As we better understand why people die, we're learning how biological and behavioral factors may partly explain why women live longer than men. Scientific advancements also impact the health of women and men differently. While women may live longer than men, they report more illnesses, more doctor visits and more hospital stays than men. This is known as the morbidity-mortality paradox i.e., women are sicker but live longer.
One theory explains that women suffer from those illnesses which are less likely to kill them. Chronic non-fatal illnesses are more common in women like migraines, arthritis and asthma. These conditions may lead to poorer health, but don't increase a woman's risk of early death.
On the other hand, men are more susceptible to health conditions that can kill them. For example, men tend to have more fat surrounding their organs (called visceral fat) and women tend to have more fat under their skin (called subcutaneous fat). Visceral fat is a risk factor for coronary heart disease, the leading underlying cause of death for men.
Biological factors to women’s longevity
Coronary heart disease, which results from a combination of biological factors and lifestyle habits, is a major reason for the difference in mortality between men and women. Other biological factors may contribute to men aging faster than women, for example, testosterone in men contributes to their generally larger bodies and deeper voices. In turn, this may accelerate the age-related changes in their bodies compared to women.
On the other side, women may have a slight advantage from protective factors connected with estrogen. Coronary heart disease has been observed as three times lower in women than in men before menopause, indicating that endogenous estrogens could have a protective effect in women.
Some common behaviors that can lead to an earlier death are more common in men. Accidental deaths, including those caused by assault, poisoning, transport accidents, falls and drownings, are particularly high among young males. Men also have a greater tendency to smoke, eat poorly and avoid exercise. These habits lead to often fatal chronic illnesses, including stroke, lung cancer, heart disease, cirrhosis of the liver, tuberculosis, prostate cancer, interpersonal violence, type 2 diabetes and are also risk factors for dementia.
Attitude towards health care
A study reveals that in cases where men and women face the same disease, men forgo available health services more often than women. For example, in countries where HIV is firmly established in the general population, men are less likely than women take an HIV test or access antiretroviral therapy. They are also more likely to die of AIDS-related chronic illnesses. Male TB patients are also less likely to seek care than female ones.
Non-communicable diseases contribute the most to life expectancy differences between men and women in high-income countries, communicable diseases, injuries and maternal conditions are the main contributors to the difference. Often, the disease and conditions that compromise health in poor countries are also preventable and treatable.
Women relate to their bodies, their health and their lives in general in a much different way than men do. To caricature, women seek beauty, men seek strength and power; thus, a woman's body remains young and healthy as long as possible, whereas a man's body must be submitted to risks and challenges from an early age. The result is that women, much more than men, are attentive to their bodies and their needs and often carry on detailed dialogs more easily with their doctors. Hence, women, being more inclined to take care of their bodies and to prolong their lives, may be better able to achieve greater profit from modern medical and social advances by practicing activities that are healthier and better protect their bodies.
Social factors to women’s longevity
The diversity in worldwide longevity indicates that the difference in mortality between the sexes is also hidden in social factors. The current range of situations actually reflects different stages of a three-part historical evolution. Women most probably have a biological advantage that allows them to live longer, but in the past in several places, the status and life conditions of women nullified this benefit. Today, given the general progress in female life conditions, women have not only regained their biological advantage, but have gone much beyond it, both because they tend to engage in fewer behaviors that are bad for health than men do and because they better profit from current advances in health care and living conditions.
Several observations also indicate that the growing excess male mortality in industrial countries could be explained by the rise of so-called "man-made diseases," which are more typically male. These include exposure to the hazards of the workplace in an industrial context, alcoholism, smoking and road accidents, which have indeed increased considerably throughout the 20th century.
Role of genes in women’s longevity
The genetic advantage of females is evident. When a mutation of one of the genes of the X chromosome occurs, females have a second X to compensate, whereas all genes of the unique X chromosome of males express themselves, even if they are deleterious. More generally, the genetic difference between the sexes is associated with a better resistance to biological aging. Female hormones and the role of women in reproduction have been linked to greater longevity. Estrogen, for example, facilitates the elimination of bad cholesterol and thus may offer some protection against heart disease; testosterone, on the other hand, has been linked to violence and risk taking. Finally, the female body has to make reserves to accommodate the needs of pregnancy and breast feeding; this ability has been associated with a greater ability to cope with overeating and eliminating excess food.
Genetically, most women have two X chromosomes, and most men have one X and one Y chromosome. X chromosomes contain hundreds of protein-encoding genes, while Y chromosomes, carry the gene that determines male traits, such as the development of testes. This gene is called "SRY." Current research has shown that, women tend to live longer than men, and many mammals show this same pattern.
No one is yet sure exactly why this is the case. The findings of several researchers reveal that the XX chromosomal pairing comprises genetic material that can extend lifespan, but only in the presence of corresponding female hormones, which the ovaries secrete.
The characteristics of the two sets of genetically female, which had identical chromosomal pairings but different sets of gonads, the researchers noticed that the XX female that had grown ovaries lived longer than their counterparts with testes. For an expanded lifespan, the woman needed to have ovaries working with XX. As long as woman had XX, they escaped early death during aging.
Normally, if one X chromosome in every cell is randomly deactivated, it ensures that, if the active X chromosome becomes damaged, the inactive X can take over. While researchers need to investigate this line of inquiry and others more closely.
Most investigators have found that long-lived individuals have little in common with one another in education, income, or profession. The similarities they do share, reflect their lifestyles like many are nonsmokers, are not obese, and cope well with stress. Also, most are women. Because of their healthy habits, these older adults are less likely to develop age-related chronic diseases, such as high blood pressure, heart disease, cancer, and diabetes, than their same-age peers.
It is estimated that about 25 percent of the variation in human life span is determined by genetics, but which genes, and how they contribute to longevity, are not clearly understood. A few of the common variations (called polymorphisms) associated with long life spans are found in the APOE, FOXO3, and CETPgenes, but they are not found in all individuals with exceptional longevity. It is likely that variants in multiple genes, some of which are unidentified, act together to contribute to a long life.
Role of Longevity genes
SIRT6 is often called the "longevity genes" because of its important role in organizing proteins and recruiting enzymes that repair broken DNA. Woman without the gene age prematurely, while woman with extra copies live longer. The researchers hypothesized that if more efficient DNA repair is required for a longer lifespan, organisms with longer lifespans may have evolved more efficient DNA repair regulators.
The researchers analyzed DNA repair in 18 rodent species with lifespans ranging from 3 years (mice) to 32 years (rats and beavers). They found that the rodents with longer lifespans also experience more efficient DNA repair because the products of their SIRT6 genes, the SIRT6 proteins, are more potent. It shows that the longevity genes, SIRT6 is not the same in every species. Instead, the gene has co-evolved with longevity, becoming more efficient so that species with a stronger SIRT6 live longer. The SIRT6 protein seems to be the dominant determinant of lifespan. It is seen that, the DNA repair works better, and at the organism level, there is an extended lifespan.
The researchers then analyzed the molecular differences between the weaker SIRT6 protein found in mice versus the stronger SIRT6 found in beavers. They identified five amino acids responsible for making the stronger SIRT6 protein, helpful in repairing DNA and better at enzyme functions. When the researchers inserted beaver and mouse SIRT6 into human cells, the beaver SIRT6 better reduced stress-induced DNA damage compared to when researchers inserted the mouse SIRT6.