A Cellular Reflection

A Cellular Reflection

I’ve heard it said that every cell in the human body is replaced by a new one within seven years. Of course, the lifespan of different cells varies, colon cells managing only three or four days, whereas white blood cells can live for more than a year. But the idea is that, when seven years have passed, we are essentially new individuals with all of our cells having been replaced within that time. And, if we live to the allotted span of seventy years, we would be renewed ten times during that lifetime.

Naturally, it’s the brain that spoils this neat idea. Brain cells don’t get renewed. They last as long as you’re alive and, if you lose some along the way, they are gone for good. So, maybe your body never gets older than seven but your brain soldiers on for the full seventy or more. Which explains a few things about growing old.

If we ignore that unfortunate fact, however, we can imagine a scenario when it comes to cell-renewing time in the body. I don’t think each cell would be allowed to die in place before receiving its replacement. It makes more sense for the replacement to arrive early so that it can be given some instruction and updating from the retiring incumbent. Otherwise, every cell would have to become adept at its task on the job and, for instance, we’d have to learn to walk again every seven years.

Now we have a situation where the new cell arrives, the aged retiree explains the job and ensures that the newby has it right, then they swap and everything carries on as before. Meanwhile the old cell staggers to the exit door where he is given a gold watch and wished a happy retirement by the supervising cell (himself due for retirement in a couple of months but we won’t go into that). The door is opened and our geriatric hero passes through, only to be thumped on the head by a club wielded by a waiting thug of a cell. The newly-donated watch is purloined and passed back through the doorway to form the gift to the next unhappy retiree and our unconscious ex-cell is consigned to the chute that leads down to the recycling department.

It seems a bit brutal but nobody ever claimed that nature is a generous and gentle benefactor. Rather, the phrase, “red in tooth and claw” springs to mind. If survival of the fittest is the rule, then it’s a matter of keep working until you drop. Which is more ruthless than any of our corporations, whatever any class warrior may think.

I find this whole business of us being an assemblage of cells to be quite interesting. At what point did they all get together and decide to become a human being, with each cell adopting a specific purpose and adapting itself accordingly? One can understand the ambition of one to be a part of the eye and so have a clear view of the world. But the ambition of another to be in the sphincter department is less easy to comprehend.

The really sad thing is that, although such a complex and carefully designed construction of cells is able to function with awareness and purpose, the individual cells must be ignorant of everything except their own tiny part in the whole. Each has a particular job to do and does it faithfully and excellently (generally) until the end of its days but never does any cell achieve a realisation of the grand purpose of it all.

I suppose that we must be grateful that the little fellows serve with such unfailing loyalty to their tasks for, without them, all that we now know as “I” would not exist. There are, after all, plenty of cells that have retained their independence and do their own thing without regard for the gargantuan constructions that now peer at them through microscopes. Thank goodness, evolution or God that our little armies of cells signed on to be a part of us and now perform with such unswerving devotion.

I am seventy-one years old and have just been renewed, therefore. I wonder if I can haul this new bunch through seven long years to the next upgrade.


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