We looked at the available data for 37 different countries around the world and we found that there was a very strong correlation between the differences in life expectancy at age 30, and the differences in smoking prevalence rates.
Professor Les Mayhew
New research suggests that by 2030, 30 year old males will be expected to live as long as, and even to outlast, their female peers. At present, females tend to live longer than males but the findings of a study conducted by researchers at City University London’s Cass Business School suggest that life expectancy is converging at age 30.
Professor Les Mayhew and David Smith began their study using data for England and Wales, before looking at trends in other countries around the world. The researchers identified smoking prevalence reductions, lower numbers of males working in professions such as mining and better healthcare, as some of the key reasons behind the apparent convergence. However, there still exist significant differences between different countries.
I spoke to Professor Mayhew to find out more about why males are closing the gap with females in terms of life expectancy. I began by asking him whether he had expected to find convergence between male and female life expectancy before undertaking his research.
"No," he replied. "We actually started out looking at something else. We were testing a concept that we call ‘the postponement of death’, and we began looking at patterns amongst males and females. We found that in England and Wales, life expectancy between the genders was converging quite rapidly. We then went on to look at other countries and we found that patterns were extremely variable. We discovered a similar pattern in Sweden but much lower signs of convergence in France. We found hardly any convergence at all in Japan."
Professor Mayhew went on to discuss some of the reasons that he and his co-author had identified for this apparent convergence between male and female life expectancy in England and Wales. Reductions in tobacco consumption seem to be by far and away the most significant contributing factor.
"I should mention that we deliberately looked at data from age 30 upwards," Professor Mayhew explained. "Mortality is higher amongst boys than it is amongst girls, but not by very much. Also, young males tend to lead riskier lifestyles in their late teens and early 20s. By removing these effects from the data, we obtained a more representative picture of the underlying trend.
"Something that we latched onto fairly quickly was the very different levels of smoking prevalence between males and females in different countries. For example, in Japan – the longest lived country in the world – very few women smoke or have ever smoked. Japanese women are the longest lived humans on the planet. Japanese males, on the other hand, have smoking prevalence rates well above 30 per cent. As a result, the gap between male and female life expectancy has considerably expanded over a period of decades, although this expansion is now slowing down.
"We then looked at the available data for 37 different countries around the world and we found that there was a very strong correlation between the differences in life expectancy at age 30, and the differences in smoking prevalence rates.
"In England and Wales, for example, during the late 1940s, approximately 80 per cent of male adults consumed some sort of tobacco – cigarettes, pipes, cigars, etc. Far fewer women smoked tobacco so there was a pronounced gap between male and female life expectancy in the early 1950s. Slowly but surely, through all sorts of mechanisms, male smoking prevalence fell. Female smoking prevalence, on the other hand, remained at around 40 per cent and it didn’t fall anywhere near as rapidly. Gradually, this fed into life expectancy. The gap between male and female life expectancy in England and Wales at age 30 peaked around 1970. At this point it was very wide indeed at almost six years. We found that the gap began to narrow after this point. At present, roughly 20 per cent of adult males and females in England and Wales smoke, so what impact will that have on future life expectancy? We must remember that lapsed smokers and heavy smokers are still living, but once they die out – especially the males – there should be further convergence between male and female life expectancy."
I asked Professor Mayhew about the extent to which female emancipation can be said to have slowed increases in female life expectancy. As he explained, this is not an easy question to answer.
"One needs to be careful here because smoking is itself linked to lots of different factors, including female emancipation," he said. "Unpicking these issues is actually quite challenging. We didn’t specifically research whether or not female emancipation had an effect. One of the papers that we quoted in our research had found a link between female emancipation and life expectancy. I think that it’s commonly accepted that there is an connection between the two. Women have been adopting male lifestyles and consequently, some of the associated health disbenefits."
Finally, I asked Professor Mayhew whether he was confident that genetic factors do not play a significant role in gender life expectancy differences.
"Oh yes, definitely," he replied. "When you look at different countries around the world, there are very significant differences between gender life expectancies. It simply cannot be the case that these are due to genetics. Take as an example Sweden in the 1920s. Here, the gap between male and female life expectancy was tiny, at approximately six months. The special factor that applied in Sweden was that males didn’t smoke tobacco in the normal way. Instead, they ingested a product called ‘snus’; a kind of snuff. Sweden was neutral during both world wars. Smoking was very strongly associated with the armed forces during this period, so Swedish males escaped this particular habit. We think that if there any genetic differences, they are small compared to lifestyle differences."
As we are not nocturnal animals by nature, then we must benefit from sunlight, in several ways. It then follows that we can deal with sunlight - maybe we need to be more in touch with how to deal with exposure. This research shows that we do not know all the ways that we use sunlight naturally, which is probably true of other environmental factors. I will be very interested in outcomes of further research. Is there any research about sunlight and cognition?
