The human body is an amazing structure. Unlike what some creationists claim, this structure was not created and put here on Earth in its present form by some divine force; rather, it was sculpted by evolutionary forces over billions of years. Over time, its various constituents have changed in form and function as a result of the workings of natural selection, in conjunction with mutations, genetic drift, and other factors responsible for causing evolutionary change.
Given that there has been ample time for natural selection to mold the genetic recipes that we humans carry with us, it may seem strange that our bodies aren’t better designed. In some ways, they seem almost perfect: Our hearts are constantly pumping out fresh, oxygenated blood to the various organs of our bodies; our muscles rapidly adapt following exposure to novel stimuli; and our digestive systems are highly proficient at turning many different types of foodstuffs into energy that our cells can use.
However, in others ways, our bodies seem flawed and damaged. Many of us have or will develop shortsightedness, heart disease, and acne vulgaris; our bones get fragile and weak when we get older; and over time, deleterious mutations develop inside our cells, something that can lead to cancer. Upon first inspection, it can seem like the human body was created by a negligent, sloppy, and unskilled designer.
Why is it that our bodies aren’t better designed? Why do so many of us get sick? Why aren’t we more robustly built?
In my recent article entitled The 6 Reasons Why Diseases Exist, I made the case that the answers to the questions can be found within the realm of evolutionary science. One of the main reasons our bodies aren’t unshakable and immune to disease is that the primary currency of evolution isn’t health, but reproductive success. Moreover, natural selection can’t do magic. It can’t go back and completely rebuild a structure from scratch; it has to work with what it’s got at hand.
Finally, natural selection is not as fast as Usain Bolt; it can’t keep pace with a rapidly changing environment. It takes time for adaptations to spread within a population, particularly if the environmental pressures are weak. If the speed of environmental change exceeds the speed at which natural selection operates, a conflict between the environment and the genetic make-up of the organisms that live in that environment may arise.
This leads us over to the main topic of today’s article…
The human body isn’t as flawed as it may seem
The human body isn’t as poorly “designed” as it may seem. It’s certainly true that it isn’t “perfect”; however, it’s not as flawed as it seems to be. As you undoubtedly know if you’re a regular reader of this blog, many of the health problems that affect the modern man don’t arise because of deleterious mutations or “design flaws”, but rather due to gene-environment incompatibilities.
Imagine that you had to uproot your whole existence, pack all your things, and move to a faraway place where you knew no one and the culture and language were very different from that of the place from which you came. It would probably take you quite some time to adjust to your new circumstances and find your place in the new and unfamiliar world. For some time, you would probably feel very confused and lost. It may even be that you would never fully get over what’s happened and get mentally comfortable with your new life.
This is not so different from how the human genome “feels” when it’s placed in a modern environment. From the perspective of the genes found inside our bodies, the manufactured milieu that we humans have created for ourselves is a foreign place that’s very different from the place in which they came into existence. The human genetic make-up expresses itself in strange and evolutionarily abnormal ways when it’s exposed to stimuli produced by highly processed foods, antibiotics, and many other things associated with our modern way of life.
This is true regardless of whether the genome in question is the one found inside you, your neighbor, or any other person here on Earth. Some people are more susceptible to the harmful effects of novel environmental agents than others; however, none of us are fully resistant to damage. We’re all inadequately adapted for the modern conditions of life. We all express a deleterious phenotype if we eat modern refined foods, don’t exercise, use strong pharmaceutical drugs, and/or expose ourselves to a lot of technology and artificial light at night.
The list of diseases and health problems that are wholly, largely, or partly caused by gene-environment conflicts is staggering. It contains myopia, acne vulgaris, colon cancer, diabetes, lower crossed syndrome, obesity, malocclusion, and many other health disorders (1, 2, 3, 4, 5). Moreover, it has poor general health written with big letters on the top. This entry is there to make it clear that evolutionary mismatches don’t just produce diseases per se, they can also create malaise. Very few, if any, contemporary humans are truly healthy. Some people have never been diagnosed with a disease; however, that doesn’t necessarily mean that their bodies are working at a peak level.
