• Question: why are some people really short?

    Asked by iluvwilmas to Adam, Joanna, Louise S, Louise W, Marcus on 20 Nov 2012.
    • Photo: Marcus Wilson

      Marcus Wilson answered on 20 Nov 2012:

      Its a mixture of genetics and the environment.

      On the genetics side its due to quite a few genes and how these interact, were not really sure which ones are more important than others.
      People with Achondroplasia (Dwarfs) are the exception to this. They have a mutation in a hormone receptor that means it is always turned on. It usually stops your bones form getting tooo long, so their bones are a lot shorter.
      for environment the most important factor seems to be nutrition. Children in afreic on average rgrow far shorter than their relatives in more affluent countries because they dont get enough to eat.

    • Photo: Joanna Giles

      Joanna Giles answered on 20 Nov 2012:

      Some features of people are due to monogenic inheritance – like the colour of your eyes or the ability to curl your tongue (can you do it?!) – that means that only one gene is responsible for the visible features (or the “phenotype”). However, most traits like height and weight and intelligence are polygenic – that means that more than one gene is responsible for the overall outcome of that feature. And on top of that (like Marcus said) the environmental factors like nutrition and amount of sleep and exercise also affect the overall outcome of those traits.

      So some people are really short (not including those with genetic mutations like dwarfs) because of one or more of their genes and also the environment.

    • Photo: Adam Paige

      Adam Paige answered on 20 Nov 2012:

      One thing that makes us grow (especially during puberty) is a hormone called pituitary growth hormone. It is released from the brain and acts on lots of cells in the body making them divide into lots of new cells so that our bodies grow. Some people don’t have much of this hormone, maybe because of problems with the pituitary gland that makes it, and therefore they do not grow as much as other people.

      In contrast, Robert Wadlow had a problem that his pituitary produced too much growth hormone. He ended up being the tallest man ever known. By the age of 13 he was 7 ft 4 in (2.24 m) tall, and by the time he was fully grown he had reached 8 ft 11.1 in (2.72 m) tall.

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