How long did humans live in the past? We often hear statistics about the average lifespan of people living hundreds, even thousands of years ago. Were our ancestors really dying at the age of 30 or 40, back then? To help you understand how life expectancy and life spans have changed over time, here’s a little primer on longevity throughout history.
Lifespan vs. Life Expectancy: The term life expectancy means the average lifespan of an entire population, taking into account all mortality figures for that specific group of people. Lifespan, by contrast, is a measure of the actual length of an individual’s life. While both terms seem straightforward, a lack of historical artifacts and records have made it tough for researchers to determine how life spans have evolved through history.
Life span of early man: Until fairly recently, little information existed about how long prehistoric people lived. Too few fossilized human remains made it tough for historians to estimate the demographics of any population. Anthropology professors Rachel Caspari and Sang-Hee Lee chose instead to analyze the relative ages of skeletons found in archeological digs in eastern and southern Africa, Europe, and elsewhere. Comparing the proportion of those who died young, with those who died at an older age, the team concluded that longevity only began to significantly increase (that is, past the age of 30 or so) about 30,000 years ago – quite late in the span of human evolution.
In an article published in 2011 in Scientific American, Caspari calls the shift the “evolution of grandparents”, as it marks the first time in human history that three generations might have co-existed.
Life expectancy through to 1500 A.D.: Life expectancy estimates, which describe the population as a whole, also suffer from a lack of reliable evidence gathered from these periods. In a 2010 article published in the Proceedings of the National Academy of Sciences gerontologist and evolutionary biologist Caleb Finch describes average life spans for ancient Greek and Roman times as short: in the area of 20-35 years, though he laments the numbers are based on “notoriously unrepresentative” graveyard epitaphs and samples.
Moving forward along the historic timeline, Finch lists the challenges of deducing historic life spans and causes of death in this information vacuum. As a kind of research compromise, he and other evolution experts suggest a reasonable comparison can be made with demographic data that does exist from pre-industrial Sweden (mid-18th century) and certain contemporary, small, hunter-gatherer societies in countries like Venezuela and Brazil.
Finch writes that judging by this data, the main cause of death for centuries would most certainly have been infections, whether from infectious diseases or infected wounds from accidents or fighting. Unhygienic living conditions, with little access to effective medical care, meant life expectancy was likely limited to about 35 years of age. That’s life expectancy at birth, a figure dramatically influenced by infant mortality – pegged as high as 30%. It does not mean that the average person living in say, 1200 AD, died at the age of 35. Rather, for every child that died in infancy, another person might have lived to be 70.
Early years up to the age of about 15 continued to be perilous, thanks to risks posed by disease, injuries, and accidents. People surviving this hazardous period of life could well make it into old age.
Other infectious diseases like cholera, tuberculosis and smallpox would go on to limit the longevity of the day, but none on the scale of the bubonic plague of the 14th century. The Black Death moved through Asia and Europe and wiped out as much as a third of Europe’s population, temporarily shifting life expectancy downward.
1500 - 1800 A.D. From the 1500s to around the year 1800, life expectancy throughout Europe hovered between the ages of 30 and 40.
1800 to today: Since the early 1800s, Finch writes that life expectancy at birth has doubled – in a period of only 10 or so generations! Improved health care, sanitation, immunizations, access to clean running water and better nutrition are credited with the massive jump. Though it’s hard to imagine, researcher Elaine Larson describes in The American Journal of Public Health that doctors only began regularly washing their hands before surgery in the mid-1800s. A better understanding of hygiene and the transmission of microbes has since contributed substantially to public health.
Even as recently as 1921, countries like Canada still had an infant mortality rate of about 10%, that is, 1 out of every ten babies did not survive. According to Statistics Canada, this meant a life expectancy (or, average survival) rate in that country that was higher at age one, than at birth – a condition that persisted right until the early 1980s.
Today, most industrialized countries boast life expectancy figures of more than 75 years, according to comparisons compiled by the US Central Intelligence Agency.
Life expectancy in the future? Some researchers have predicted that lifestyle factors like obesity will halt, or even reverse, the rise in life expectancy for the first time in modern history. In an article published in the New England Journal of Medicine in 2005, epidemiologists warned that in the United States –- where 2/3 of the population is overweight or obese -- obesity and its complications (like diabetes) could well reduce life expectancy at all ages in the first half of 21st century.
- Read more: How long can humans live?
In the meantime, rising life expectancy in the West brings both good and bad news: it’s nice to be living longer, but we are now more vulnerable to the types of illnesses that hit as you get older. These “age-related diseases” include coronary artery disease, certain cancers, diabetes and dementia. Still, while they can affect quantity, and quality of life, many of these conditions can be prevented or at least delayed through healthy lifestyle choices like following an anti-aging diet, maintaining a healthy weight, exercising regularly, and keeping stress hormones like cortisol at bay.
Caleb E. Finch. “Evolution of the human lifespan and diseases of aging: Roles of infection, inflammation, and nutrition.” PNAS, January 26, 2010, vol. 107, Pages 1718-1724.
Caspari, R. “The Evolution of Grandparents.” Scientific American. 2011 vol:305 iss:2 pg:44 -9.
Caspari, R and Lee SH. “Is Human Longevity a Consequence of Cultural Change or Modern Biology?” Am J Phys Anthropol(2006) 129:512-517
Country Comparison: Life Expectancy at Birth. US Central Intelligence Agency (CIA) Public Information Sheet. Accessed September 17, 2012.
E Larson. “Innovations in health care: antisepsis as a case study.”
Am J Public Health. 1989 January; 79(1): 92–99.
Griffin JP. “Changing life expectancy throughout history.” Int Pharm J 1995. 9:199–202.
Gurven, M. and Kaplan H. “Hunter-Gatherer Longevity: A Cross-Cultural Examination.” Population and Development Review. 2007. Volume 33, Issue 2, 321-365.
Health at a Glance: Disparities in Life Expectancy at Birth. Statistics Canada Public Information Sheet. Accessed Sept.13, 2012.
H. Beltra´n-Sa´nchez, E. M. Crimmins and C. E. Finch. “Early cohort mortality predicts the rate of aging in the cohort: a historical analysis.” Journal of Developmental Origins of Health and Disease, 05/2012, pp. 1 – 7.
S. Jay Olshansky, Douglas J. Passaro, Ronald C. Hershow, Jennifer Layden, Bruce A. Carnes, Jacob Brody, Leonard Hayflick, Robert N. Butler, David B. Allison, and David S. Ludwig. A “Potential Decline in Life Expectancy in the United States in the 21st Century.” N Engl J Med 2005; 352:1138-1145