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Asked by kannah to Iain, Jo, Leo on 24 Jun 2010 in Categories: General. This question was also asked by sbrazlil1.
Question: why do we have two nostills and not one??? xxx
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Iain Moal answered on 24 Jun 2010:
I love this question. I don’t know the answer for sure, but I think I might have an idea. One reason could be because, if one nostril is blocked, we can still breath out of the other one. It seems that at any one time, we use one nostil more than the other. Another reason could be beacuse we inherited it from ancestors which had a much keener sense of smell, and who used two nostrils to work out which direction different smells were coming from, a bit like how we have two eyes so that we can see in 3D.
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Leo Garcia answered on 24 Jun 2010:
Great question! I would say it is because two nostrils allow you to have a sense of smell ‘direction’ – depending upon which nostril the offending smell has gone up! This could be useful from an evolutionary perspective by allowing us to locate food at a distance more easily. It also means that if one nostril is blocked, we have a spare to allow us to smell things. And, although this is a gues, I would guess that the nose dividing tissue (septum) also acts as a kind of coarse grating, to stop things like flies or small insects getting up there.
Comments
kannah commented on :
thank you ian and leo, your answers are great! xxx