Slow aging and our genetic programming

Dr Merlin Thomas

Merlin Thomas is a physician and a scientist. His research laboratory is at the JDRF/ Danielle Alberti Memorial Centre for the study of Diabetes Complications at the Baker IDI Heart and Diabetes Institute in Melbourne.
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It’s all in our genes?

It is often suggested that longevity is ‘all in your genes’. Many people feel reassured if they have a relative who has lived to be a hundred years old.  Certainly, some genes have been shown to affect lifespan or predispose us to some diseases. However, less than a third of variability in human lifespan is due to inherited differences in our DNA. This is why; there will never be a genetic test for aging.

Moreover, our genes are far more plastic than a fixed DNA blueprint. As every cell respond and adapt to their environment, (epigenetic) mechanisms determine which genes are expressed. Our lifestyle, diet, activity, stress, aging and numerous other factors can impact our DNA and the way it functions.’

For example, although identical twins have exactly the same DNA they become easier to tell apart as they get older. By the time they are ready to retire, the expression of their genes may be four or five times different.

Aging as memory

Aging is really a form of memory, where our accumulated experiences and exposure are cemented within our chemistry.

Although youth is not free from harm, the likelihood of impairment becomes greater as we get older. Small accidents can therefore have more important consequences as we age due to the decline in redundancy, adaptability, reserve function and repair mechanisms.

When we look in the mirror, many of the features we identify as ‘old’ are a threshold. The time that it takes to reach this threshold is called ‘aging’ and many factors affect the speed at which this happens.  For example, aging is only one factor involved in going grey. Smoking, UV exposure, stress and other factors all shorten the time it takes for the grey to take over. This is how we can appear to get older faster. Equally, by preventing this damage, we can appear to age more slowly.

Slowing aging does not mean stopping time, but modifying the risks and stepping back from the edge so time is no longer the enemy.