There are only two certainties in this world: birth and death. Every single living person was born from their mother and will one day die. This chapter explores the evolution of both of these natural processes. Ironically, Dr. Moalem begins this chapter with the topic of aging. Through studying the rare disease, progeria, which causes extreme accelerated aging that results in death by the age of 30, scientists discovered that the cells of people with progeria look almost identical to normal elderly people. This is significant because it indicates that the aging process is programmed into cells, not just a result of the wear and tear of living. Through further exploration, it was discovered that cells are preprogrammed to only be able to divide a certain number of times. This concept has led scientists to hypothesize why the body would, in a way, self sabotage. So far there are two generally accepted hypotheses for why the body ages and ultimately is programmed to die. First is the concept that aging and death of humans makes room for new humans to be born, accelerating the rate of evolution. Another hypothesis is that death is the elimination of individuals who have likely acquired parasites throughout their lives in order to prevent infecting younger generations.
Now that we have the demoralizing “you will get old and die” section out of the way, let’s move on to a brighter topic in evolutionary science: birth. Dr. Moalem discusses how childbirth in humans generally lasts longer and is riskier than that of other primates. This has been previously attributed to the obstetrical dilemma, or the hypothesis that selection for both bipedalism, which is accompanied by a narrowing of the pelvis, and big brains in humans resulted in a more difficult birthing process. This leads to the question of what drove evolution towards these traits that do not seem to work together? One hypothesis for bipedalism is the savanna hypothesis which states that our ancestors moved from forests to grasslands, probably due to environmental change, where there was a harder way of life. Males had to hunt for game with tools and needed to be bipedal to travel long distances quickly and scan for prey. One major problem with this hypothesis is that it only focuses on males and does not explain at all why women and children also would have evolved. Another hypothesis is the aquatic ape theory which says that our ancestors spent time both on land and in and around water, leading to the evolution of traits that benefit aquatic environments such as less hair and more fat. In this hypothesis, bipedalism evolved in order to wade deeper while still being able to breath. Dr. Moalem shows a strong preference for this hypothesis and then proceeds to make a case for water birth over contemporary birthing measures. Dr. Moalem sites studies saying that women who give birth in water experienced an easier and accelerated delivery process, probably because babies are preprogrammed for being born into an aquatic environment.