How Long Can Humans Really Live?

older woman in motorcycle gear

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A recent study found humans can live up to 150 years old under certain conditions.

Usually, when someone reaches the milestone of turning 100, it makes local headlines and might even go viral on social media — but what if that became the norm? 

Reaching 100 years of age could become a more likely scenario than you might think, especially given that humans are now living longer than ever before. Though this average has dropped over the last three years thanks to Covid-19, average life expectancy has risen from 34 years old to 77 over the past two centuries, according to the Centers for Disease Control

But there might be some ways to dramatically extend the human lifespan even further: While there have been a number of studies in recent years, one that has arguably made the most waves was published in the journal Nature Communications last May. It concluded, among other things, that humans could live up to 150 years. Yes, you read that correctly.

Still, there’s the question of whether we would want to live that long, given that some diseases like cancer become more common as we age. There are also common conditions like hearing loss, cataracts, and neck and back pain that can make getting older uncomfortable, to say the least. 

To better understand the complexities behind potentially living longer than ever before, we turned to demographer Mark Mather and Heather Whitson, M.D. of the Duke Aging Center. 

What is the average life expectancy?

Since the mid-1800s, life expectancy has been increasing by an average of six hours a day, and by the year 2100, most people are expected to live to be 82 years old. Mather says people are living longer overall now because of the general advances in living conditions and medicine. 

“Most of the improvements we’ve seen in human lifespan through the course of human history have been due to improvements in public health and standards of living,” says Mather, who’s also the associate vice president of U.S. programs at the nonprofit Population Reference Bureau. 

But more recently, there has been a consecutive decline in life expectancy — in 2020, the U.S. reported its first major drop in lifespan since World War II with an average lifespan of 77.3 years, a slight dip from the year before. And this trend doesn’t look like it’s getting any better: Last year continued to see historically unusual drops, with life expectancy hitting 76.60 across all groups, according to a new study by a group of public health experts across the country. While other factors like diabetes and drug overdoses played a role, both studies found that coronavirus was the single biggest driver behind this fall.

“Most of this catastrophic swing in life expectancy has to do either with people dying from the virus itself or secondary consequences produced by the pandemic,” author and family physician Steven Woolf, M.D. told the Washington Post

It’s unclear whether or not this decrease will continue as more people get vaccinated because, as the study notes, the drop came largely from Americans who the researchers speculate were hesitant about getting the Covid-19 shot.

Is there a hard limit on how long humans can live?

If the study in Nature Communications is anything to go by, there is a cap on how long humans can live — barring any disease or accidental injuries, scientists estimate that to be somewhere between 120 and 150 years old. And, believe it or not, they came up with this estimate by counting blood cells and footsteps. 

While certain lifestyle factors like eating healthy might not always explain how long we live, they discovered that resilience to various stressors might be the key to helping people live longer. In the study, the researchers wrote: “If you do not target the loss of resilience, any medical intervention will fail.”

Does stress have anything to do with how long you live?

It has been well-documented that chronic stress can have a negative effect on your health, but it can also shorten your life expectancy. In fact, a 2020 study from the Finnish Institute for Health and Welfare found that it can shave off at least 2.8 years.

Dr. Whitson agrees, saying longevity is all about how well the body can respond to common life stressors, such as illness or a lack of sleep. 

“Much of our longevity and successful aging depends on how we respond to stressors from the environment: So that could be anything from an infection or an injury or even a new disease,” she explains. 

What are the different types of aging? 

Even though the physical aspects of growing old, such as getting wrinkles or moving slower, often get a lot of focus, there are four types of aging: Chronological, appearance, biological, and mental. All can provide various insights into the aging process, but scientists in the Nature Communications study used biological age to predict the onset of diseases and determine humans’ maximum lifespan. 

The main distinction when it comes to biological age is that it’s used to describe how old a person seems rather than how old a person actually is, chronologically. It’s also more difficult to quantify because instead of the number of birthdays that pass, biological age points to what’s happening at a molecular and cellular level.  

“The exciting part about that is if we can figure out at the molecular level what’s happening, it opens up opportunities for drug treatments that would directly attack the aging process itself,” Dr. Whitson tells us. 

Can aging ever be reversed? 

While none of us can stop the process of growing older, scientists believe that by reducing people’s biological age, they can extend the human’s average lifespan. 

Dr. Whitson points out that lifestyle factors like diet, exercise, and sleeping habits can all make all the difference when it comes to living longer. It’s true, The Lancet medical journal reported that you can slash your mortality risk by as much as 50 percent by walking 7,000 steps a day. 

“The two main things would be physical activity and a healthy diet,” Dr. Whitson tells us. “By healthy diet, we probably have way too many carbohydrates in our normal diet, and those trigger all sorts of processes in the body that have now been associated with a poor pace of aging.”

What are some of the benefits and drawbacks of living longer?

One of the most obvious benefits of living longer is the familial aspect: It would allow generations to know their loved ones rather than a memory. For instance, Mather’s own grandmother lived to be almost 108 years old, and she got to know many of her great-grandchildren before she died. But Mather said at a certain point she started to run out of money and just being able to survive from a financial standpoint was extremely challenging. 

“We need to address not just providing medications that will keep someone alive, but making sure that they’re entering their older years healthy and with the resources that they need,” he tells us. 

Similarly, Dr. Whitson agrees that various inequities, like what we saw during the pandemic among minority populations, could become even more pronounced, and pointed out that these types of chronic stressors, such as racism “take a toll.” She also added that there’s a difference between living and living well.

“A lot of people talk about the term ‘healthspan,’ meaning we shouldn’t focus so much on extending the lifespan,” she tells us. “The focus should be on extending the healthspan, meaning how many years of healthy life you have. You wouldn’t want to extend your lifespan if it just meant that you drew out that part toward the end where people have lost functions that are important to them.”

But if medical inventions and technological breakthroughs allow scientists to slow down the process of biological aging we wouldn’t have to choose between quality or length of life. Both Peter Fedichev, the lead author of the Nature Communications study, and Dr. Whitson predict that this is feasible within the next few years.

“Pharmaceuticals are in trials right now that could potentially slow down biological aging,” Dr. Whitson tells us. “Those trials are looking at ‘old’ medicines like metformin which is a common medication for diabetes, and newer medications that work as senolytics or on other pathways. If those trials are successful, then it’s definitely conceivable that drugs could be marketed within five years as anti-aging treatments.”