Читать книгу Phobias: Fighting the Fear - Helen Saul - Страница 21

The idea that we are attuned to life on the African plains makes a wonderful story, but most of us do not feel much like Stone-Agers. We have adapted to many changes even in the last few decades; we are more or less at ease with cars and aeroplanes, computers, dishwashers and foreign holidays. How come our fears lag so far behind?

Can we really blame our prehistoric ancestors for our fear of snakes and spiders? Fear may be contagious but evolution demands that it is passed down for tens of thousands of years. It is asking rather a lot for fear to survive intact so long. Diseases have died out in that time, whole species have become extinct. Yet evolutionists say that our fears of heights and the dark have remained unchanged since our predecessors in the Stone Age were trying to get back to their caves at night.

Charles Darwin first introduced evolution to the public in the mid nineteenth century. Some of his basic ideas were old, even then; Charles’s grandfather, Erasmus Darwin, had been one of several advocates of the theory in the eighteenth century. Charles Darwin himself became convinced during a five-year voyage through the southern hemisphere on HMS Beagle. He watched species of animals change gradually from island to island as the boat moved south. But it was his observations in the Galapagos Islands that were critical to forming his theories. Finches and giant tortoises varied slightly but predictably from island to island and the local people could always tell where a particular bird or tortoise belonged. It seemed that all the variations of these creatures must have had a common ancestor.

It took Darwin twenty years to publish The Origin of Species, possibly in part because he anticipated and dreaded the uproar it would cause. The book is packed with examples of evolving creatures: ants and bees, horses and zebras, birds, fish and plants. Darwin defined the process of natural selection as ‘the slow and gradual accumulation of numerous, slight, yet profitable variations’. If a tiny random change in an individual gives it an advantage over other members of the species it is more likely to survive, reproduce and pass the adaptation on to its offspring. The offspring in turn are more successful than those without the adaptation and over many generations more and more of the population are born with this small advantage. In the same way, variations which give their carriers a disadvantage are eliminated.

Natural selection works to produce gradations in animals’ instincts as well as in their physical features, Darwin said. Nesting birds, for instance, have an instinctive fear of most of their enemies, strengthened by their own experience and by the sight of fear in other birds. But they are slow to develop a fear of humans. According to Darwin, large birds in highly populated countries like England are wilder than small birds because they have been persecuted by humans. In uninhabited islands, large birds have no more fear than small birds. Magpies and hooded crows are wary in England but, in Darwin’s time at least, magpies were tame in Norway as were hooded crows in Egypt.

Darwin omitted humans from his arguments in The Origin of Species, but discussed them at length in later books, The Descent of Man, 1871, and The Expression of the Emotions in Man and Animals, 1872. Expression of the Emotions set out to demonstrate that different races, and even different species, show their emotions in a remarkably similar way, implying that emotions such as fear have been conserved throughout evolution:

That the chief expressive actions, exhibited by man and by the lower animals, are now innate or inherited – that is, have not been learnt by the individual – is admitted by every one. So little has learning or imitation to do with several of them that they are from the earliest days and throughout life quite beyond our control: for instance, the relaxation of the arteries of the skin in blushing, and the increased action of the heart in anger.

Fear is one of these chief emotions:

Fear was expressed from an extremely remote period, in almost the same manner as it now is by man; namely, by trembling, the erection of the hair, cold perspiration, pallor, widely opened eyes, the relaxation of most of the muscles, and by the whole body cowering downwards or held motionless.

Or, as he says elsewhere, quoting from Papinus Statius’ Thebaid: ‘Obstupui, steteruntque comae, et vox haesit’ (‘I was astounded, my hair stood on end, and my voice choked in my throat’).

Erection of the hair is singled out for special comment because it serves no purpose in humans and may simply be a leftover from evolution.

With respect to the involuntary bristling of the hair, we have good reason to believe that in the case of animals this action, however it may have originated, serves, together with certain voluntary movements, to make them appear terrible to their enemies; and as the same involuntary and voluntary actions are performed by animals nearly related to man, we are led to believe that man has retained through inheritance a relic of them, now become useless. It is certainly a remarkable fact, that the minute unstriped muscles, by which the hairs thinly scattered over man’s almost naked body are erected, should have been preserved to the present day; and that they should still contract under the same emotions, namely, terror and rage, which cause the hairs to stand on end in the lower members of the Order to which man belongs.

Darwin therefore argued that the similarity of our and animals’ response to danger is further proof of our common ancestry. But not all emotions are so ancient. Other emotions, such as blushing through shame, shyness or excessive attention, have developed more recently, he said. Different races of people across the world all blush, but animals never do.

It does not seem possible that any animal, until its mental powers had been developed to an equal or nearly equal degree with those of man, would have closely considered and been sensitive about its own personal appearance. Therefore we may conclude that blushing originated at a very late period in the long line of our descent.

Or as Mark Twain wrote, ‘Man is the only animal that blushes. Or needs to.’

