Table of Contents
The Story of Germs
Most people think germs are invisible pests that cause disease. The less of them, the better. We disinfect our homes, food, and bodies with a collection of germ-killing weapons, including soap, bleach, and antibiotics. No one questions the assumption that cleaner is healthier. And for good reason. Sanitation and antibiotics has saved more lives than any advancement in medicine.
But from an evolutionary perspective, our sterilizing behavior is abnormal and potentially harmful. One reason is that your body is host to a microbiome: trillions of other organisms that live in your gut, skin, and respiratory tract. Some estimates say that there are ten times as many foreign microbes in your body than your own cells.
We co-evolved with these microbes which is why most of your microbiome is harmless or helps with important functions like cleaning your skin and helping with digestion. You depend on them as much as they depend on you.
If you get rid of them, you will suffer. Antibiotics and antiparasitic drugs don’t eliminate your entire microbiome, but too much of these strong medications can kill a lot of good microbes and worms, whose absence will lead to diseases.
Another reason you shouldn’t sterilize everything or use antibiotics too much is that some microbes seem to play an important role in helping to stress the immune system properly. Just as how your bones need stress to grow, your immune system needs germs to mature properly. To match capacity with demand, your immune system needs practice. A low immune response to a pathogen can cause death, but too much of a response is also dangerous, in the form of an allergic reaction or autoimmune disease (when the immune system attacks its own body cells by mistake).
As with other systems, the first years of life are instrumental in training your immune system. When you leave your mother’s womb, you are attacked by pathogens and viruses. Breast feeding provides an immunological umbrella – antibodies to help fight off infections. Hunter-gatherer children usually nurse for around three years, giving their undeveloped immune system plenty of help as they grow in a world full of germs and worms.
The idea that some filth is normal and necessary for the development of a strong immune system is known as the hygiene hypothesis. This has changed the way we think about many diseases, from inflammatory bowel disease and autoimmune disorders to cancers and even autism.
Allergies are an over-response of your immune system; they can be mild or severe. These responses include swelling of airways, skin rashes, itchy eyes, runny noses, vomiting, and more. A bad trend, that shows environmental mismatch, is the rise of asthma and allergies in developed countries.
The incidence of these disorders has more than tripled since the 1960’s in high-income nations. Could lack of exposure explain this?
Looks like it. To explore why too much hygiene could cause innocuous substances like milk or pollen to trigger severe and potentially deadly overreactions, we should understand how the immune system protects us. When a foreign substance enters the body, special cells digest the trespassers and display the fragments (antigens) on their surfaces like Christmas tree ornaments. Immune cells known as T-helper cells are attracted, and make contact with the antigens. When the T-helper cells are tolerant of the antigens, they don’t do anything. ut sometimes, a T-helper cell decides that an antigen is threatening. In this case, the T-helper cell either recruits giant blood cells, which digest anything with this antigen (appropriate for viruses), or activate cells which produce antibodies specific to that foreign antigen.
There are many kinds of antibodies but allergic reactions always involve IgE antibodies. When these antibodies bind to an antigen, they attract other immune cells, which launch all-out war on anything that has the antigen. Histamines are one of those weapons, and they cause inflammation (rashes, runny noses, clogged airways). They also trigger muscle spasms, contributing to asthma, diarrhea, coughing, and vomiting – methods to expel the invaders.
Antibodies protect your from bad pathogens, but they cause allergies which target harmless substances. The first time this happens, the response is mild, but your immune system has a memory, so when you encounter the same antigen, there are antibody producing cells specific to that pathogen ready to pounce.
When they do pounce, your attack cells act like a swarm of killer bees, creating a massive inflammatory response that can kill you. In this way, allergic reactions are like inappropriate immune responses caused by misguided T-helper cells.
The reason why this is relevant is that sterile environments lead to unemployed T-helper 2 cells swimming around, increasing the chances that one of them will make a big mistake and target a harmless substance as an enemy When this happens, an allergy develops.
