It’s all around us. News media keeps an ongoing record of accidents and mayhem that end in death. It is so dramatic and traumatic, particularly when there is a lot a mayhem.
The death inside our bodies is even more dramatic, but less reported upon. There is a common fable that every seven years we are a new person, because by that time every cell in our body has died and been replaced. I say fable because there is no real evidence for this, and at times you will hear that it is every ten years. Again, no evidence.
What is true is that death is going on every second, around the clock, inside our body. Blood cells live on the average about four months, they don’t die all at once or that would be catastrophic. At any given time, some are new, some are middle aged, and some are old. But generally each individual blood cell has a four month life span. Of course that’s only red blood cells, white blood cells live about a year.
Skin cells live about two to three weeks, and when we age the skin cells are not replacing themselves with accuracy. Apparently something gets tired, and each future copy shows the wear and tear. The real loser in this battle is the colon cells, they die off about every four days. We are not certain about the health of the replacements.
There are about 50 to 75 trillion cells in the average body, depending upon the size of the body. All the cells have different clocks, and are hopefully being replaced with brand new cells that know what they are doing. This is a helpful perspective to the process of aging and while it is attractive to think of our selves as new every seven(or ten years), it is a fable. What is true is that we are in the process of renewal every day!
Researchers have recently determined that our brain neurons are not replaced. From the time we are born the number is fixed. Except that various activities can kill off brain cells which probably isn’t a good thing when we only have a finite amount. So technically you are the same throughout your lifetime. No new brain cells.
The final fact to ponder is that our cells get the eviction notice at different rates. Our bodies generally stop moving, but our cells go on pretty much as if nothing has happened. Eventually of course they get the message, the lights are out, the trash stops being picked up, and the furnace grows cold. That’s when every cell gets on the same timetable.
It truly is a work progressing…