Evolutionary Medicine
How Evolutionary Theory is Helping the Field of Medicine
Homo sapiens, as with all life on Earth, has been fashioned by the process of evolution. Once regarded as a perfect 'design', modern science has revealed the numerous flaws and problems inherent in the human body. These range from the physical to the mental, in both the old and the young. Today, pioneers such as Randolph Nesse are developing a new branch of medicine using evolutionary facts.
Historical Accidents in Evolution
An engineer, when faced with a modern engineering challenge, can start from scratch. Submarines were not adapted from boats, they were purposefully designed for a specific environment and role. Evolution has no such flexibility, it must make do with the current state of a species.
The result is a planet teeming with organisms, all of which are riddled with biological 'quick-fixes', rather than long-term and perfect strategies for survival. Take, for example, the human eye. Often used by creationists as an example of perfection in nature, it is instead a flawed structure, and one which any camera engineer could improve with ease. The main problem lies with the blind-spot, an area on the retina where the optic nerve connects to the brain.
Like with any flawed structure, things go wrong. As Randolph Nesse, a leader in Evolutionary Medicine comments "No sensible person would have ever left the body the way it is".
Trade-offs in Evolution
A trade-off in evolution is where nature 'allows' something that is beneficial to a young organism, but detrimental to an old one. Or, where nature permits one advantageous aspect, despite causing disadvantages elsewhere.
An example would be a heightened sense of anxiety. For human ancestors, fleeing a potentially dangerous watering hole may result in a reduced in-take of water, but not fleeing when a threat is perceived could result in death. Even if 99 times out of 100, the threat was a false alarm, the trade-off may be worth-while.
Evolutionary medicine would then interpret a patient suffering from anxiety attacks in such a context. Rather than a problem, anxiety is seen as a perfectly natural response to the world, a response fashioned by evolution.
Humans and Modern Life
One large area of evolutionary medicine is in understanding the effects of modern life on human beings. It is known that excessive amounts of fatty food and a lack of exercise are extremely detrimental to health. But why? Evolution has a clear answer. The human body has been fashioned, over millions of years, for a specific type of environment and life-style. Food and water were in limited supply, the food available tended to be much lower in sugar, salt and fat than some modern food, and large amounts of exercise was vital for survival.
Evolution takes large amounts of time and large numbers of generations to work (at least in organisms like humans). In the evolutionary blink of an eye, people today are permitted to eat vast quantities of fat, sugar and salt, and get little or no vigorous exercise. The result of this mismatch between evolutionary design and modern living results in massive epidemics of illness and disease, including heart-disease, obesity, diabetes, and depression.
Further Reading
- Nesse, Randolph M. & Williams, George C. Why We Get Sick: the New Science of Darwinian Medicine. Times Books (1 Oct 1995).
- Interview with Randolph Nesse on Evolutionary Medicine, presented by Richard Dawkins.
Modern Medicine is Learning From Evolution
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