• Question: why do people get old

    Asked by catarinaperal to Josh on 19 Jun 2013.
    • Photo: Josh Makepeace

      Josh Makepeace answered on 19 Jun 2013:

      Hi there 🙂

      That’s a really interesting question, and something that a lot of research is looking at at the moment. It doesn’t seem to me like the question is settled, but I’ll give you a quick run down of some of the ideas.

      Getting old is essentially the accumulation of damage to the cells and organs that make up our bodies. Eventually, we all get to a point where that damage is enough that our bodies aren’t able to funciton any more, and we die.

      The question is how the damage occurs. One suggestion is that very reactive species called oxygen radicals react with your DNA and cause damage to it by pulling out bits of it. Your body has various trick for repairing this kind of damage, but over time, some slips through the defence systems. The build up of this damage over time causes loss of function.

      One of the other ideas involves changes in the way the cells in the body reproduce. When cells are reproducing, they need to replicate the DNA in the cell. On each end of the DNA are little molecules called telomeres which act like caps on the DNA to prevent it getting damaged when the cell reproduces (basically they make sure that the copied DNA is the same as the original). As you get older, your cells are reproducing more and more, and these telomeres start getting damaged, and so they don’t do their job properly anymore. That means that when the cells reproduce, they can’t copy the DNA properly, and so they don’t function normally. This means the cells start to shut down, which means your organs don’t operate how they should – that’s part of getting old.

      Since we’re starting to understand why ageing happens, scientists are trying to do experiments to slow down or stop these effects. They’ve managed to do some pretty cool experiments which have extended the lives of rats, mice, hamsters, flies, worms and more!! It’s quite incredible. Obviously it’s still a long way off making you or I live lots longer, but it’s a fascinating area of science.

      🙂

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