Darwin referred to innate and inherited fears, but a key problem with his argument at the time was that he could not explain how physical or emotional traits were passed down. In fact, the Moravian monk Gregor Mendel was coming up with answers even then. Mendel was working with peas and developing the idea of genetic traits conserved through generations. This is now generally accepted as the mechanism by which evolution works and the idea of genes being passed from parents to children, determining family traits and peculiarities, is a familiar one.

Genes are the template from which we develop. They influence all aspects of our physical and mental well-being, including our appearance and vulnerability to diseases, our intelligence and personality. They are not the whole story and our environment also plays its part. But genes certainly influence the development of the brain’s structure and the activity of chemical messengers involved in our experience of fear. As explored in more depth in the next chapter, our genes could programme our brains to react to danger.

Although it may have taken millions of years for the lumbering progress of natural selection to give the world its incredible diversity of species, Nesse points out that individual traits can change much more quickly. Selective breeding of dogs for their temperament, for example, takes just a handful of generations to produce puppies which are either exceptionally easygoing or frantically neurotic.

But genes may not be our only link to the Stone Age. A chain of people also exists. If we are lucky, we know our parents and their parents and we may be familiar with the two or three, possibly even four generations which preceded us. These generations in turn knew their parents and grandparents and so on back through history. The human links are continuous and it could be that we learn our behaviour from those around us, just as they learnt it from another generation. A kind of cultural rather than genetic transmission of fear could take place.

Humans have passed on information since we could paint on cave walls and tell stories. Today’s films, books and TV programmes may be efficient ways of relaying a fear of ancient threats. When a writer wants to create a threatening atmosphere, a dark night, a few large spiders and a pair of animal’s eyes usually do the trick. Many ancient threats are symbols or shortcuts to fear and the storyteller only has to mention them to create the desired mood. Cultural learning is powerful and flexible and can quickly shape attitudes in an enduring way.

The idea was proposed by psychologist Graham Davey from the University of Sussex, and he set out to test it in relation to fear of spiders. Spiders have been embroiled in European culture since the Middle Ages, when they were thought to absorb poisons and to infect any food they touched. They were seen as the forerunners of disease and death during the Great Plague (the discovery that rats’ fleas carried the disease was not made until the nineteenth century). A form of hysteria called tarantulism was even blamed on the spider and only later found to be caused by too much sun. It was not all bad for the spider – tiny ‘money spiders’ were thought to bring financial good luck and cobwebs were used in traditional medicine to bind wounds – but for hundreds of years, in the main, spiders were thought to be highly dangerous and widely feared.

This thinking was confined to Europe, so if cultural learning is responsible for fear of spiders, Davey reasoned that it should only be widespread in Europeans and their descendants. Observations back him up. In parts of Africa the spider is thought to be wise and local people clean and protect its habitat. Spiders are eaten as a delicacy in areas as diverse as Indo-China, the Caribbean, among the native North Americans and Australian aborigines. Children in Brazil often keep spiders as pets. Hindus in eastern Bengal collect spiders to release at weddings to wish the couple good luck, and in Egypt it is common to put a spider in the bed of a newly married couple.

Researchers found that the incidence of spider fear in Britain is similar to that in Holland and in the US. So far, so good. Many North Americans are descended from Europeans, so this is not unexpected. The incidence in these countries was higher than in India, as predicted. But, strangely, the incidence in Japan, where there is no particular history of spider fear, is even higher, which tends to weaken the argument.

Davey’s central point is that it takes countless generations for the biology of a population to change even slightly. Threats would have had to be extremely dangerous and common, killing people in large numbers, for fear reactions to have become biologically programmed. He says we must not ignore the costs of our reactions. Our ancestors might have been well-advised to keep away from poisonous spiders or snakes, but they had to grub through plants to get food. Too much fear of insects would have led to malnutrition if it made people reluctant to look for food. An infant starting to explore its surroundings might be at risk from strangers and suspicion might be appropriate. But strangers are also likely to help a child in trouble and over-reluctance to approach a stranger could be fatal.

Spiders and snakes may simply have had longer to become embroiled in our culture and inherited learning than modern threats. Guns and electricity outlets have not been around long enough to acquire the symbolic significance that would mark them out as objects to fear. Children may develop fears by absorbing information from the people around them, who are themselves more likely to fear snakes than guns.

Cultural transmission of fear was a bold challenge to the prevailing view that our thought processes are shaped by strong biological links with our ancient predecessors. It suggested that our fears may have nothing to do with our biology and that perhaps our primitive brain was not, after all, programmed over millions of years. It is possible that we have learned them solely through careful observation of those around us.

However, this idea has not caught on. Nobody denies the importance of learning, but some of the most exciting research work is attempting to examine the structure and activity in our brains. It seems most likely that genetic and cultural transmission of information work in tandem. We have evolved with a certain biological background which comes to life only in the context of cultural learning. The tendency to fear may be instinctive or hardwired, irrevocably programmed into us as a species. But personal experience and observation of others may be essential before we develop specific fears.

The idea of flexible learning overlying hardwired fear has been re-explored by evolutionists in recent years. They are delving into aspects of the theory and attempting to test them out in practical, modern ways.