• Question: why does humens die as they get old?

    Asked by nishamaliknm to Betul, Bridget, Ceri-Wyn, Laurel, Maria on 21 Jun 2010 in Categories: . This question was also asked by dan110, wivocricket, maddmatty, davbash.
    • Photo: Ceri-Wyn Thomas

      Ceri-Wyn Thomas answered on 18 Jun 2010:

      I guess from the point of view of population dynamics if we never died when we got older (after we’d had the chance to provide care for our offspring) then we would over-populated our habitat and have to compete too much for resources like food and water. So dying ensures that new offspring have plenty of access to resources and space. That’s one reason of many anyway!

    • Photo: Maria Pawlowska

      Maria Pawlowska answered on 18 Jun 2010:

      that’s a great question!! A lot of scientists are trying to answer that. We think it might be because our bodies simply stop working as well, and things start braking as we grow older and the more things stop working the more likely it is we will die as we get older. By why hasn’t evolution come up with a way to fix that you might ask. Well evolution only works on us until we’re able to reproduce and pass our genes on – so before we get old. There’s no selection on things that happen pass reproductive age so there was no way to select for mechanisms that will help keep us healthy pass 50 or so. Plus earlier in evolution humans and their ancestors usually died before they could get old – of illnesses or eaten by something…

    • Photo: Laurel Fogarty

      Laurel Fogarty answered on 20 Jun 2010:

      Throughout our lives we replace cells. Every time we replace cells we need to replicate the DNA held within the cells. When we are young we have long stretches of DNA at the end of genes called telomeres. Replicating DNA is a risky business and every time we do it, mistakes are made. Telomeres kind of attract the mistakes, so if a mistake in replication is made it happens in a telomere, not in a gene you need (they are very useful!).

      As this happens more and more, as we get older, the telomeres get shorter so we get more mistakes building up in genes. We can see this as changes in a person as they get old. This will eventually lead to death by old age.

      There are also some genetic factors and hormones that cause humans to get old.

    • Photo: Bridget Waller

      Bridget Waller answered on 21 Jun 2010:

      In terms of the mechanism, cells just die – we don’t really know why. One of the big questions for science!

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