If you suffer from allergies you know how pollen, dust, or the wrong ingredient in food can ruin a day (just be thankful you’re not allergic to meat). Those with severe allergies have to be on high alert when trying new foods or going to a house where a cat lives. The suffering can reach philosophical levels at times; making one wonder, ‘Why me? Why today? Why peanuts?’
Geneticists and historians have been hard at work on the ‘why?’ questions surrounding allergies. While their findings may not give you any relief from those itchy eyes, the information may distract you for a few minutes while the Benadryl takes effect.
One Nasty Bug
The real culprit behind allergic reactions is an overreaction of our immune systems. The immune system generally works to keep foreign substances (including invading bacteria and
viruses) out of our bodies. But when the immune system kicks into overdrive, allergic symptoms like itchy rashes, swelling, red eyes, runny noses, and shortness of breath appear as side effects.
After centuries of studying allergies, researchers have isolated the IgE antibody as a major player. Antibodies work to recognize foreign bodies and alert white blood cells to fight them. IgE is an especially tenacious antibody, and tends to keep white blood cells in the ‘alert’ state longer than most antibodies do. Scientists speculate that an especially tough disease hit our ancestors millions of years ago and the humans that developed IgE antibodies were the ones who could survive. This protein remains as remnant evidence of our natural history, playing out an ancient battle every time pollen season comes around.
Agricultural Revolution & Animal Domestication
Around 10,000 years ago, the human lifestyle changed in a big way. With the development of agriculture, humans started on a path that would lead to large civilizations and leaps in technology. Humans started planting grains and other crops to feed themselves and domesticated cats and cows (dogs had been domesticated 20,000 years prior). Grains were an easy, plentiful source of calories for people, but the new diets did not agree with everyone.
Aretaeus, a 2nd Century resident of the Fertile Crescent, gave the first account of what is now known as celiac disease, an allergic reaction to a protein in wheat that affects around 1% of the global population. Symptoms include digestive problems, pain, anemia, fatigue, and developmental issues in children.
Early ranchers and nomads domesticated cows around the same time agriculture was invented, and started drinking cow’s milk not long after. All mammals drink milk as infants, but most lose the enzyme responsible for breaking down lactose sugar as they age. Human populations that were herding cows developed a lactose tolerance, while those that didn’t engage in herding remained lactose intolerant. Today, European populations and their descendants have lactose intolerance rates as low as 5%, while some Asian and African populations are 90% intolerant.
The Industrial Revolution & City Living
The Industrial Revolution signaled another huge shift in human history. Machines were invented that could work for humans. Huge factories replaced hand tools and small manufacturing operations. The move to cities began in earnest while the frequency and flavor of allergies changed along with our lifestyles. No longer were we working outside in the dirt and pollen alongside animals, instead we worked inside, in cleaner and cleaner environments.
Dr. Erika Von Mutius, a health researcher in the 90’s, was working on a hypothesis: children who grow up in less hygienic conditions have more allergies when they grow up. It made sense to her; dirtier conditions might lead to poorer health and more allergies. She compared allergy and asthma rates from the relatively poor East Germany to those in the more affluent, clean, and healthy West Germany. Her hypothesis was wrong. The East German children had fewer allergies.
Another study in Germany found that the children of farmers had no instances of hay fever in the year prior to the study, while 20% of children with no contact to farms had it.
As we have learned since these studies, whether or not a person gets a particular allergy generally depends on their early childhood. If a baby is born into a home with a cat, it is unlikely that they will grow up with an allergy to cats. If a baby is around ragweed pollen as it fills the air (one ragweed plant can release 8 billion pollen grains in 5 minutes, so the air really is filled), that ragweed pollen likely won’t have as big an effect on their immune system later in life.
Living in cities also introduced people to some brand new allergens. Rats, cockroaches, and dust mites all inhabit crowded cities in huge numbers. Their waste products are major causes of allergies and asthma, whether you grow up around them or not.
As the understanding of allergies and asthma grows, diagnoses also become more prevalent, but over diagnosis has also been shown in recent years. While shifts in where we live, diet, and behavior change the face of human allergies, awareness and treatment options for them have never been better. Education about allergies makes schools, homes, and foods safer for those children affected by them, while doctors and scientists work to deliver a long-term solutions in the near future.