Here’s what Harvard Professor Daniel Lieberman had to say about the prevalence of mismatch diseases in the excellent book The Story of the Human Body: Evolution, Health, and Disease:
I don’t think it is possible to overemphasize just how important mismatch diseases are. You are most likely going to die from a mismatch disease. You are most likely to suffer from disabilities caused by mismatch diseases. Mismatch diseases contribute to the bulk of health-care spending throughout the world. (2)
Mismatch resolution explained
Simply stated, mismatch resolution involves resolving mismatches that exist between genes and environment. It’s not a generic approach to healing that involves following a strict set of rules; rather, it’s a general set of principles that one can use to understand, prevent, and treat disease. Diet and lifestyle interventions obviously play an important role in the context of mismatch resolution; however, other things, such as medical treatments aimed at manipulating the human microbiota, are also a valuable part of the toolkit of evolutionarily oriented physicians.
The goal of mismatch resolution is not to turn the clock back and bring the human species back into the wild. Rather, the goal is to remedy some of the damage that we’ve caused via our reckless and irresponsible behaviors in the context of niche construction, and harmonize the inharmonious relationship between the human genome and the modern environment by adjusting our modern lifestyle in such a way that It agrees better with the genetic legacy that has been passed down to us from our ancestors.
In the infographic below, which I recently created, I’ve illustrated what happens when the human genome is exposed to a modern environment and why mismatch resolution is such an important part of Darwinian medicine.
Where are we heading?
The idea that a major reason why so many contemporary humans are in poor health is that our genes aren’t compatible with our milieu is an essential part of the foundational structure upon which the field of Darwinian medicine is built. It’s far from the only premise that’s important in the context of evolutionary health promotion; however, it does hold a unique place within the world of (r)evolutionary medicine.
Sadly, this powerful concept has not yet made its way into institutions that educate nutritionists, doctors, and other health professionals. Most health practitioners didn’t learn anything about evolutionary mismatches, hunter-gatherers, organic fitness, or other ancestral health-related things in school. I believe this represents a major flaw of our educational system.
A health professional who’s knowledgeable about the evolutionary mismatch concept operates at a very different level than those who are in the dark about this concept. When compared to the latter, the former has a much easier time finding his way in the jungle that is modern medicine, seeing as he’s accompanied by an evolutionary guide that points him in the right direction.
If evolutionary theories, ancestral health concepts, and ethnographic research pertaining to the health of hunter-gatherers and traditional people were to be incorporated into medical training and health care, our medical system as a whole would be elevated to a new level. Not every disease and health problem can effectively be addressed via mismatch resolution; however, there is no doubt in my mind that many can.
Perhaps needless to say, not every patient is interested in changing the way he lives his life in such a way that his genome comes into better alignment with his milieu. Many just want a quick fix; a drug that can help ease their pain. With that said, I think this group of patients is in a minority. Particularly people who are very sick are typically highly motivated to put in the effort that is required of them to get better.
In the future, I hope mismatch resolution, which includes microbiome restoration, becomes a prioritized part of health care. I don’t know if it will, but if it is, I think it could dramatically change the way medicine is practiced. Not only will we become better at preventing and treating human diseases, but we will also get better at preventing and treating diseases that affect pets and other animals, seeing as the evolutionary rules that apply to us also apply to them. At some point, mismatch resolution will have to become a part of health care, or else, we won’t be able to restore the health of our species, nor the health of the animals we’ve domesticated.
We can’t expect natural selection to eliminate our problems, seeing as most of the diseases of civilization have little impact impact on reproductive success in the context of the modern, built environment. Furthermore, we can’t expect to be able to develop technology that allows us to edit our genomes in such a way that we become resistant to all disease, seeing as most diseases arise as a result of complex genome-environment interactions, not as a result of one or a couple of deleterious genes.
Picture source: EvolutionMedicine.com