Positive Health Online

About 10,000 years ago, something amazing happened. After a couple of million years during which the development of homo erectus and homo neanderthalensis had proceeded at a glacial rate of change, suddenly life transformed. The human brain became bigger; music, art and religion started to emerge, and discrete cultures developed. What was it that enabled man who for over a million years had in most ways resembled every other man, (all of them even using the same sorts of hand axes the world over), suddenly to become individual and creative? There have been many theories, including the challenge of the environment, the rise of the hunter and the development of the first settled home bases, put forward to explain this mystery.

To David Horrobin, a fellow of Magdalen College where he taught medicine, and an expert in schizophrenia during a long and distinguished career, such theories lack an actual mechanism to explain why such massive changes happened. Environmental pressures weren’t unique to humans or even primates: all species could benefit from increased brain power. He proposes instead that small genetic changes in the biochemistry of brain fat were sufficient to alter the way our nerve cells worked, vastly increasing the abilities of the brain. But, as we further changed our diet and our way of life, those very genetic changes which enabled creativity, intellectual prowess and the generation of religious belief could also instigate the madness of schizophrenia.

And so begins a fascinating journey as Horrobin takes the reader through the life and times of pre-historic man to fill out what might at first seem to be a preposterous case. His writing is a delight and his ability to generate images in the mind quite masterful. Not messianic in the telling, his story stimulates and provokes considerable thought.

Fat, he claims, is what separates us from the apes. We have lots; they have little. The non-water content of the brain is 60 per cent fat. The hunger for fat is evident in all descriptions of hunter-gatherer societies. Even chimpanzees, which are essentially vegetarian, may catch monkeys, crack open the skull and eat the brain. In celebrated experiments on mice, genetic alteration of fatty acids called phospholipases led to the creation of super-mice, which were 50 per cent more intelligent than normal mice. Fat, it would appear, is highly significant.

Horrobin suggests that, far from hunting on dry savanna, at some point humans started to live by the margins of lakes and rivers. (We couldn’t have survived long on the savanna, he says, because as a species we are so profligate with water, pouring out large amounts of sweat and unable to concentrate urine). Examination of human fossils shows that we started eating aquatic animals, which have high concentrations of certain forms of fat. Rich supplies of aquatic foods, together with mutations in lipid metabolism enabled the brain to change.

The schizophrenia connection develops because, according to Horrobin, there is evidence – and he cites a considerable amount, although not enough to convince most experts – that the disease stems from changes in the biochemistry of the aforementioned fats in the brain. (Its expression, however, is linked with environment.) Additionally, the more saturated fat in the diet, the more severe the schizophrenia, which is why, although schizophrenia is suffered among every people in the world, it is worst in developed, industrialised societies. Throughout the book, Horrobin is careful to make clear that correlations between variables do not prove that one causes the other, but he marshals some impressive evidence, and cites instances of significant improvements in schizophrenia as a result of supplementing the diet with certain fats.

The next section of his argument Horrobin calls his ‘just so story’, his personal theory of evolution. He offers it up for consideration, not claiming to have conclusive evidence. But what an interesting idea it is. People with schizophrenia very commonly are themselves or have relatives who are highly creative or highly intellectual. There is also more psychopathy and violence in the families where schizophrenia is present. A classic symptom of schizophrenia is hearing voices. Horrobin puts all this together to suggest that, while we were living on the margins of rivers and eating our marine diet, the gene mutation which, in full blown form can lead to schizophrenia, took a positive form – creativity and development of intellect. The hearing of voices may have led to a belief in ‘someone out there’ and in turn led on to the development of
religious belief. As separate bands and cultures started to develop, so those with the relevant mutated genes might have been those who were ruthless enough to be leaders.

However, as humans settled and started to rear animals, our diet changed, and we no longer consumed high amounts of marine fats which, Horrobin hypothesises, had kept the abnormalities in brain fat metabolism relatively mild. Consequently, creativity flourished but so too did bizarre and sometimes violent behaviour. (People with schizophrenia are no more violent than the ‘normal’ population but those who are tend to be violent in headline-grabbing ways.)

It could be, he suggests, that the simultaneous presence of two, three or four genes will be found to be required for the florid symptoms of schizophrenia (and, through the Human Genome Project, we are likely to know within 20 years). Horrobin suggests that one will be found to be involved in dyslexia, another in manic depression, another in schizotypy and another in high intelligence, which are all commonly found in first and second degree relatives of people with schizophrenia. If three specific genes are needed for a full schizophrenic genome to occur, then well over half of the population is probably carrying one or two of them; if four are needed, then almost all of us may be carrying one, two or three of them.

This potted account does not do justice to Horrobin’s theory. He draws together a myriad of intriguing facts and makes his case modestly, carefully and cogently (if occasionally a little repetitively). If he is right, the exciting possibility is that treatment for schizophrenia can eventually be developed which is much more effective than drugs, and without their appalling side effects. But he and fellow researchers still have an uphill task against medical narrow mindedness, caused partially by the narrow ultra-specialisations of the
second half of the 20th century. “Only the open minded, who are willing to consider observations and explanations at many different levels are likely to make much impact on the problems that face us,” he concludes. And that, I would suggest, is the spirit also in which to approach his imaginative theory about our evolution.

This book review was originally published in Human Givens magazine Vol 8, no 2 Summer 2001. www.humangivens.com