I think that chapter 12 made an interesting argument concerning the misconceptions about the increases in life expectancy with the passing of time. Though most people believe that “modern medicine,” such as cures for diseases, has done the most for increasing longevity, this theory does not hold up in the long run. If this was true, as medicine will advance with time, life expectancy will increase at a consistent rate. However, there will be a limit to the length of human life that will cease to increase despite the advance of medicine, (which we can assume will continue for the rest of time). The authors do acknowledge the importance of some advancements, such as sanitation, food supply and vaccines, but argue that the most efficient way to increase life expectancy is to increase one’s social network.