Does Survival of the Fittest Really Apply to People with Migraine?
Now here is a question that I have asked myself a few times throughout the years. While under the spell of a migraine, I really don’t see a whole lot of advantage in suffering from this debilitating pain. Nevertheless, it is obvious that genetics play a role in migraines and therefore subject to evolutionary natural selection and survival of the fittest.1 I have recently come across a research paper that discusses some of these advantages and would like to share them with you, fellow migraineurs : ).
Natural selection and survival of the fittest 101
At one point or another, we have all heard of Charles Darwin (an apparent migraineur himself), the scientist who coined the term “natural selection” back in the 1850s. Natural selection is the process by which traits that provide creatures with the most “fitness” for the environment are passed down to future generations. Organisms possessing traits that give them an advantage or disadvantage to adapt in their environment will, in consequence, have different reproductive and survival rates. Even a trait that offers only a minor advantage will, over millions of years of evolution, be strongly selected for; this is in contrast to traits which reduce reproductive fitness, even marginally, which are eventually eliminated.
Hard to believe that debilitating pain such as that experienced by migraineurs would give us an advantage in the greater scheme of evolution – or even put us in the “mood”. As the author explains in his research paper, there are numerous advantages associated with having some people within the general population exhibiting traits that don’t fit the “norm”.
So what is the evolutionary advantage of migraine?
A new branch of medical science known as ‘Darwinian medicine’ led by Randolph Nesse and George Williams attempts to examine the possible adaptive value of genetic vulnerability to diseases. They have put forward five explanations for what appears as deleterious diseases and vulnerabilities being favored by the forces of natural selection. “First, some discomforting conditions, such as pain, fever, cough, vomiting and anxiety, are actually neither diseases nor design defects but rather are evolved defenses. Second, conflicts with other organisms—Escherichia coli or crocodiles, for instance—are a fact of life. Third, some circumstances, such as the ready availability of dietary fats, are so recent that natural selection has not yet had a chance to deal with them. Fourth, the body may fall victim to trade-offs between a trait’s benefits and its costs; a textbook example is the sickle cell gene, which also protects against malaria. Finally, the process of natural selection is constrained in ways that leave us with suboptimal design features, as in the case of the mammalian eye.”2
Similarly, one could adopt the Darwinian medicine principles to postulate possible evolutionary explanations for migraine as suggested by Loder:1
Migraine as a defense mechanism
- Early detection and avoidance of predators
- Detection and avoidance of toxins in the diet (some of us do experience some form of food intolerance)
- Aversion to a novel, possibly dangerous situations
- Avoidance of hunger, lack of sleep
- Protection against cerebral vasoconstrictive emergencies that threaten brain survival. Migraineurs tend to experience dilation of large cranial arteries which may provide an edge
- Potential protection against tumour growth (reduced prevalence of malignant neoplasm)
Migraine as a result of conflicts with other organisms
- Enhanced response to central nervous system infection where increased vasodilation in the migraineur helps bring extra blood flow and immune cells to the brain to fight pathogens
- Non-specific result of central nervous system infection relates to the possibility that at least some forms of migraine might be related to infection in other parts of the body and can serve as a warning call to pay attention
Migraine as a result of novel environmental factors
- The inability of the central nervous system to deal with environmental challenges such as getting migraines if it is too hot or too cold or too damp which may have promoted for people to migrate and spread their genes
Migraine as a compromise between genetic harms and benefits
- Multiple benefits of an overstimulated central nervous system in some outweigh the hurdles of dealing with severe headaches where one genetic trait gives you an advantage in surviving over another
Headache as a design constraint
- Imperfect interconnections between older and more recently evolved brain structures could play a role in generating or failing to suppress an acute attack of migraine
It’s fair to say that despite the evolutionary advantages of migraine and its persistence over millions of years, the battle against coping with the illness is not an easy task. By virtue of natural selection, several minor variations in the genes that affect our central nervous system have settled on traits which promote easy activation of the trigeminovascular system (neurons in the trigeminal nerve that innervate cerebral blood vessels).
Loder admits that some of the hypotheses examined in his paper may seem “fanciful or far-fetched” but it does offer us migraineurs a way to think about migraines where several of the clinical manifestations of this condition might then be recognized as adaptive, despite the immense pain that we experience.
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