Less than one hundred years ago, the life expectancy of a male was only 48 years and a female was 50 years. Because of the incredible advances in medicine and the improvement in living conditions, this life expectancy has increased to well into the seventies for both genders.

Many of the diseases that claimed the lives of children and young adults in past decades have now been virtually eradicated because of the mass immunization programs mounted by the public health sector. This, along with better housing and sanitation has led to a huge increase in the number of people living well into old age. Thus, there has been a great expansion in the need for geriatric care to alleviate the disease and disability attributed largely to old age.

There are a number of reasons why the life expectancy of people varies. Some of these reasons are genetic whereas others are environmental. Tobacco smoking and excessive alcohol consumption can threaten health, as can living in poor conditions. Stress can also be a factor in aging. For instance, the psychological effects of redundancy may cause a person to age more quickly than while the person remained in his or her employment.

Genetically, a person who comes from a family where most have lived to old age is also likely to enjoy longevity. This genetic heritage can also determine the aspects of good health such as a healthy heart, healthy brain, good circulation and good eyesight and hearing.

Even people who do not come from a heritage of longevity can live to old age if they look after themselves and avoid the risk factors that cause poor physical and mental health, thus accelerating the aging process. Following a healthy diet, regular exercise, drinking in moderation, cutting out smoking, and following safe practices can all help to increase potential life span.

There are other traits that run in families as well though these may not necessarily be genetic. Overweight parents often have overweight children though this is more likely to be due to the eating habits followed in the home. Similarly, children of smokers are more likely to take up smoking when they are older. These children are also more likely to suffer from bronchitis and asthma than the children of non-smokers. They are also more predisposed to the serious conditions of emphysema and cancer.

As we age, there are certain processes which cannot be avoided. This is particularly so of cell aging. As our body cells age, we are more likely to contract certain conditions because of the decline in strength and resistance to infection. Our body's also begin to show signs of 'wear and tear'. The skin loses its elasticity, thus resulting in the wrinkling we associate with old age.

As our body's cells wear out, they are replaced by a process of cell division. The only cells which don't replicate are those in the brain which cease to divide after birth.

There have been a number of theories of why women live longer than men (they have a life expectancy of five or six years longer). In ealier decades, it was believed that women suffered less stress as they didn't hold positions of high responsibility in the workplace. They also smoked far less than men. However, both of these factors have changed over the past few decades with women holding highly responsible roles and with young women smoking far more. This may, in time, cause a radical change in the average life expectancy of women.

Another theory is that female hormones contribute to the longevity of a woman's life by protecting them. However, some evidence shows that the decrease in femle sex hormones after menopause can actually contribute to a shortened lifespan. The research in this matter remains inconclusive.

Some believe that the lack of estrogen hastens the process of wrinkling and causes the vagina to lack lubrication. The amount of calcium is also reduced, thus making them more susceptible to thinning of the bones (osteoporosis) leading to more fractures and spinal curvature. This can be prevented to a certain degree by the use of hormone replacement which should only be considered in consultation with a doctor.

The role of the older person has changed over the years. They were once well respected in the community and occupied a pivotal role in the family. However, as families have become fractured and many have become geographically scattered, this role has become undermined. This can make older people feel useless and unwanted, resulting in depression which can lead to a shorter life.

The general attitude of the older person can make a great deal of difference. Rather than focusing on the negative aspect of aging, they would be better advised to look at later life as an opportunity to start life afresh and to take up new interests. It is also important for families to reconsider the needs of their older family members, making them feel more influential in shaping the lives of future generations.