• Question: why do people age?

    Asked by TheMastersED to Angela, Claire, Ian, Robert, Sarah on 12 Nov 2014.
    • Photo: Sarah Harris

      Sarah Harris answered on 12 Nov 2014:

      Ageing is ultimately due to cell death but there are lots of different theories as to why this happens. A cell biologist or molecular biologist are most likely to be investigating ageing and would be able to tell you more.

    • Photo: Ian Cade

      Ian Cade answered on 12 Nov 2014:

      Essentially everything ages.

      At the very least everything is subject to the random motion of its constituent atoms. On an everyday scale you might imagine an analogy: A piece of furniture, even though its owner looks after it very carefully, will every so often get knocked and a defect will be introduced (a scratch in the varnish perhaps). It is possible that the next random knock will simply reverse the effects of the previous one (repositioning the varnish to re-fill the scratch)…. However, this is very unlikely as there are simply many more ways to damage something than to fix it! (This is just a rewording of the second law of thermodynamics).

      But why do we age at the rate we do? (given mayflies last only 1-2 days and giant tortoises average more than a 100 years, with a maximum maybe close to 200).

      Essentially, we (the human species) live as long as we do (on average) because there is no reason to live longer. We, like every other organism have been optimised by evolution to have a maximum chance of passing on our genes, and having humans living to a maximum of 80 or so turns out to be the best option. (While the average age at death has certainly increased due to medicines and a reduction murders/wars etc, it is not true that the ‘maximum age’ of people has changed very much from prehistoric times Ramesees II was maybe 90 when he died (1303-1213BC)).

      Humans are a little strange in this respect in that we stop being fertile and having babies long before we die. This is almost certainly because grandparents are valuable to society in the form of stored wisdom and are able to help with looking after the grandchildren. I expect that people eventually die because as they wear out they eventually become a burden on society and consume more resources than they are worth…

      Sounds a bit on the cruel side? Indeed it does, but that’s what evolution is like.

    • Photo: Angela Stokes

      Angela Stokes answered on 12 Nov 2014:

      Hi theMastersED
      Sarah and Ian are both right, it is to do with cell death but there is no consensus amongst scientists about what causes ageing or why it happens yet! Perhaps this is something you might like to do in your career?

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