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According to 2021 data from the World Health Organization, the average global life expectancy is 71.4 years—an astonishing figure when compared to the life spans of our Paleolithic ancestors. While 71.4 years might seem modest among the longest‑living mammals, it more than doubles the roughly thirty‑year average that ancient humans achieved.
Estimating the age at death for prehistoric remains is challenging, but most evidence points to infectious diseases as the primary killer—diarrheal illnesses caused by pathogens such as E. coli and Salmonella accounted for about three‑quarters of Paleolithic deaths. Only with modern advances in hygiene, medicine and public health have we effectively “staved off” these diseases, more than doubling the average human lifespan.
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Contrary to popular belief, the transition to urban civilization did not immediately boost longevity. Archaeological data from Roman‑era Egypt show an average life expectancy that had dropped into the 20s. Dense living conditions, overcrowded streets, and a lack of proper sanitation created a perfect environment for infections to spread. Water‑borne diseases such as cholera—often transmitted through polluted rivers and poorly managed sewage—were particularly lethal.
Public baths in cities like Pompeii illustrate the problem: stagnant water collected bodily fluids, providing a breeding ground for pathogens. In many cases, the nomadic lifestyle of Paleolithic hunters‑gatherers offered a better chance of reaching thirty than settling in an overcrowded city.
High infant mortality also skewed life‑expectancy figures. While the average age of 20–25 in Roman Egypt might seem low, survivors of infancy often lived into their 40s—a respectable age for the era. Nevertheless, the loss of many infants to infectious disease dragged the average down.
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By the early 19th century, human life expectancy had risen only modestly—just a decade beyond Paleolithic levels. Epidemics persisted, and cholera outbreaks in industrial cities like London were exacerbated by untreated sewage. It was not until the germ‑theory revolution that we began to see significant gains.
John Snow’s landmark work during the 1854 London cholera epidemic mapped cases to a single water pump, demonstrating the link between contaminated water and disease. His findings spurred improvements in water treatment and sewage disposal across Europe.
Louis Pasteur’s experiments on fermentation revealed the role of microorganisms in disease. His pioneering research led to the first effective cholera vaccine and laid the groundwork for modern microbiology and immunology, driving a steady rise in life expectancy that continues to this day.
