- Here are two mice, believe it or not, they're the same age.

The difference is in the treatment of their cells.

Let me explain.

Over the course of a person's life or in this case, a mouse's life, cells accumulate damage.

They react in one of three ways.

They self-correct, they die, or they retire.

These retired or zombie cells contribute heavily to the aging process.

One mouse has had these zombie cells removed, the other hasn't.

So, how does this experiment relate to us, human beings living longer, or even maybe forever.

I'm science writer, Swapna Krishna.

Let's explore the future of aging (funky music) For most of human history, the average life expectancy was 35 years.

People died young, but that all changed over the course of the 20th century in what's been called The Great Escape because of three main drivers, vaccines, germ theory, and antibiotics.

All those innovations have led to a lot more people sticking around a lot longer.

By 2050, one in six people will be over the age of 65.

We're approaching a planet of 8 billion people, and it's not because of escalating birth rates.

It's because babies and old people, just aren't dying as much as they used to.

For most of us, the last 30 years of life will be some combination of juggling chronic disease and general frailty.

That's to say at 60, 70, 80, plus, your life will look and feel a lot different than your younger years.

So, what if we could slow aging way down or just make it less horrible?

First, we need to talk about aging.

What is aging?

What's actually happening in the body?

- That's kind of a million dollar question.

And that's what everybody's trying to address.

- The general thinking is that aging is due to the buildup of damage within a person's body over time.

Remember the phrase, "dying of old age"?

Well, these days we can get more specific because older people mostly die as the result of diseases.

Things like cancer or heart disease, and aging makes you more vulnerable.

Every eight years, your chances of dying from disease, roughly double.

So, instead of trying to tackle all the diseases that kill us, scientists are going after the root cause, aging itself.

On a cellular level, one way to tackle aging is to prevent or inhibit senescence.

That's when our cells stop growing, and replicating and kind of become zombie cells.

When you're young, your immune system clears them out easily.

But as we age, - The number of senescent cells increase in our immune system.

Its function decreases.

So, you get this tipping point where you start having too many senescent cells, not enough functional immune cells.

- These senescent cells bombard nearby cells, releasing chemicals that break down connective tissue and trigger inflammation, which is the root cause of many age related diseases, like cancer, Alzheimer's and heart disease.

So, can we just get rid of those senescent cells?

In 2016, a team of scientists did just that in mice.

Senescent cells contained the protein, p16.

Scientists were able to create a drug that targets p16, specifically killing senescent cells in the process.

The mouse that received the drug was faster and stronger until the last few months before death.

Its life was about a quarter longer, and it was also healthier.

That discovery spawned a whole new chapter of research called senolytics, treatments that clean out those senescent cells.

- Everybody's jumped into this space, Google, in collaboration with Abbvie, start a company called Calico, and put billions of dollars into developing drugs for healthy aging.

That says, yes, people are believing that this is possible.

- There's a catch here though.

P16 protein is also responsible for suppressing tumors.

If we're clearing out these senescent cells regularly, it could trigger tumor and cancer growth.

We are just not sure of the long term impacts yet, but the key is preserving the good, while preventing the bad side effects.

Next, let's look at our genes, the blueprint for how our body works and ages.

There's a whole set of experiments called epigenetic engineering, basically reprogramming ourselves to be younger, so that they can do what they do best, repair our damage tissue.

- I think what people in aging are interested in is can you just take any style and just make it a young version of same cell type.

It's going to be more difficult, and I think people are hoping to actually do it in a body, especially like a human body.

But, I think it's just a really exciting thing to just see where it kind of goes - But we're missing one of the most blindingly, brilliant aging discoveries ever, healthy behaviors.

Yep.

Eat your veggies, exercise and get enough sleep.

Oh, and stop smoking and drinking.

So, where is all this leading us?

What does the future hold for aging?

For example, if you don't have the money to sign up for reprogramming yourselves, are you just going to be left out?

There are already huge gaps in life expectancy and health.

In the U.S., for example, the top 1% of earners live 10 to 15 years longer than the bottom 1%.

Researchers like Paul Robbins are looking at cheap, publicly accessible drugs and supplements that could have real effects on extending the lifespan.

But none of that has been proven yet.

On the other hand, bioethicist, like Dr. Paul Wolpe, are little more cynical.

He says that the entire enterprise of increasing lifespans is misguided.

He points out that in a capitalist society, we have to think about resources and economic strain on younger generations.

- One of the great ironies of this is that the very same Silicon Valley people who are supporting this economically, wouldn't dream of hiring a 50 year old for anything, right?

They tend to, I mean, they would hire a 17 year old before they'd hire a 50 year old.

- And if increasing our health years leads to living longer, what does that mean for a planet with finite resources that is already approaching 8 billion people?

- The goal is to really increase health span.

So, let's say we all, let's say we live until we are like 80 or 90.

Do we want to live healthy until 60?

And then the last 30 years of our life just be bedridden and be miserable, or do we want to maybe live healthy until we are 88?

And maybe the last two years, we have somewhat of a reduced quality of life - But, will living longer make us happier, maybe or maybe not.

Isn't immortality usually a super villain origin story.

(funky music) - You have the lonely elderly, it is a identified problem, nothing to do with aging research, somehow magically when people live older, that problem is supposed to disappear.

- Then, there's the issue of living a long life versus a purposeful one.

Are the two mutually exclusive?

As Data from Star Trek once said, - "Mortality gives meaning to human life, Captain."

- There are fundamental changes we'd have to make to our societies if people lived healthier lives for longer, but the human lifespan has already been increasing for centuries, and we've made the adjustments and it's clear that our elder care system needs a serious overhaul.

It's also important to take note of who would have access to these kinds of treatments, just the wealthy, presumably, which would increase already stark inequalities.

Perhaps, by focusing on health and living fulfilled lives, we can bring about a revolution in aging that will avoid long, slow declines, and instead allow people to live and die in a meaningful way.

(funky music)