Life expectancy for humans has doubled over the last 150 years as a result of progress in medical science. Medical News Today reports on a new study that links specific advances to the historical increase in average healthy life span. "Infectious diseases cause chronic inflammation in the blood that, decades later, leads to heart attacks, strokes and cancers – the classic killers of old age ... chronic infections from childhood onward accelerated vascular and other diseases." Suffering chronic disease during childhood - a common state of affairs in past decades - damages your body and thus reduces your chance of a longer, healthier life. This makes perfect sense if you consider the reliability theory of aging.