Nature vs Nurture

You don’t have to be a genius to realise that women tend to live longer than men. When I visit my mother in the ‘Old Folk’s Home’ it is clear that the old ladies outnumber the old fellas by a heavy margin. It is not too far from the mark to describe the home as a ‘Granny Farm’. And to be fair there is the air of vegetation amongst some of the poor inmates, er, clients. A wise man once said: “Old age is a shipwreck”. Not only is old age a shipwreck, some of the wrecks have accumulated a heavy crust of barnacles and the anchor has long since drifted away…….

So why do women, as a group, outlive men? Do men take part in riskier pursuits? Does testosterone drive us to violence? Are we more stressed? Maybe we take less care of ourselves and eat and drink less healthily than women? Are men exposed to hazardous work environments? Could it be that when we become ill we are less likely to visit a health professional? I can certainly relate to this last piece of folk wisdom, or as I like to call it: “First sign of death I’m off to the doctor”.

I think there is an element of truth in all of the above and perhaps combined they help to explain the observed discrepancy to some small degree. Also noted is that males are more prone to cancer overall, than females. And this being the case and accepting that cancer is relatively common, especially amongst the aged, it may go a long way to explain life span differences between the sexes. Many factors affect predisposition to cancer and environmental factors as mentioned previously may have their role to play. Certainly stress, testosterone and unhealthy living contribute to cancer predisposition although not as great as you might expect. Certainly not as great as finger wagging, lifestyle controlling politicians and doctors would like you to think: but that is another story, for another time.

Cancer is essentially a genetic disease and I’ve always suspected that the difference in cancer rates between the sexes may come down to genetic differences, but to date I hadn't seen any hard scientific data to back up my suspicion. Speculate no more! Researchers publishing in the prestigious, Nature Genetics, found that females have an extra copy of a gene which confers a degree of protection from cancer. The gene represents another line of defence against cells growing uncontrollably. Tis no surprise that this gene is carried on the X chromosome. Males only have one copy of the X chromosome while females have a luxurious, two. The gene in question is called a 'tumour suppresser'. If a mutation occurs which destroys its function then the affected cell is not necessarily cancerous but becomes predisposed. Generally, further mutations in other tumour suppresser genes are required to provoke the cell to become cancerous. Because women have two copies of the gene, both copies need to 'knocked out' to achieve the same mutational state of the male counterpart with one copy.

Researchers estimate that this gene may be responsible for 80% of the bias in certain cancers. Overall males carry a 20% excess of cancer burden in comparison to females. So once again an important trait in humans is mainly down to genetics and only marginally influenced by how we live our lives.

The debate concerning the extent environment and genetics differentially influence our make up as humans has become contentious; bitter and understandably carries political overtones. For instance, there is very strong evidence that our innate intelligence is mostly determined by genetics and the influence of environmental factors is marginal. Wise politicians and educators stay quiet on the issue. Scientists who talk openly about the issue are shouted down and branded as fascists. Just because society, or some aspects of it at least, do not like the findings of objective scientific endeavour doesn't mean it is not true. Science, or good science, should be indifferent to whether it is in accord with prevailing mores or political correctness. Anyone is free to disregard what they like and on whatever grounds, but let us hope Anyone never becomes a scientist.