Many of us have experienced the misfortune of suffering an allergic reaction. These types of reactions are showing a continuous increase in their prevalence, as it is estimated that between 30 and 40% of the world’s population has suffered from them at some point. However, how does the allergy develop?
As bothersome as it is, allergy can hide an essential evolutionary significance for humans. It is an immune reaction of the body against a substance that is generally harmless to the host, which manifests itself through characteristic signs and symptoms when the host is exposed to it.
Antibodies in the immune system of the person suffering from this condition recognize the harmless agents in the environment as potential dangers and act accordingly to expel them. This generates inflammation of different degrees in the paranasal sinuses, skin, digestive system, among others.
This is how the existence of allergies makes us think: why does our own defense system boycott us in harmless situations? So that we can better understand, we detail the role of allergies in human evolution and development below.
How does allergy develop?
The real purpose of allergic reactions remains a topic of debate and research today. The hygiene hypothesis proposes that allergies spread globally due to lack of exposure to real pathogens.
A study published in Plos Computational Biology argues that the proteins found in elements of daily contact with humans are similar to those in bodily parasites.
The lack of activity of our immune system in contact with these types of harmful living beings could cause it to detect any other similar signal as a potential danger, causing the reaction in question.
The previously mentioned study provides evidence to support this hypothesis:
- The research team monitored the laboratory reaction of antibodies to a protein from a species of parasite, Schistosoma mansoni. The protein in question was very similar to the one present in birch pollen.
- The same antibodies responsible for removing the parasite’s protein were the ones that reacted to the birch pollen.
These results, while simple, provide a great deal of information. It’s possible that the lack of real alarms causes our immune system to manufacture its own.
A not so accidental answer
We could stick to this possible explanation, as it seems convincing and seems scientifically proven. Still, there are other currents that defend different ideas.
Some studies in this Scientific American article suggest that these types of reactions are not accidental. They propose that allergy can protect us from toxins in the environment:
- In one study, rats were exposed to small doses of poison and, after several weeks, to more concentrated doses of poison. Some rats were inoculated only with the concentrated dose.
- Rats that were exposed to small doses had a much greater immune response to the concentrated dose than those that did not receive the initial inoculation.
- Exposure to an initial dose made those previously inoculated to develop specific antibodies to allergens, preparing them for more serious future scenarios.
What could this mean?
Interpreting the results, it is not unreasonable to think that, with vomiting, shortness of breath and other symptoms, our bodies are preparing us for situations of real danger.
Our immune systems may be preparing for other, more serious future reactions, while communicating that we should try to avoid these allergic substances.
Furthermore, this theory suggests that an allergy develops as an evolutionary mechanism in humans. Based on experience with harmless agents, we could have learned to avoid higher risk situations as a species. Furthermore, our immune system would train its action against serious dangers with these minor allergic episodes.
Why does allergy develop? an unanswered question
As we have seen, there are several theories about the emergence of allergies. So far, there are no certainties or misconceptions, but different ways to approach a global pathology. Still, the real reason behind the development of allergies remains unknown.