In the so-called war on cancer, if we’re ever to know our enemies and know ourselves, we have to understand evolution. And that means not just pledging allegiance to Darwin but understanding how evolution works and all its implications. Why? In an evolutionary view of the human body, our cells are modified microbes and they retain the genetic machinery to revert to their ancestral, independent states. When that happens, we get cancer.
Cancer will still plague us whether we have chemical carcinogens in the environment or not. Time is a carcinogen.
Other writers have tackled the evolutionary biology of cancer, but I haven’t seen it expressed as succinctly and clearly as it was in the Sunday New York Times piece Why Everyone Seems to Have Cancer by George Johnson. He is author of the recent book The Cancer Chronicles. I kept saying “Thank you” out loud as I read this piece, which ran in the Sunday Review section.
It starts out with this admonition:
The rhetoric about the war on cancer implies that with enough money and determination, science might reduce cancer mortality as dramatically as it has with other leading killers — one more notch in medicine’s belt. But what, then, would we die from? Heart disease and cancer are primarily diseases of aging. Fewer people succumbing to one means more people living long enough to die from the other.
We have made great progress, especially against cancers that strike children and young people. The HPV vaccine is an enormous victory. But as Johnson reminds us, since we are mortal beings after all, medicine’s rapid progress against infectious agents and heart disease means more of us will stick around long enough to die from cancer.
Here’s the heart of the explanation of cancer’s deep evolutionary roots:
…year by year, as more failing hearts can be repaired or replaced, cancer has been slowly closing the gap.
For the oldest among us, the two killers are fighting to a draw. But there are reasons to believe that cancer will remain the most resistant. It is not so much a disease as a phenomenon, the result of a basic evolutionary compromise. As a body lives and grows, its cells are constantly dividing, copying their DNA — this vast genetic library — and bequeathing it to the daughter cells. They in turn pass it to their own progeny: copies of copies of copies. Along the way, errors inevitably occur. Some are caused by carcinogens but most are random misprints.
Over the eons, cells have developed complex mechanisms that identify and correct many of the glitches. But the process is not perfect, nor can it ever be. Mutations are the engine of evolution. Without them we never would have evolved. The trade-off is that every so often a certain combination will give an individual cell too much power. It begins to evolve independently of the rest of the body. Like a new species thriving in an ecosystem, it grows into a cancerous tumor. For that there can be no easy fix.
These microscopic rebellions have been happening for at least half a billion years, since the advent of complex multicellular life — collectives of cells that must work together, holding back, as best each can, the natural tendency to proliferate. Those that do not — the cancer cells — are doing, in a Darwinian sense, what they are supposed to do: mutating, evolving and increasing in fitness compared with their neighbors….
Everyone in medicine, health policy or medical writing should read this story. Educators should read it too – to be reminded why teaching real evolution matters.
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