| Increase in life expectancy at birth was accompanied by the emergence of a gap in favour of women which progressively |
| widened to about 6-7 years: the longevity gender gap. On the other hand, excess of disability is currently observed to the |
| detriment of women, cancelling their longevity advantage: the disability gap. Many researchers simply conclude that |
| women live longer but in poorer health than men [42, 43]. The female survival advantage can be tracked back to conception |
| with a very large ratio of male per female conception leading to the actual ratio of 105 males for 100 females at birth [44]. |
| A small longevity gap, between 1 and 3 years, in favour of women has been observed in pre-transitional societies in line |
| with studies suggesting the existence of a small female survival advantage in many species possibly due to similar genetic |
| and hormonal processes impacting on cholesterol levels and immune functions and possibly also related to parenting |
| and child rearing. In fact, the widening of the human gender gap is a very recent phenomenon, probably due to 20th |
| century social and economic transformation, benefiting apparently women more than men. The widening of the gap |
| corresponds to a transitional period between conditions when the greatest danger to life was starvation and infectious |
| diseases to modern conditions when the greatest danger is opulence and high caloric intake leading to metabolic imbalance. |
| The question then is why women can derive a greater or a faster benefit from these changes in living conditions. |
| Another question is what will be the residual gap when men will possibly have caught up with the transition [45–47]. |
| A number of biological and social factors have been put forward to explain gender-specific behaviours, habits and beliefs |
| which can lead to the observed longevity gaps. Most researchers focus only on the longevity gap and favour a simple biological |
| or social theory such as the chromosomal, hormonal, oxidative and replicative theories on the biological side, and stress-related |
| job and gender roles, smoking and risk behaviour, social constructionist and feminist theories on the social science side |
| [45, 48–50]. Only a few look for a coherent explanation working both for the longevity and the disability gaps. |
| Indeed, everything that distinguishes men and women can contribute to explain the longevity and disability gap [42]. |
| A number of these conditions have changed over time and can contribute to explain the widening of the gaps. On the other hand, |
| women have a lower level of functioning. Studies consistently show that a greater percentage of women are disabled compared to |
| men. Although it is not clear whether there are gender differences in the reporting of disability, the prevalence of total |
| disability in older women can be estimated to be approximately 50 percent higher than in men. At every level of co-morbidity |
| women have greater disability [47]. Women have been presented as the sicker gender. The use of behavioural indices |
| (bed rest, sick leave, number of contacts, health care utilisation, self reported morbidity) will confound our understanding |
| of morbidity because they actually represent how men and women cope with illness rather that representing their true |
| health status. Depression provides a good example. Despite the fact suicide rates are much higher for men than for women, |
| depression is thought of as a female problem because women are seeking more help for depression. Instead, |
| men tend to engage in private activities, including drinking and drug abuse, designed to alleviate their depression [47, 50]. |
| Several hypotheses have been raised on the biological side to explain the gender gaps [46, 51–56]. |
| But none of the basic biological factors has significantly changed through the 20th century and cannot contribute to explain |
| the widening of the gaps [45]. According to Stindl, the longevity gap could be explained by the difference in body size between |
| men and women, needing a different number of replications and then leading to a different length of telomeres. Change in body |
| size through the 20th century would explain the widening of the gaps, men being closer to their replicative limits [57]. |
| Women may also be better able to cope with overnutrition than men. Indeed, female advantage for survival may arise in |
| prosperous countries by innate ability of the female body to mobilise and transport nutrients for the benefit of the foetus |
| in pregnancy, giving them a better excretory system. In this case caloric restriction may be more efficient for males [58]. |
| On the social science side, smoking has been the main explanation for many years. According to the tobacco theory, |
| the longevity gap should continue reducing as women approach the same total smoking years as men [45]. While men |
| and women engage in different social practices to demonstrate their masculinities and femininities respectively, male beliefs |
| and behaviours undermine their health whereas female beliefs and practices reinforce their longevity. In traditional |
| Western societies, men should be independent, strong and tough, taking risks (from street violence to skydiving, |
| according to social class), refusing to acknowledge physical discomfort and need of help, and refusing positive health |
| behaviour such as using sunscreen. Moreover, health care utilization and positive health beliefs or behaviors can be |
| viewed as a form of idealized femininity [50]. |
