Posts
An Overview of the Mechanisms That Cause Aging
One of the best analogies to aging I have seen to date was presented by Dr. Aubry de Grey. He likens aging to owning a car. When you first buy a car it runs better than it ever will (in most cases). Unless of course you bought your car from a used car salesman who may or may not smelled like Doritos and peppermint schnapps. Your car will last you on average 12 years. Over the course of its lifespan you may notice the older your car gets the more you will have to service it, especially near the end of it's life. This is because many parts in the car have been accumulating junk, wearing down, becoming too hard or too soft, changing their shape that alters their function, and generally accumulating wear and tear that is not repaired by the changing of fluids or parts. Even worse is that when one system starts to go bad, it speeds up the degradation of all other systems it comes in contact with forming a positive feedback loop. One part will go bad here, another there, and before you know it you will be in the taco bell drive through loading up on gorditas, when your engine explodes taking out several innocent bystanders and road signs. Well maybe not that dramatic, but you get the point.
For the purpose of this explanation, the processes of aging within humans is much the same as a the deterioration of a car. Like a car, we have systems that keep us "running". All of these systems working continuously and unison in an organism is called metabolism. The good news is that we also have systems in place to make sure that metabolism runs as smoothly as evolution has so far allowed, and (no thanks to our own advances in health care) are one of the longest lived species of mammals. The bad news is that there are chinks in our evolutionary armor and these systems get gunked up, messed up, and distorted. Also similar to a car, once one of these systems becomes less efficient, it effects other systems causing a downward spiral (positive feedback loop). This is the reason that for the first half of our lives we look and feel relatively healthy, but towards the second half, our health declines seemingly exponentially. The more messed up our systems are, the more likely it is that a part will break. When a part does break and something goes wrong in our body, this is referred to as pathology.
Why hasn't evolution taken care of this problem already?
Or: Come on evolution, get with the program!
An understandable question. Logically if we were able to pass on our genes forever, they would certainly survive much longer, so why hasn't evolution solved this problem yet? Well life outside of civilization isn't exactly easy, there is always something trying to kill you. Even primitive humans had this problem. Heck, you couldn't even pop a squat in the woods without a hungry predator eyeing your tender loins. This is a time when the leading causes of death were likely predators, disease, and starvation, and the average life expectancy was somewhere between 15 and 30. You were very lucky if you even lived long enough to contract cancer. So the simple answer is that species in mother nature's violent realm seldom live long enough to select against aging. Evolution just hasn't gotten around to it.
Stay Tuned!
So there you have it. A relatively simple explanation to why we age. I was fairly ambiguous about some things over the course of the explanation for simplicity's sake, such as my liberal use of the word "systems" when referring to metabolism, but seriously, when your systems look like this, ambiguity is best. It is widely agreed that science has boiled down the system to seven distinct causes. Those are:
- Mitochondrial Mutations
- Nuclear Mutations
- Intracellular Aggregates
- Extracellular Aggregates
- Permanent Cell Loss
- Cell Senescence
- Protein Cross Linking
My first Blog post ever! Woot!
ReplyDelete