A: Hey, I’m reading this really interesting article about the human body.

B: Yeah? Well, we know all about that from biology lessons.

A: No, we didn’t learn much at all at school! They’re discovering loads more things all the time.
Really amazing things! Did you know that only about one tenth of the cells in your body are really
you? The rest are bacteria.

B: What? I’m not really me?

A: No, of course you are you, but you also have millions, or trillions, of bacteria in you.

B: Eeeeuuugh!

A: No, they’re mostly really helpful. Someone did an experiment to see if animals can live without
bacteria, and he found that a lot of them died or had to have a special diet. Animals need bacteria
to digest food, you see. So we’re better off with bacteria.

B: Unless the bacteria are bad.

A: Unless they are bad, but they’re nearly all good. Oh yeah, and going back to cells, do you know
how many cells you have in your body?

B: Quite a lot, I’d say. A good few.

A: Yeah, but how many?

B: I don’t know. I’m not mathematical.

A: 7 octillion! That’s 7 plus 27 noughts.

B: I knew it was a lot.

A: OK, that’s an amazingly huge number, almost impossible to imagine. But the really weird thing is
that most of the atoms are empty space, just air or nothingness. And if you took out the empty
space, you could fit your body inside a tiny cube which measures one 500th of a centimetre on
either side. That’s a box measuring 0.002 of a centimetre on each side. You’d be much too small
to see.

B: Mmm, I can imagine that. It sounds like something that would happen in a really bad Hollywood
movie. You know, a mad scientist goes: (funny voice) ‘I’m going to extract all the air from your
body’. OK, enough facts for one day.

A: Don’t go! One last thing, did you know …

B: No.

A: Did you know that you probably have mites in your eyelashes?

B: Mites in my eyelashes? What are mites exactly anyway?

A: Yeah, they’re very small creatures, like insects, only not insects. They’re about a third of a
millimetre long, so you can’t really see them. These particular mites live in eyelashes and

B: But in mine?

A: Well, maybe not. Only about 50% of people have them, and more older people. So you might not
have any. Anyway, they’re completely harmless, they just eat dead skin.

B: Yeah, right, harmless. I really would have preferred not to know that.

A: Sorry.

B: I mean, really!

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