When in the Course of human events, it becomes necessary for one people to dissolve the political bands which have connected them with another, and to assume among the powers of the earth, the separate and equal station to which the Laws of Nature and of Nature's God entitle them, a decent respect to the opinions of mankind requires that they should declare the causes which impel them to the separation.
Some researchers believe that there's a limit on how many years a human being could live, the maximum being 125. Others see a world in which we have centenarians walking around with people who have lived for 500 or 1,000 years. Diseases related to aging, like dementia and heart disease, currently block us from reaching that point. Our body parts wear out from use.
Not true though. Humans lived to an average of about 30-40 years before modern medicine came around. Also, it used to be that your life span was closely related to the health of your teeth. Once you lost them you were pretty much screwed.