How Long Did Early Humans Live?

Ask a search engine how long people lived in the Stone Age and you will find figures like 25, 30 or 33. It is easy to picture a world in which a 35-year-old was an elder. That picture is wrong, and the reason is arithmetic.

“Life expectancy at birth” is an average across everyone born, including those who die as babies. If half of all children die before age five and the other half live to 60, life expectancy at birth is only about 32 — even though almost nobody dies at 32.

The best living evidence: hunter-gatherers

The most reliable picture of pre-agricultural lifespans comes from studying recent foraging peoples, such as the Hadza of Tanzania, the !Kung of the Kalahari, the Aché of Paraguay and the Hiwi of Venezuela. In 2007 Michael Gurven and Hillard Kaplan pulled together demographic data from these and other groups.

Their key findings:

• Childhood was dangerous. Only about 57% of children survived to age 15, mainly because of infections, gastrointestinal illness and accidents.
• Life expectancy at birth ranged from about 21 to 37 years.
• Adulthood was different. A person reaching 15 could expect to live, on average, to their early 50s or beyond. At 45, they could expect roughly another 20 years.
• The most common age of adult death — the mode — was about 72, with a range of roughly 68 to 78 across groups.

In other words, the human lifespan — the age a healthy body can reach — was already around 70 in foraging societies. Modern medicine has mostly raised the number of people who get there.

Recent foragers are not time capsules. They live in marginal environments, often with contact-era diseases, so they are an imperfect model. But they are far better than guesswork.

How do scientists age a skeleton?

For fossils, researchers must estimate age at death from bones and teeth:

• Tooth development is very precise in children; microscopic growth lines even allow ages in days, as with the Taung Child.
• Tooth wear accumulates with age, but depends heavily on diet and grit.
• Joints and sutures — the pubic symphysis, the ear-shaped surface of the pelvis, the seams of the skull — change through adulthood.

These methods work well up to about 40–50 but tend to underestimate older adults, because changes plateau. That bias makes ancient people look younger at death than they were.

The old toothless man of Dmanisi

At Dmanisi in Georgia, about 1.8 million years ago, one early Homo individual (skull D3444 with jaw D3900) had lost all but one tooth years before death. The empty sockets had fully healed and resorbed. Chewing tough meat or roots would have been difficult without help — perhaps from food softened by others, or the use of stone tools to pound food. David Lordkipanidze’s team suggested it could be early evidence of care, although it may also reflect an adaptable diet.

Neanderthal elders

Neanderthals reached older adulthood too, and some did so despite serious injury. Shanidar 1, from Iraq, lived with a withered right arm, a crushing blow to the left side of the face that probably blinded one eye, hearing loss and a damaged leg — and survived into his 40s or later. The “Old Man” of La Chapelle-aux-Saints had lost many teeth and suffered degenerative joint disease. (See did Neanderthals bury their dead? for his grave.)

The rise of the grandparents

In 2004 Rachel Caspari and Sang-Hee Lee compared the ratio of older adults (over about 30, double the age of reproductive maturity) to younger adults in fossil samples. Among australopiths the ratio was tiny, about 0.12. It rose in early Homo, reached about 0.39 in Neanderthals, and jumped to around 2.08 in Upper Palaeolithic Homo sapiens in Europe.

Put simply, among later Ice Age modern humans, adults old enough to be grandparents outnumbered younger adults. Samples are small and preservation varies, but the shift is large. Caspari argued that more older people meant more knowledge passed across generations, larger kin networks and more hands to help raise children.

The grandmother hypothesis

Humans are unusual among primates for living long after the end of female fertility. The anthropologist Kristen Hawkes, working with the Hadza, noticed that older women were extremely productive foragers, digging tubers that young children could not access and feeding their grandchildren. That help let their daughters have children more often.

The grandmother hypothesis proposes that this help selected for longer lifespans in our lineage. It is debated, but it offers an evolutionary explanation for why humans live so long past reproduction — and why the long life our ancestors could reach is not a modern gift but an ancient inheritance.

When did life get shorter?

Ironically, the arrival of farming made many populations less healthy. Skeletons from early agricultural villages often show shorter stature, more dental decay, signs of anaemia and more infectious disease, spread by crowding and domestic animals. It took thousands of years, and in some measures until the modern era, for average health to recover to forager levels.

The bottom line

Early humans did not age faster or die at 30. They lost many of their children. Those who survived childhood often lived into their 60s and 70s, and they may have been more important to their families’ survival than any other age group.