What Causes Cancer? Lovelock Tells Us

Here, in something of a nutshell, is James Lovelock's  answer, from his book, "The Revenge of Gaia:"

About 30 per cent of us will die from cancer; few seem aware that the prime cause is breathing oxygen.   One of the great stories of Gaia's evolution is that animals are empowered by oxygen, which provides them with a huge gift of rapidly available energy -- without it they would be as sessile as a tree -- but the cost of this gift is a faster rate of death, and the cost for Gaia is our ability to commit combustion.

Wow!  Who knew?   We commit larceny, murder, voting Republican, and a gigantic array of other felonies and misdemeanors, and also we commit combustion!  But to continue with Lovelock's explanation, as found on pages 123 thru 125 of his book:

Within each of the billions of cells that make up our bodies are tiny inclusions called mitochondria; these are the power stations of our cells.  Inside these tiny particles, fuel from the food we have eaten reacts with the oxygen we have breathed in.  The output of energy from the mitochondria is a flood of molecule-sized rechargeable batteries, adenosine triphosphate (ATP) molecules, each able to power for an instant our muscles and our brains, so that we can walk and run and think.  When discharged, these molecular batteries are recharged again at the mitochondrial power houses.  For our bodies, with their billions of tiny mitochondria, the danger comes from the accidental leak of combustion products.  As oxygen reacts with the food products, unintended pollutants are formed.  These include the oxygen molecule with a negative charge called the superoxide ion, the hydroxyl radical and other highly reactive molecular species.  These destructive molecules escape from the mitochondria as toxic pollutants and also arise accidentally anywhere in the body where oxygen can react unchecked.  The omnipresence of oxygen in our bodies also greatly enhances the damage done by radiation and chemical poisons.  The fiercely reactive radical products of oxidation will attack almost any other molecule they encounter, and this is how they damage the intricate orderly internal assembly of our organs.  Almost all of this damage is repaired by an evolved set of enzymes and systems - which we could look on as the security services of oxygen-breathing life.  But inevitably some damage is done to the genetic chemicals of our cells, like DNA, which are the programs and procedures for building new cells.  Wonderfully, the damage to DNA is also repaired and there is a continuous check of its integrity.

In the course of a lifetime, unavoidably, a few of the billions of these comprehensive checks fail. From the failures to repair oxygen damage, new cells are born, with fatal or near-fatal disorders.  Most of these damaged cells commit cellular suicide using a death pill that every cell possesses called a capsase.  When this is activated it sets in course an orderly progression to dissolution.  It is a miraculous process called apoptosis.  Just imagine if each one of us, on concluding that he or she was so much more harmful than useful, began to take ourselves apart in so perfect a way that a tidy, orderly heap of spare parts for future human use was left.

Sometimes the damage done to DNA by the products of oxidation disables one of the genes that sets the instructions for cellular suicide, and when that happens a maverick cell is born and grows unchecked.  Then, after several more potentially adverse changes, a fully unrestrained cancer cell is born.  It grows and invades and eventually may kill the animal that spawned it.

This is no more than an imprecise sketch of carcinogenesis.  We still lack knowledge of the finer details, but it is enough to show how the life-giving power of oxygen has its dark side.  By the time we reach the biblical allotted span of seventy years, 30 per cent of us will have died of cancer, and for almost all of those deaths, breathing oxygen will have been the main cause.

A reader might say, with some exasperation, "This is all very interesting, but how am I to keep from breathing oxygen?"

The things that Lovelock says are based on paradoxes, and because paradoxes characterize existence, we have to keep dealing with them all the time.   So, breathing oxygen has definite dangers , though if we didn't do it we would all just be stones on the beach.   And another seeming contradiction has the Sun being one of the main forces that allow us to be here, yet Gaia has to keep working hard to protect us from the Sun, or else that uncontained, spherical, nuclear furnace blazing in the sky that we dare not even look at directly would soon wipe us out as if we and all other living things had never been here at all.