Throughout history, the biggest threat to humans has been physical harm either through

injury or infection.

So it's not surprising that our bodies have developed a bunch of internal systems that

respond once our external defenses have been breached.

One of those systems is led by a special enzyme called COX that lives in tissues throughout

our bodies.

When we get injured, the nearby COX makes a chemical that triggers the production of

lots of extra sticky platelets, which rush to stop the bleeding by clotting the wounds.

And when we get an infection, the nearby COX makes a different chemical that helps dilate

our blood vessels, so that a rush of fluid brings our tough immune cells to fight the

intruders.

But the world has changed; not only are pathogens and violence no longer our biggest threats,

but we also have other - sometimes better - ways to deal with them.

Our COX enzymes don't know that, though.

And in an ironic twist, we may be more likely to be harmed by our COX's response to perceived

threats than we are from the actual injuries and infections it's supposed to protect

us from.

That's because in the modern world, COX is often triggered into action unnecessarily,

and the ensuing response can have disastrous results.

For example, compared to our ancestors, modern humans - with our sedentary lifestyles and

fatty diets - are far more likely to build up cholesterol deposits in our blood vessels

- including the ones in our hearts and in our brains.

If one of the globs happens to break open, COX gets confused and initiates the same sticky

platelet response that it does when you actually rupture a blood vessel.

Except that this time the resulting clot can stop blood flow altogether.

If this happens near the heart, you get a heart attack.

And when this happens in the brain, the clot can cause a stroke.

And to make things even worse, those same sedentary lifestyles, fatty diets and other

modern behaviors seem to make our bodies think that we have infections in certain places

when we don't.

But COX helps flood our system with fluid and immune cells anyway.

And with no actual infection to fight, some of those excited immune cells start attacking

the body instead, which can result in autoimmune disease, depression, and even certain types

of cancers.

As a result, even as our chance of dying from injuries and infections has decreased, our

chances of dying from COX-related problems has actually increased.

We don't want to totally eliminate COX - we still want it around in case we do get a serious

injury or infection, and because it also helps protect our stomach lining.

But for certain parts of the population - like older folks with more cholesterol deposits

- it makes sense to deliberately lower COX's ability to react to any threats, real or perceived.

And it turns out that Aspirin - yep, that little pain pill in your cupboard - actually

ties up any COX it comes across, thus decreasing your chances of getting certain COX-related

problems.

Taking Aspirin regularly has some risks: by blocking COX, we're more prone to internal

bleeding and stomach ulcers.

But even so, studies show that when people over 50 with high risk of heart problems regularly

take low-dose Aspirin, they on average have reduced health care costs and longer lifespans.

For modern humans, it seems, one of the best ways to save lives is to deliberately stop

our bodies from trying to save their own lives.

This video was sponsored by the University of Minnesota, where students, faculty and

staff across all fields of study are working to solve the Grand Challenges facing society.

One of these challenges is advancing health through tailored solutions, which includes

improving our understanding of the risks and benefits of the COX enzyme.

Dr. Jeffrey Chipman, of the Department of Surgery, was part of the team that discovered

a second form of COX and changed its story.

And Dr. Russell Luepker leads the Minnesota Heart Health Program and its "Ask About Aspirin"

campaign.

Thanks University of Minnesota!