• Question: why do we (humans) grow?

    Asked by millyrose to Emma, Cees on 26 Jun 2012. This question was also asked by girl.
    • Photo: Emma Trantham

      Emma Trantham answered on 26 Jun 2012:

      Hmmm good question…

      Well part of the reason we need to grow is that when we are born we have to pass through our mum’s birth canal which means we have to be much smaller than she is. If we were born and then didn’t grow then our babies would have to be smaller again and their babies would be smaller still!

      The height we (humans in general) grow to has come about because we have evolved to fit our environment. So our long legs probably helped us run away a bit (when we were still out hunting and gathering and being chased by wild animals). Being bigger and taller than some animals probably helped when we caught them for our dinner. The amount of food available to us will also have had an effect on how tall we grow.

      If you are asking at a more biological level: when we are born there are gaps near the ends of our long bones (these are bones like our leg and arm bones). These gaps are filled with something called cartilage (which is also in our ears and noses) when we are little. As we grow up bone cells grow into this cartilage space, initially pushing the cartilage space away, making the bone longer. By the time we are adults the cartilage has been replaced by bone and so our bones don’t get any longer.

      Does this answer your question?