A new book by University of California, Santa Barbara anthropology professor Michael Gurven examines the evolutionary roots and societal meaning of aging. In “Seven Decades: How We Evolved to Live Longer,” published by Princeton University Press in 2025, Gurven argues that living into one’s seventies is not an anomaly but rather a design feature of the human species.
“That potential to live seven decades is part of our species-typical design,” said Gurven. He explains that while recent increases in life expectancy are often attributed to modern medicine and technology, the foundation for long life was set millennia ago during humanity’s hunter-gatherer era. According to Gurven, “the gains in life expectancy we’ve seen over the past century didn’t extend our maximal longevity as much as it helped ensure that many of us get to live to older age in the first place.” In high-income countries today, he notes, typical adult lifespans now reach eight or nine decades.
Gurven draws on his research with contemporary non-industrial societies such as the Tsimané people of Bolivia. These groups provide insight into how lifestyle and environment interact with human physiology. Despite having shorter average lifespans due mainly to high childhood mortality rates, individuals who survive early years can live into their seventies and eighties even without modern conveniences.
He challenges common assumptions about aging being linked solely to biological decline after reproductive years. “Most species quickly age and die when no longer able to reproduce,” Gurven said. “That makes sense from the harsh, gene-centered perspective of natural selection. Our ability to live decades beyond menopause therefore is a rare feature of our species.”
The key factor enabling humans’ extended lifespan, according to Gurven, is multigenerational cooperation—sharing food and knowledge across ages within communities. Elders take on roles such as mediators, ritual experts, healers, toolmakers and caretakers for younger generations. This cooperation increased survival chances for all group members.
“At some point in our evolutionary history, it became a better strategy to help the kids and grandkids you already have than to keep having new ones,” explained Gurven.
Gurven also explores how different cultures define being “old.” For many hunter-gatherer societies lacking precise numerical ages in their languages, old age is measured by functional capacity rather than years lived: “For those folks, you’re ‘old’ when you can’t work anymore, and you have limited mobility.” He contrasts this with industrialized societies where retirement often signals withdrawal from mainstream life despite elders retaining valuable skills and experience.
“There’s no such thing as retirement in subsistence-oriented populations,” said Gurven. He suggests there are lessons here for industrialized nations facing demographic shifts toward older populations: recognizing untapped potential among elders could improve overall quality of life.
“The implications of global aging on society are scary to think about,” he added. “But we should recognize that one of the reasons for our species’ evolutionary success was the wide range of contributions that middle-aged and older adults made to their families, communities and society.”
“For many of us, ‘old’ is a mindset, a winding down,” concluded Gurven. “If we keep learning and doing new things, and meeting new people, we avoid feeling ‘old.’”
