• Question: why do humans only have two arms and two legs?

    Asked by anonymous1 to Pete, Rebecca, SallyB, Sally, Sian on 18 Jun 2010 in Categories: . This question was also asked by aknox537.
    • Photo: Rebecca Randell

      Rebecca Randell answered on 17 Jun 2010:

      I’m not sure why we only have two arms and two legs but we have evolved from walking around on all fours (like a dog) to what we are like now.

    • Photo: Peter Styring

      Peter Styring answered on 17 Jun 2010:

      They evolved from walking on all fours to being up right (homoerectus). As the arms weren’t being used for mobility they evolved to become more dextrous, able to perform complex manipulations.

    • Photo: Sally Fenton

      Sally Fenton answered on 17 Jun 2010:

      Because that is how we evolved! All living things on earth started off as a single cell and we evolved into the complex creatures we are today! In any species..the strongest organisms survive and pass on these characteristics which helped them survive to their offspring…obviously having 2 arms and 2 legs ws a good thing in terms of survival! I think we actually started off by walking around on all 4s…so at some point it became more beneficial and functional to walk on 2 legs and use 2 of them for arms!

    • Photo: Sian Lawson

      Sian Lawson answered on 18 Jun 2010:

      We started with the same basic skeleton pattern that you see in all animals, with four legs, and became two legged to allow us to specialise our front legs into hands.

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