Science has many theories regarding why people get older and eventually die, though it is surprising to learn how much mystery remains in this exploration.

Why do people die?

It might be surprising to learn that this question, most often asked by inquisitive children, actually remains, for the most part, unanswered.

Yes, people die because they grow older and their bodily functions begin to fail. But why do people age at all? Why does the body one day decide to stop growing bigger and stronger and decide, instead, to grow weaker and frailer until eventual death?

After all, the material composition of the human body itself doesn’t age, but is rather constantly regenerating itself – skin falls off and is replaced by new skin. Cells grow old and die and are replaced by new skin. New blood is constantly being created within bone marrow.

Death is therefore not caused by the age of the actual cells in one body.

Possible Reasons for Aging

In all honesty, scientists are not entirely sure why death occurs when it does. There are many theories as to the cause of senescence (that is a fancy, scientific way of saying aging, out of which comes the word “senile”), but none of them have quite caught on enough to be considered much more valid than the others.

Some scientists believe that senescence may be caused by a mere genetic imperfection.

In essence, the hypothesis is that there are genes within the human body which specifically relate to very specific life spans – the same type of genes which cause us to grow at a certain rate, to enter into puberty at a certain time, to stop growing taller – may be similar to genes inside of us which simply tell our body, “okay, you’ve done enough for one lifetime. It’s time for you to give yourself a rest.”

And just like that, senescence begins – joints creak, bones become brittle, wrinkles appear, hair goes gray… and then death.

Other scientists believe that, in a similar sense as the genetic theory of aging, senescence may very well be simply a disease like any other, and therefore potentially curable.

If, say these scientists, we could find a way to better regulate the genes which cause aging, or to breed them out of the species entirely, we could potentially extend human lifetimes indefinitely, barring any unforeseen incidents, such as pianos falling from the sky and random power tool accidents.

For obvious reasons, this particular view has become quite controversial in recent years, as more and more scientists jump onto the “stop aging” bandwagon in the age-old search for immortality.

Free-Radicals

Another senescence theory – one which has been gaining a lot of ground and has become one of the leading theories in recent years – is called the “free radical” theory of aging.

While it may sound like a political movement intended to liberate revolutionary leaders from prison, the free radical theory is really a quite well established scientific hypothesis, revolving around natural and very well-known processes within all organic bodies.

In a sense, the free radical theory states that the process in the body which causes age and eventual death is the exact same process responsible for the explosion of dynamite or the combustion of gasoline.

Free radicals are, in essence, highly reactive atoms. That is, they are atoms with extra electrons, which simply means they desire nothing more than to find another atom to react with, because having just a single extra electron tends to make an atom rather unstable.

Because of this, large groups of free radicals can actually become a very dangerous thing. In fact, the combustibility of a compound, such as gasoline or dynamite, has a lot to do with the concentration of free radicals within the material. In a less dramatic sense, even the most basic flames in a candle or wood fire are caused by reactions of free radicals.

These little things clearly play quite a large part everyday life, especially in ways people rarely notice. They are naturally prevalent within every human being.

Reactive Oxygen Species

One particular type of oxygen-based free radical is created naturally through ordinary, everyday human metabolism.

Normally, oxygen is rather harmless, but the radical version, derived from molecules of oxygen (that is, when two oxygen atoms bond together to form a compound), forms a reactive oxygen species (ROS), which is quite radical.

According to the free radical theory of aging, these ROS might potentially move throughout the body searching for other electrons to pair with according to natural chemical laws. In doing so, they can often inadvertently attack healthy cells within the body, such as cell membranes (lipids), proteins, and even DNA. It is this process, therefore, which eventually causes us all to age.

Perhaps, say scientists, ROS is not solely responsible for the phenomenon of senescence, but the cumulative effects of their destructive process most likely play a large role in the process.

This does make sense, though it unfortunately does not leave much room for theories which might make it possible to “reverse” the aging process. After all, free radicals in the form of ROS are a perfectly natural phenomenon within the body, and the only way to stop them would be to stop the body’s metabolism altogether, which would pretty much kill the body anyway… so it’s a lose/lose situation.

So, in the long run, death is most likely a sure thing, but that doesn’t make it any less interesting.

References:

“Long Life Spans.” Reasons to Believe.

“Free Radical Cell Death Switch Identified.” Harvard Medical School.

“Scientists Identify Molecular Events that Drive Cell Senescence.”