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The original hygiene hypothesis has received plenty of attention but does not explain why many allergies are becoming so common. One theory – “the old friends” hypothesis – states that many allergies and inappropriate immune responses happen frequently because we have abnormal microbiomes. For millions of years we have lived with many microbes, worms, and tiny critters. These microorganisms were not totally harmless, but it was adaptive to tolerate them by keeping them in check rather than launching all-out war against them.
Life would be short and miserable if you were always sick, fighting a large battle against every bug in your microbiome. Many inappropriate immune responses like allergies become more common in developed nations because we have disrupted the old equilibrium that our immune systems co-evolved with “old friends.”
Because of antibiotics, bleach, mouthwash, water treatment plants, we don’t encounter many types of bacteria and worms. This freedom has a price – an overactive immune system. The “old friends” hypothesis explains why exposure to germs from animals, water, and dirt is linked with lower rates of allergies.
This helps explain accumulating evidence that exposure to some parasites helps treat autoimmune diseases like inflammatory bowel disease, and multiple sclerosis. Soon, doctors may prescribe you worms or feces.
No Pain, No Gain
We live in comfort and cleanliness that no caveman could ever imagine. But just because we can live very clean and comfortable lives does not mean cleanliness and comfort are good for us, especially children. To grow properly, every part of the body should be stressed appropriately. Like how not requiring a child to reason critically will stunt their intellect, not stressing their bones, muscles, and immune systems will fail to match the capacities of these organs to their demands.
The solution is not to go back to the Stone Age. Many people today would be dead without modern sanitation and antibiotics. But we should think about how much cleanliness is too much. Like exercise, too much dirt is bad, and too little is bad.
Humans are born with millions of sweat glands, but the percentage of glands that secrete sweat when you get hot is determined by how much heat stress you experienced as a child.
The environment influences your body dynamically, even in adults. Weight-lifting will make your muscles tired, but then bigger and stronger. If you were confined to a bed for months, your muscles and bones would atrophy.
Muscle is an expensive tissue to maintain, consuming around 40 percent of your body’s resting metabolism. We evolved to “use it or lose it.” Bodies are not engineered; they grow and evolve.
Children who played tennis have bones in their racket-swinging arm that are up to 40 percent thicker and stronger than in their other arm. Children who run and walk more develop thicker leg bones. Children who chew harder tougher foods develop thicker jaw bones (while tooth position is shapes by genes, proper tooth position in the jaw is highly influenced by chewing forces). No strain, no gain.
Comfort
Shoes protect the soles of your feet. Calluses are made of keratin, a flexible hair-like protein that your skin generates when you spend more time barefoot.
Not wearing shoes creates a circle of dependency, it hurts to go barefoot without calluses, which leads you to wear shoes. A shoe’s soles are more protective than calluses, but the soles limit sensory perception.
The rich, extensive network of nerves on the bottom of your feet provides important information to the brain about the ground beneath you, and activates key reflexes that help you avoid injury, when you sense something sharp, uneven, or hot. Shoes interfere with this feedback. The thicker the sole, the less information you get. Even socks lessen stability, which is why martial artists and yoga practitioners prefer to go barefoot to enhance sensory awareness.
Sitting in a comfy chair is pleasant, but from an evolutionary perspective, this kind of sitting is unusual. Are chairs unhealthy? Maybe, but this does not mean we should eliminate chairs. Although, here are some concerns. One relates to energy balance. Sitting expends less calories than standing – you are not tensing leg, back, and shoulder muscles as you support your weight. Over time, the energetic difference is very large.
Another problem is that many hours of sitting comfortably results in muscle atrophy, especially in core muscles of abdomen and back. La-Z Boy chairs are so comfortable because they reduce the use of all your muscles, but there is a price to pay for this comfort.
Muscle deteriorates by losing muscle fibers, especially slow-twitch fibers that provide endurance. Months and years of sitting in poor posture in comfortable chairs and other sedentary habits cause muscles to quickly fatigue. In contrast, sitting or squatting on the ground or on a stool requires more postural control from many muscles in the back and abdomen, helping to maintain their strength.