Abstract

The 20^th century brought a very dynamic development of medicine as well as other fields of science. Leonard Hay flick writes towards the end of the 20th century in his book “How and Why We Age In 1900, as many as 75 percent of US citizens did not survive sixty-five years. Today, these statistics have almost reversed: about 70 percent live more than sixty-five years. What caused such a significant increase in the average life expectancy? Hay flick explains that this should be attributed “primarily to the decline in infant mortality”[1]. Obviously this is a very important factor in raising the population’s life expectancy. Furthermore, it must be born in mind that both, life expectancy and quality of life are influenced by a whole array of environmental factors.