• Question: Why do we have two nostrils

    Asked by to Anna, Elaine, Fiona, Kevin, Darren on 17 Jun 2014. This question was also asked by .
    • Photo: Kevin O'Dell

      Kevin O'Dell answered on 17 Jun 2014:

      I would guess that it allows us to smell in stereo, in much the same way having two eyes helps us see in stereo.

      So if your ancestors were in some dense forest and they smell a very scary predator, their two nostrils would allow them work out in which direction the predator was coming from.

      At the moment I can’t see any other reason, but it must be something to do with evolution.

    • Photo: Fiona McLean

      Fiona McLean answered on 17 Jun 2014:

      This is a great question! So it is to do with airflow! Both your nostrils have different air flows: one has a fast airflow and one has a slower airflow. The nostrils actually take turns at being the slow or fast airflow nostril. This allows fast absorbing molecules in scent to be detected in the fast airflow nostril whilst giving slow absorbing scent molecules a chance to be detected in the slow airflow nostril. This means that we can detect all sorts of scent molecules whether they are big or small and allows us to smell a whole ranges of scents at the same time.!

    • Photo: Zhiming Darren Tan

      Zhiming Darren Tan answered on 19 Jun 2014:

      Wow Fiona, I didn’t know our nostrils had such interesting behaviour! I know why we have two eyes and why we have two ears and now I know why we have two nostrils. I always just thought of it as one nose, hah!

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