While "life expectancy" is usually defined statistically as the average number of years left at a particular age, the phrase "longevity" is occasionally used as a synonym for "life expectancy.”
However, the term "longevity" is sometimes used to refer solely to, especially long-lived people in a population.
Due to a number of causes, including decreased infant mortality, improved living standards, improved lifestyles, higher education, and improvements in healthcare and medicine, life expectancy at birth has increased significantly over the past century.
Gender, genetics, access to healthcare, cleanliness, food and nutrition, exercise, lifestyle, and crime rates are all important variables that affect life expectancy. Evidence-based research shows that genetics and lifestyle choices are the two main determinants of lifespan.
20–30% of a person's longevity is thought to be determined by genetics; the remaining percentage is determined by personal choices and modifiable environmental circumstances.
Additionally, it was shown that hereditary factors account for practically all aspects of old age and that lifestyle virtually has no bearing on health and lifespan after the age of 80.
But then why do women outlive men?
Typically, women outlive males; this was true in pre-industrial times as it is today. Smaller bodies (which put less strain on the heart), a better immune system (because testosterone works as an immunosuppressant), and a decreased propensity to participate in physically risky activities are some explanations for this.
Another theory holds that women have evolved to live longer in order to care for their grandkids and great-grandchildren.
The biological explanation for why men die younger than women is that there are almost the same numbers of men and women at reproductive ages since 105 men are born for every 100 women.
The explanation is somewhat behavioural. Men are more likely than women to smoke, and they also tend to take greater risks, which increases their chance of suffering a life-threatening injury.
But in the latter decade of the 20th century, women did exhibit a higher life expectancy in practically every human civilization, although the magnitude of the advantage varied substantially.
The longer life expectancy of women is explained by biological variations. According to scientists, oestrogen in women helps lower blood levels of dangerous cholesterol, hence preventing illnesses like heart disease.
Additionally, it's believed that women's immune systems are superior to men's.
Researchers have shown that the wealthiest and most educated people had the smallest gender disparity in life expectancy, which suggests that increasing access to good health care, a healthy diet, and other benefits can help men live longer.