Happy cave families: Evolution designed mankind to eat game and nuts and berries
Is the cold cure at odds with man's origins?
To treat illnesses such as winter colds and flu, should we forgo antibiotics and other modern cure-alls? Science Editor Roger Highfield asks whether the lifestyle of our hunter-gatherer ancestors offers lessons for today.
AS WARNINGS of a flu epidemic make headlines, advertisements for remedies flood the media, promising to cut the misery of winter coughs and sneezes. But do we take these treatments at our peril?
Modern medicine blindly treats the symptoms but stifles efforts to combat disease, according to advocates of an ambitious new movement which is using 19th-century wisdom to undermine conventional medical ideas.
Its underlying message sounds reasonable enough: human beings and their illnesses are the fruits of an evolutionary history stretching back millions of years. Yet such a perspective could profoundly alter the way we live.
Today's treatments largely ignore the implications of Charles Darwin's revolutionary work on evolution. So say Drs George Williams, a biologist from the State University of New York, and Randolph Nesse, a psychiatrist at the University of Michigan.
"Advances in medicine would be even more rapid if medical professionals were as attuned to Darwin as they have been to Pasteur," they say in their book Evolution and Healing (published by Weidenfeld & Nicolson), which propounds "Darwinian medicine".
This month, Williams chaired one of the prestigious Darwin Seminars at the London School of Economics, flew to Switzerland to organise a major meeting, then flew back to attend the Telegraph's science and media party. Firing his missionary zeal is the potent light that Darwinian medicine casts on everyday misery.
Sneezing, coughing and vomiting, for instance, have evolved as defences against disease organisms. During the course of evolution, fever may have become a way to make the body too hot for the invading microbes to thrive; morning sickness may prevent women from eating toxic foods that harm the unborn child; menstruation may help to flush the uterus free of harmful microbes delivered by incoming sperm.
Reduce fever with an aspirin and you may prolong infection by a virus. "Drugs that claim to control fever or coughing are frequently not doing what they are supposed to - and even when they do, it may be counterproductive," said Dr Williams, arguing that much more must be done to understand our symptoms before doctors disable what could be a crucial disease-fighting mechanism.
In medicine as in biology, a Darwinian approach explains a multitude of facts with a few assumptions. From an evolutionary view, we are a muddle of design compromises: the price of standing on two feet are back pains; the price of cell division that makes tissue repair so effective is cancer; the price of a powerful immune system is arthritis, when that system runs amok; the price of anxiety, an adaptive response to danger, is panic disorder.
Our bodies are a direct result of survival of the fittest, an endless arms race between our ancestors over millions of years as they fought off parasites, predators and disease. It takes some hubris to write off the threat posed by bacteria, organisms that have thrived on Earth for 3.5 billion years. Yet in 1967 William Stewart, the US Surgeon General, told a White House meeting that "the time has come to close the book on infectious diseases."
Now, however, bacteria are fighting back: survival of the fittest means that any microbes that withstand treatment with an antibiotic can evolve further to become resistant strains. In May next year the issue will come to a head when the World Health Organisation publishes its World Health Report.
Who regards bacterial resistance as one of the most important health problems of this decade, according to a spokesman for the report. Infections such as tuberculosis and gonorrhoea have already become resistant to first and second-line drugs, and development of new antibiotics to replace them lags far behind.
Failure to appreciate how the inappropriate use of antibiotics aided the evolution of resistance has contributed to the problem, Williams said. Bacteria can rapidly mutate to fill a niche, no matter how inhospitable. They can thrive even in boiling water.
Resistance to drugs is stimulated when doctors inappropriately prescribe antibiotics, notably to treat a sore throat caused by a virus. Irregular use of the drugs, or failure to take a full course, encourages partially resistant strains to survive. Scientists also suspect that the widespread practice of feeding antibiotics to farm animals - to boost health of the livestock and extend shelf life of the product - encourages resistance. The Darwinian outlook not only makes resistant infections a predictable phenomenon but also changes the way we view hereditary disease and what we mean by bad genes.
The most common gene defects turn out to have benefits: sickle-cell anaemia, where a single copy of the defective gene confers immunity to malaria without causing anaemia; those predisposed to non-insulin-dependent diabetes have lower energy requirements, so they risk starvation less, according to work at Imperial College, London.
And white people who are carriers of cystic fibrosis may have enhanced resistance to cholera, according to a University of North Carolina team. Other likely candidates are diseases of old age: genes that cause diseases such as Alzheimer's and osteoarthritis, for example, may confer beneficial effects early in life.
Nesse and Williams caution: "If we naively assume that ridding the population of the genetic capability for Alzheimer's disease is an unconditionally desirable goal, we might incidentally eliminate unsuspected benefits."
For areas of medicine such as infection and genetic diseases, the message of the Darwinian approach is that by asking questions about evolved function, doctors will be better placed to design treatments. For the diseases of civilisation, the approach highlights the mismatch between the evolutionary and modern context of Homo sapiens.
Physiologically, human beings still belong in the Stone Age when diets were very different from today's, says Boyd Eaton, an anthropologist at Emory University in Atlanta. He argues that people should turn the clock back 15,000 years and eat like cavemen if they really want to stay healthy.
"Our ancestral diet is that for which our genetically determined metabolism was originally designed," he told a recent meeting. "The deviations from it which characterise nutritional patterns common in affluent nations foster degenerative disorders."
We should be eating the food we are genetically designed for - the same consumed by our hunter-gatherer ancestors. That means a diet of wild game, uncultivated fruit and vegetables like nuts, berries and tubers, little or no cereal and no dairy foods. In a similar way, our appetites and cravings are customised for an environment that was poor in salt and fat. Today, we live long enough for the high levels found in urban diets to wreak havoc on our bodies.
Cancer and heart disease are not only the product of metabolism gone to pot, but of living in conditions different from those for which our bodies evolved.
