• Question: why do we have our nose where we have it and our eyes where we have it, couldn't we have nose, eyes... somewhere else e.g nose where we have our eyes eyes where we have our ears...

    Asked by juneoct2233 to Hayley, Sophie on 22 Mar 2013.
    • Photo: Hayley Evers-King

      Hayley Evers-King answered on 22 Mar 2013:

      Evolution! I imagine our ears are where they are to help with our sense of balance (one on each side) but also so that we hear things evenly from both sides to keep up aware of our environment. Our eyes are in front like most predatory animals, this gives us really good vision for hunting. Prey animals by contrast have their eyes on the sides of their heads, so that they can see a greater distance around them and keep an eye out for predators whilst they graze etc. Our nose is a not as simple a story. I imagine having it in the centre facing downwards protects it from rain and other things, so that when we run we can breathe easily. Other animals, like whales have their ‘noses’ in different places as they are adapted to different ways of living – whales for example have their blowholes (equivalent to your nose!) on top of their head, so that they can easily surface and take a breath!

    • Photo: Sophie Holles

      Sophie Holles answered on 22 Mar 2013:

      I think its all about the cues that these different sensory organs pick up.. if you notice we have pretty symmetrical faces with two nostrils, two eyes and two ears. We have two of each of these so we can detect the direction of sources of smells, sights and sounds.

      So for chemical cues (smells), they travel pretty slowly, so our nostrils don’t have to be separated by a very long distance for us to detect a difference (ie you can tell where a smell’s coming from by the time of arrival of the smell at one nostril vs the other, we’re not the best at this any more but many other animals like dogs are much more sensitive and we share the fact that our noses are central, so this maybe an evolutionary face plan we’ve just inherited).

      For eyes, the visual fields detected by each eye need to overlap so that we can see in 3D.. when the two images are merged together in our brain the slight differences between the pictures from each eye allow your brain to work out how far away an object is.. this is why its hard to meet your two index finger tips together with one eye closed! Being able to see things in perspective is really important for being an accurate hunter – how far should you throw your spear or pounce! For prey animals (like deer, horses or rabbits), its more important to see a predator coming from any angle, no matter how far away they are you should try and escape! So their eyes are more on either side of their faces and the visual fields barely overlap but they have almost 360 degree vision!

      For ears you want to be able to tell where a sound is coming from, but sound travels quite quickly so they have to be separated by as far as possible so that you can tell the difference in arrival time of sound at one ear to the other. This is why it makes sense for your ears to be on either side of your head.

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