Tuesday, June 14, 2011

Why Life Expectancy Increased Around the World?

After remaining fairly constant for most of human history, life expectancy (the average number of years a person can expect to live) has nearly doubled in the past century. There is little disagreement over these facts. Scholarly opinion diverges, however, as to whether these increases will continue or whether human longevity is approaching its limit.

Looking to the United States as example, it can be noticed that through the first half of the 20th century, improved nutrition and the control of infectious diseases drastically reduced child and infant mortality—developments that produced astonishing advances in life expectancy.

By 1950, penicillin and sulfa drugs had yielded the first substantial decrease in U.S. adult mortality. In the latter part of the century, continued improvements in living standards, health behaviors, and medical care also lowered mortality from chronic diseases, especially heart disease and stroke. This trend was also mirrored in all industrial nations.

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Medical Reasons for Mortality Decrease

As was mentioned earlier, the main reasons for the increased life expectancy are linked to the success of the clinical medicine, helping people to live longer and in better health. Among them:

1.       Infectious disease mortality:

* Better control of the spread of infection (sanitation, water, quarantine).
* Better personal hygiene (cleanliness, no close contact with sick persons).
* Anti‐bacterial drugs (sulfonamides, antibiotics).

2.        Cardiovascular Disease Mortality:

* Decline in tobacco smoking.
* Changes in diet, reduction in consumption of saturated fat, cholesterol.
* Better control for high blood pressure and high cholesterol levels.
 Better diagnosis and treatment of heart disease and stroke.
* More and better coronary‐care units and emergency services.

3.       Decrease in Cancer Mortality:

* Better control of infection (H. pylori, human papilloma virus, hepatitis).
* Decline in cigarette smoking.
Improved treatment (surgery, chemotherapy).
* Better screening and earlier treatment.  

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Factors influencing Life Expectancy

The main social cause of the life expectancy increase is considered income increase and all issues associated with it like ability to afford medical treatment, better housing and nutrition. That is understandable, and the related studies confirmed that people with better education, income, and social status have noticeable life expectancy advantages over those in lower socioeconomic statuses.

Principal factors that influence life expectancy are technology, education, disposable income, urbanization, inequality, healthcare, and health risks/epidemics. Basic technology consists of inventions that reach to most places in the world and permeate the developed countries. Since these inventions are usually relatively old, they are both ubiquitous and inexpensive or, if expensive, they are supplied by most governments. Advanced technology, which should also have a positive effect on life expectancy, consists of recent inventions, many of which are not widely distributed worldwide mostly due to high costs and interface issues. GDP per capita is expected, among other effects, to influence the effects of advanced technology on life expectancy.

Education is having a positive effect on life expectancy because as education increases so does the knowledge of how to lead a healthier life. This knowledge might, for example, take the form of improved nutrition or reduced exposure to various health risks, such as indoor pollution exposures.

Disposable income is positively related to life expectancy for diverse reasons. As disposable income increases people have more resources for better shelter, food, and medical care.

Urbanization might seem to have a positive effect on life expectancy because as urbanization increases so does the accessibility, other things equal, to life-extending resources such as doctors, medicine, and education. However, urbanization also exerts negative effects such as stress, pollution, and congestion (with more rapid spread of infectious disease).

As the quality of healthcare increases, so should the average life expectancy. This factor is partially reflected in income, education, and perhaps urbanization.

People engage in many risky behaviors that compromise their health status and longevity. One of the foremost health risks today is tobacco smoking, so for the countries where the tobacco smoking is more socially accepted, the negative impact on life expectancy is expected.  A second risky behavior with potentially enormous implications for life expectancy is that of unprotected sex in the presence of the AIDS virus. This variable is of particular importance in that it strikes predominantly people in the younger age groups that would not otherwise be likely to die for many years. This is in contrast to the chronic diseases of aging, such as heart disease and cancer, whose cures would not dramatically affect overall life expectancy.

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Life Expectancy per Country

Based on this observation, the countries with higher income per capita should enjoy the better longevity for its residents. General trend is obvious, but some deviation from the general trend can be seen:

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As you can see from the chart, more developed countries generally have higher life expectancies than less developed countries. However, some countries like Saudi Arabia have very high GNP per capita but don't have high life expectancies. Alternatively, there are countries, like China and Cuba, that have low GNP per capita, have reasonably high life expectancies.

Currently, microstates Monaco, Macau, San Marino, and Andorra, along with Japan have the world's highest life expectancies (89.73, 84.41, 83.01, 82.43, and 82.25, respectively).

Unfortunately, AIDS has taken its toll in Africa, Asia and even Latin America by reducing life expectancy in 34 different countries (26 of them in Africa). Africa is home to the world's lowest life expectancies with Swaziland (31.88 years), Angola (38.2 years) and Zambia (38.63 years) rounding out the bottom.

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