{"id":32910,"date":"2021-04-13T14:56:42","date_gmt":"2021-04-13T18:56:42","guid":{"rendered":"https:\/\/www.shortform.com\/blog\/?p=32910"},"modified":"2021-04-23T14:17:23","modified_gmt":"2021-04-23T18:17:23","slug":"human-aging","status":"publish","type":"post","link":"https:\/\/www.shortform.com\/blog\/human-aging\/","title":{"rendered":"The Human Aging Process: Why and How We Age"},"content":{"rendered":"\n

Why do humans age at the rate we do? What evolutionary factors play a role in the human aging process<\/a>?<\/p>\n\n\n\n

Human aging is an unavoidable part of life. Over time, organ systems wear out and we become more susceptible to disease and injury. Find out why this process occurs and how it came to be this way through evolution.<\/p>\n\n\n\n

Continue reading to learn about human aging.<\/p>\n\n\n\n\n\n\n\n

Why We Still Age<\/strong><\/h2>\n\n\n\n

What people call human aging is biologically termed senescence<\/strong>, the bodily deterioration accompanying age. Human organ systems tend to wear out at the same rate, on average. Maintenance and repair systems lose their efficacy, and old people become progressively more vulnerable to diseases and injuries.<\/p>\n\n\n\n

Senescence has been stable over time. Over the past centuries, the average<\/em> human lifespan has increased, but the maximum<\/em> lifespan has not. Despite all our medical advances, humans cannot live past about 115 years. <\/p>\n\n\n\n

Theoretically it would be a huge reproductive advantage to maintain health for more time – imagine humans who lived to be 300 and reproduced for 100 years. Why haven\u2019t humans evolved to live longer?<\/strong><\/p>\n\n\n\n

Promoting Reproduction First<\/h3>\n\n\n\n

Early theories suggested senescence was necessary to make room for the young. But natural selection<\/a> doesn\u2019t occur on the group level. It\u2019s also prone to exploitation by individuals who don\u2019t follow the same strategy\u2014the gene that caused individuals to reproduce rapidly and live longer would overtake the population.<\/p>\n\n\n\n

Later theories, in line with our other explanations of why genes persist, suggest that genes that promoted early survival and reproduction would be selected for, even if they cause disease later in life<\/strong>. In a Stone Age world where most people die for reasons other than old age, there wouldn\u2019t be adverse selection against senescence.<\/p>\n\n\n\n

Again, per evolutionary medicine<\/a> principles, there must be a competitive equilibrium at play – living longer must confer some compensatory fitness disadvantage, and the inverse is true. <\/strong>The balance is between faster, more aggressive mating (which may necessarily cause decreased longevity) vs. longer lifespan (which may necessarily trade off with decreased fertility).<\/p>\n\n\n\n

Here are examples of genes that confer advantages early in life but cause later disease:<\/strong><\/p>\n\n\n\n