fur. It doesn’t realize there’s not a lot to fluff because we appear relatively hairless. (I say ‘appear’ because we have as many body hairs as a chimpanzee, but those hairs are so small and fine as to be useless as fur).

The response happens when we’re cold because fluffed up fur is better at keeping an animal warm.  When the fur is fluffed up it traps more air, and this acts as an insulating blanket, just like a woolly jumper does. Only the body hasn’t cottoned on to the fact that we don’t have a nice coat of fur – so the result is to give you chicken skin.

Similarly we get the bristling feeling of our hair standing on end when we’re scared or get an emotive memory. Once more it’s a useless ancient reaction. Many mammals fluff up their fur when threatened to look bigger and so more dangerous. (Take a dog near to a cat to see the feline version of this in all its glory. The cat will also arch its back to try to look bigger.) Apparently we used to have a similar defensive fluffing up of our coat of fur – but once again, the effect is ruined by our relatively hairlessness. We still feel the sensation of having hair stand on end, but get no benefit in added bulk.

Image from Wikipedia

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