Joseph Coughlin has been director of the MIT AgeLab ever since he founded it in 1999. In his new book, The Longevity Economy, he contends that old age—much like childhood, adolescence, and gender—is a social construct, and a modern one at that.
Coughlin argues that the invention of this construct is a matter of the changing impact of pathogens. Infectious diseases had been indiscriminately killing people of all ages since populations concentrated in cities during the Neolithic Revolution 10,000 years ago. But once the germ theory of disease took hold in the late 19th century, public health initiatives improved hygiene. When antibiotics were discovered and exploited, humans were able to conquer these killers for the first time.
As modern medicine continued to improve, it was able to combat more and more conditions that had historically killed people before their prime (like cuts and childbirth). The only thing medicine couldn’t cure was age. Now that pathogens' impact is limited, the only people who routinely die are the elderly.