Life expectancy can be defined as the average amount of time a human being can expect to live. It is typically calculated in terms of years after birth, but it is sometimes calculated starting from other ages. Over the course of history, human life expectancy rates have increased overall. Many people believe this is due to changes in medical treatments and knowledge as well as advances in both nutrition and sanitation practices.
In the United States, the 1900s were marked by a rather low life expectancy. About half of all children born in 1900 were only expected to live to reach the age of 50. Today, life expectancy has changed dramatically, as the average person (of any sex) in the United States is expected to live to be about 77 years old. While life expectancy increases in the 20th century are often attributed to a combination of nutrition, changes in overall public health, and advances in medicine, one factor stands out among all the rest. In the 20th century, the rate of infant death in developed countries decreased dramatically.
It is worth noting that females have a longer life expectancy than males. Women are expected to live to be about 79.4 years old while men are only expected to live for about 73.6 years. The life expectancy for African Americans is also quite different. African American men have a life expectancy of about 67.2 years while African American women have an average life expectancy of about 74.7 years.
The most significant changes in life expectancy rates have been seen in wealthy parts of the world, which includes places like the United States and European countries. India has seen dramatic life expectancy increases as well, however. For example, around the middle of the 1900s, the life expectancy in India was a mere 32 years old, but by the turn of the century, it had doubled to 64 years. In nations that can be considered poor, rates today tend to be about half of those in wealthier, more technologically advanced nations. For example, in Third World countries, death rates due to diseases like AIDS have kept lifespans short.
There are some exceptions to the wealthy nation versus poorer nation rule. For example, Russia saw a decrease in life expectancy in 1999, following the fall of the Soviet Union, when rates dropped to 59.9 years for men and 72.43 years for women. In this nation, the lower lifespan was not blamed on disease, but instead may be due, in part, to increasing abuse of alcohol and drugs.
Today, obesity is a concern for many and may prove to lower the life expectancy rate over time, since it may contribute to certain diseases that can be deadly. For example, being overweight contributes to certain cancers and heart disease, and it also contributes to the development of diabetes. As such, some experts predict that rates in developed, wealthier nations will lower as the population becomes more obese.