Why do our bodies age? - Monica Menesini

In 1997, a French woman named Jeanne Calment

passed away after 122 years and 164 days on this Earth,

making her the oldest known person in history.

Her age was so astounding

that a millionaire pledged $1 million to anyone who could break her record.

But in reality, living to this age or beyond

is a feat that very few, maybe even no humans,

are likely to accomplish.

Human bodies just aren't built for extreme aging.

Our capacity is set at about 90 years.

But what does aging really mean

and how does it counteract the body's efforts to stay alive?

We know intuitively what it means to age.

For some, it means growing up,

while for others, it's growing old.

Yet finding a strict scientific definition of aging is a challenge.

What we can say is that aging occurs when intrinsic processes

and interactions with the environment, like sunlight,

and toxins in the air, water, and our diets,

cause changes in the structure

and function of the body's molecules and cells.

Those changes in turn drive their decline,

and subsequently, the failure of the whole organism.

The exact mechanisms of aging are poorly understood.

But recently, scientists have identified nine physiological traits,

ranging from genetic changes

to alterations in a cell's regenerative ability

that play a central role.

Firstly, as the years pass, our bodies accumulate genetic damage

in the form of DNA lesions.

These occur naturally when the body's DNA replicates,

but also in non-dividing cells.

Organelles called mitochondria are especially prone to this damage.

Mitochondria produce adenosine triphosphate,

or ATP,

the main energy source for all cellular processes,

plus mitochondria regulate many different cell activities

and play an important role in programmed cell death.

If mitochondrial function declines,