Religion as Parasite, Parasite as Religion

This essay won joint third prize in a competition in The Skeptic magazine.

Abstract

I. Religion as parasite

Deacon's theory of language

Similarities between language and religion

Evolutionary aspects of language and religion

Religion and language both acquired in childhood

Religious language

Different patterns of transmission

Parasites always bad?

Symbiosis in humans

Some experimenters have tested such ideas on themselves. By deliberately infecting themselves with intestinal worms they have reduced the severity of their asthma. And there is currently a plan to infect patients suffering from multiple sclerosis with hookworm, since that parasite appears to reduce the tendency to relapse in this disease.

Can religion be a beneficial parasite?

Mitochondria as parasites

Today we think of oxygen as essential to life, but it was not always so. When oxygen first appeared on the planet it was a poison for most forms of life. But certain bacteria acquired the ability to process it and make it harmless. Later, some of these bacteria were incorporated into other kinds of cells, where they eventually became, not merely useful, but essential—not just as detoxifiers but as producers of energy. That is where our mitochondria came from and why we still have them today. They are symbionts. Now we cannot do without either mitochondria or oxygen. We would die without them, and there are diseases caused by malfunction of the mitochondria.

Religions: our psychological parasites?

II. Parasites that induce religion?

Parasites influence behaviour in various animals

There is a tiny parasitic wasp in the forests of Costa Rica which uses a certain type of spider as a host for its larva. The spider normally spins an orb-type web like the kind you can see in your garden in Britain. The wasp stings the spider, paralysing it temporarily, while it lays an egg on its abdomen. After about half an hour the spider recovers and carries on with its life as if nothing had happened. But during the next two weeks the wasp larva hatches out and sucks the spider's blood, until it is ready for the next stage in its career.

The night before the larva is due to form a pupa, the spider's behaviour changes. Instead of spinning its usual spiral web, it produces something like the top of a circus tent. In this the wasp pupa hangs upside down, preparing to hatch out and continue its life cycle by infecting another unfortunate spider.

This is too bad for the spider, but you may think that you have nothing to worry about. You are a long way removed from arachnids in evolutionary terms, after all. But wait: what about mammals? May these, too, may have their behaviour modified by parasites? Almost certainly, yes.

There is a well-known single-cell parasite called toxoplasma which infects predators, such as cats. Cats get it by eating infected rats and mice, who have in turn acquired it from the soil, where it arrived via cat faeces.

Rats have an innate fear of cats, for obvious reasons; it has been selected for in evolution. When exposed to the smell of cat urine, uninfected rats show a sensible aversion to it. Not so rats infected with toxoplasma. Describing the experiments in which this altered behaviour was demonstrated, Zuk says she found that watching a video of the infected rats as they wandered into an area sprayed with cat urine 'was like seeing the heroine in a horror movie open the door to the deserted barn while the maniac with the ax lurks behind it'.

Parasites affect human behaviour too?

It seems there may be. Infected people are more accident-prone. Men who are infected are more reserved, less trusting, and more likely to break rules. Women, in contrast, are more out-going, trusting, and self-assured. It is still not clear whether these differences are due to the toxoplasma or are personality features that make certain people more liable to infection. But if toxoplamosis is indeed responsible it suggests that humans, though not the 'intended' target, can show the same personality changes as do infected rats.

It is no doubt surprising, and potentially disturbing, to think that our personality may be in part the result of our parasites. But should it be? Many factors go to make us the kinds of people we are: our genes, our upbringing, our early experiences, to name just a few. If someone is better-natured as a result of infection with a parasite, is she really any different from another person whose pleasant temperament is the product of her genes? And would we wish to 'cure' the person if eliminating their parasite made them mistrustful and unsociable?

If toxoplasmosis can make people kinder, it doesn't seem out of the question that a parasite could make them religious. This might be an unknown infection or it might even be toxoplasma itself. It would be interesting to carry out a study to see if there is a connection between a religious temperament and infection with toxoplasma. If there is, the religion-as-parasite theory would be shown to be more literally correct than anyone had supposed! Religious believers would be horrified at the thought, but it doesn't seem to be out of the question.

III. Some implications for religion

There is an evolutionary analogy for this idea. It is likely that at least some of our genes began life as viruses—parasites—and got written into our cell nuclei during evolution. But many genes don't appear to do anything. One of the most surprising discoveries in modern genetics is that the function, if any, of most of our genes is unknown. Only about 5 per cent of the human genome (the whole collection of genes that we inherit from our parents) makes proteins that are used by the organism. The other 95 per cent has no known function and has been called junk DNA, although this is no longer a very respectable scientific term, because perhaps it does have functions which we have not yet discovered. Some of these 'junk DNA' genes do make proteins, but these don't seem to do anything useful. The great majority of our DNA is designated non-coding, which means that it apparently does nothing. Perhaps religion is like this; perhaps it is hitching a ride in our brains but not contributing much, either good or bad. It is not essential to find a function for religion to explain its existence.

Like our genomes, our minds are not carefully designed instruments that function perfectly in all circumstances to give us objective truth, but rather a collection of cobbled-together parts that don't always work as we might expect. If some of the parts are really made from parasites that have take up residence in us, it is hardly surprising if their manifestations are sometimes rather difficult to understand.

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