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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 chizophrenia. 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
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