Human beings are mortal. Each of us goes through the process of aging and no one expects to live forever. Average life expectancy today in the USA is about 79 years. Life expectancy in some countries is higher, and in others it is lower. The US ranks number 40 in the world in life expectancy. Modern medicine has been credited with increasing the life expectancy dramatically in the last century, but the reality is that much of this increase is attributed to decrease in infant mortality. Infant deaths greatly skewed the average length of life in the past. People who were forty-five years old didn’t expect to die within the next two years, even though the average lifespan in 1900 was 47 years.