What is Evolutionary Medicine?

What is Evolutionary Medicine?
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Charles Darwin’s theory of evolution would suggest that our vulnerability to certain diseases is an evolutionary trait that has been selected for down the generations. After all, these are traits which have survived for thousands of years. But this seems highly illogical – surely it would be counter-productive for traits which make us vulnerable to lethal illnesses to survive in a population.

Evolutionary medicine is a relatively new branch of medical science which seeks to understand why humans remain vulnerable to disease. How have we been able to evolve complex structures such as eyes and brains, but unable to evolve to the point where we are no longer vulnerable to diseases such as cancer?

In some cases, genes which cause disease are the result of mistakes which somehow produce a beneficial effect.

One example of this is the sickle cell gene. Mutations in the sickle cell gene cause a serious type of anemia. People with one copy of the mutated gene are carriers of the disease, while people with two mutated copies develop the disease. This harmful mutation carries a benefit, however, in that people with one copy of the mutated gene are resistant to malaria.

There are several other evolutionary explanations which may account for the existence of these types of vulnerabilities.

Random events – some design flaws may simply be the result of chance mutations that were not initially harmful, and which therefore were not selected against.

Sometimes, problems arise simply because our bodies weren’t designed – they evolved over millions of years, and when it comes to evolution there are no do-overs. It would, for example, be more advantageous if our respiratory and digestive systems didn’t share an airway – but it’s too late to go back and change that now.

Competition between living organisms is also a factor. Natural selection has affected every living thing on the planet – including human pathogens, which generally benefit from causing disease. (Natural selection has also provided us with defense mechanisms such as pain, fever, and inflammation.)

Of course, there are simply mutations which were once neither harmful nor beneficial – with natural selection neither selecting for nor against them. In the modern society, these may now cause disease due to changes in diet and other lifestyle factors which negatively interact with certain genetic variants.

A related factor is simply that the human body as it is now may not have had time to adapt to a modern environment. This theory is the basis behind the Paleolithic diet, which emulates the Stone Age hunter-gatherer diet, excluding grains, dairy products, and legumes, as well as salt and refined sugar.