Age. It’s one of the greatest defining factors of who we are. It defines when we get to start driving, when we get to vote, when we should no longer be living with our parents and when we should probably stop driving. Every aspect of our lives centers around age, and whether we like it or not, it’s a process that we can’t stop from happening. So why is it that we age at all?
While we tend to gauge the aging process externally by counting grey hairs and wrinkles, aging can be traced down to the cellular and even genomic level. The best way to picture this is to actually imagine cells as tiny people. Just like our bodies, cells get old over time and either enter senescence or die. Cellular function begins to slow down and cells become less capable of fixing themselves. This loss of function within a cell can set off a domino effect amongst other cells, sending out a signal of sorts that the aging process has begun. And just as you might have guessed, as our cells enter old age, so do we. Mitochondrial function within cells becomes impaired, stem cells fail to proliferate as effectively, and proteins within cells become more likely to misfiled which only exacerbates signs of aging.
Getting down to the genomic level, DNA also plays a massive role in the aging process. DNA is an incredible thing, it’s the reason we’re even alive. Normally, DNA has the ability to repair itself and fix any mistakes that may occur during replication. This is major, considering the fact that at any give time there are upwards of a billion cells regenerating within your body. That’s upwards of a billion chances for something to go wrong, but because the mechanisms involved in DNA repair and cell division are so efficient, everything seems to work. That is until our DNA becomes too old and too damaged to possibly be repaired. Once a cell contains DNA that has been damaged too many times, the cell either destroys itself or enters into senescence. Not only does a loss of cells contribute to aging, but cells that have entered into senescence exacerbate aging by secreting inflammatory substance that lead to age-related disease. This is one of the main reasons why cancer becomes exponentially more likely as we age, because the mechanisms within our cells aren’t as efficient at catching mistakes, leading to cancerous cells that our body fails to remove.
So what about animals that seemingly live forever, like lobsters. Well, the truth is, lobsters definitely don’t live forever, but they’re speculated to live for hundreds of years which is basically be forever to us. So what is it about lobsters that makes them age so much slower than us? Well the answer may be something that you’ve never heard of before…telomeres. Telomeres are a sequence of DNA that cap the end of our chromosomes within each and every cell. With every cell division, telomeres are cut shorter and shorter until eventually they no longer cap the chromosome which is one of the biggest causes of cell degradation and cell death. You can think of it as the bit of plastic on the end of the shoelace. Once that bit is gone, there’s nothing stopping the shoelace from fraying and ultimately becoming obsolete. This means that no matter what, over time, our telomeres reach a point of no return. They essentially set a time limit on our lives. That’s where lobsters differ. Lobsters produce a special enzyme throughout the entirety of their lives known as telomerase that acts to constantly fix the bits of the telomere that are lost with each cell division. The production of this enzyme is part of the reason why lobsters can live so much longer than we can.
The fact that lobsters live in cold environments and have generally slow metabolisms may also play a role in their long lifespans. In fact, there are handfuls of organisms that are known to live hundreds of years and just so happen to live in extremely cold environments where everything about them happens at a slower pace. And while we may not be able to live to 200 by slowing our metabolisms, research has shown that people with slower heart rates may actually live longer. And the best way to achieve a slower heart rate? Exercise! These long living organisms also tend to eat less and recent research has shown that doing the same may be a way for us to extend our own lives. In year long studies, monkeys that ate less not only lived significantly longer lives, they also had a 50% decrease in diseases such as cancer, intestinal issues, arthritis, etc. So, while there may be small actions we can take in an attempt to live longer lives, the fact is that we can’t live forever. Over time our cells reach their expiration date and begin to remind us of years gone by.