William Mair
Ideas

What I want everyone to understand about aging.

I spend as much time explaining the science of aging as doing it: to the public, to journalists, to policy makers, and to the companies building the longevity space. These are the ideas I come back to most.

01

Life expectancy is not the rate of aging.

How long we live and how fast our bodies age are different things.

Your chronological age is how long you have been alive. Your biological age is whether your body is aging faster or slower than expected. For the first time, research lets us tell the two apart: with omics and artificial intelligence we can measure the rate of biological aging in people, and in cells, tissues and animal models in the laboratory.

That changes everything about prevention. Biological aging is now measurable and modifiable. Instead of waiting years to see whether someone develops a disease, we can measure in real time whether an intervention slows the rate at which their body ages.

02

Public health’s success gave us aging.

The twentieth-century mission was to extend life expectancy, and it worked.

In the U.S., public-health interventions have added 30 years to average life expectancy. But those gains did not come from slowing how our bodies age. They came from drastically reducing early-life mortality.

So, for the first time in our history, huge numbers of us live beyond the point our bodies can maintain function. Without effective cellular and tissue maintenance, age becomes the greatest risk factor for the majority of chronic diseases: neurodegenerative disorders, cardiovascular disease, stroke, cancer, metabolic disease and osteoporosis. Aging is a public-health pandemic.

The twenty-first-century mission is to extend healthspan: the years we live free of disease and fully functional.

Figure 1 · Healthspan

Add healthy years, not just years

Healthspan: staying healthy until late in life Health over a lifetime, from birth through middle age to old age. Typically, health declines slowly from middle age and many years are lived in poor health. The goal is to stay in full health until late in life; the difference is added healthy years. Full health Poor health BirthMiddle ageOld age Added healthy years Goal: healthy until late in life Typical: a slow decline, years lived in poor health Healthspan: staying healthy until late in life, compared with a typical slow decline Full Poor BirthMiddle ageOld age

The 20th-century mission was to extend life expectancy. The 21st-century mission is to extend healthspan.

03

Disease in old age is different.

The way we get sick when we are old is not the way we get sick when we are young.

In old age, chronic diseases rarely come alone. They arrive together, because they share a common driver: the aging process itself. Medicine treats them one at a time. But cure one disease in an older person and you have not made them healthy; you have left them with one fewer comorbidity.

Geroscience takes a different approach. It treats age as a risk factor that can be mitigated, and targets the aging process that underlies many diseases at once. The prize is a healthspan dividend: compressing the years of multiple illnesses at the end of life, which dramatically improves quality of life and reduces the burden age-related disease places on families, health systems and the economy.

Figure 2 · Comorbidity

One disease at a time, or the process behind them all?

Medicine today

Treat one disease

  • Neurodegenerative disorders
  • Cardiovascular disease
  • Stroke
  • Cancertreated
  • Metabolic disease
  • Osteoporosis

Result: one fewer comorbidity, not health.

Geroscience

Target the aging process

  • Neurodegenerative disorders
  • Cardiovascular disease
  • Stroke
  • Cancer
  • Metabolic disease
  • Osteoporosis

Result: many diseases delayed together. The healthspan dividend.

04

Your ZIP code shapes how you age.

The rate of biological aging is not the same for everyone, and the differences are not just genetic.

Studies that bring lab measures of biological aging into public health are beginning to define what speeds up or slows down how our bodies age. The factors span nutrition and metabolic health, environmental exposures and infections, stress, smoking and alcohol, and social and behavioral factors such as social integration and optimism.

This work shows that the rate of biological aging contributes greatly to inequities in health. The ZIP code you are born into, and the social inequity around you, influence the very rate at which your body ages, and so when, and how badly, you develop chronic disease.

Expanding healthspan has to happen for all communities, so that progress does not deepen existing inequities. That is why I see healthy aging as a public-health emergency, not a luxury problem.
05

What we can do now, and what is coming.

The future of geroscience and what we can do today are not in competition. They inform each other.

In the lab and in cohort studies, conserved genetic, nutritional and pharmacological interventions have slowed biological aging and increased healthspan in animals from invertebrates to mice and non-human primates. Many of these discoveries are now moving into clinical trials.

While we wait for those trials, we already know a great deal. Any intervention that promotes healthy aging acts on our biology, so it can be measured at the level of our cells. A healthy diet, an active lifestyle, sleep, social connection and a positive outlook are all part of the picture of what slows biological aging.

Top down

Understand exceptional agers

Study people who stay healthy late in life, to find mechanisms to test in the lab.

Bottom up

Discover longevity interventions

Find what slows aging in the lab, to find interventions to validate in people.

06

Cutting through the longevity noise.

Public interest in longevity has never been higher, and neither has the confusion.

The wellness space is full of products, protocols and promises, and it can be hard for anyone to tell evidence from marketing. I believe that no matter how much we invest in aging biology, nothing will get real traction unless we also change how the public and policy makers think about the problem.

That does not mean pushing biohacking or making false claims. It means helping to frame the discussion honestly, and explaining what is feasible now and what may be possible in the future. It is why I talk with journalists about hype versus hope in aging research, brief legislators on the biology of aging, and help set evidence standards as a Chief Scientific Advisor.

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Essay

Toward equity in healthy aging

The full argument: why the next public-health challenge is healthspan, and why progress must reach every community.

Read the essay