As the current global life expectancy sits around 70 years, a decade longer than in 1970, noted Australian ethicist Peter Singer has examined the moral ramifications of a much more ambitious goal: overcoming the effects of aging enough to increase lifespans by hundreds of years. Despite the efforts of anti-aging groups like the SENS Foundation, mentioned by Singer, it's a purely hypothetical discussion at this point. Nonetheless, it touches on issues we face today, like the life expectancy gap between rich and poor countries and the most ethical way to live on a planet where far fewer people are born but those who are live far longer. For more on how long people are living in our current decade, The Lancet has also published a massive study of disease and mortality.