The Disruption of Our Biological Equilibrium - Evolutionary Mismatch Theory (by Danielle Steinbach)

By Danielle Steinbach

Whenever you ask someone why humans survived as a species, the answer is generally the same: “Our intelligence”. Yes, the thing that carried us through near-extinctions and famines and droughts was always our ability to think our way around it and innovate. 

In the world of biological anthropology, however, some have begun considering the possibility that our tendency to innovate could in fact contribute to our downfall as a species. 

That brings us to the idea of evolutionary mismatch theory. This theory suggests that we, as a species, may be too smart for our own good. While we may believe ourselves to be the  one-in-a-trillion species capable of outsmarting our environment and any conditions Mother Nature throws at us, recent health phenomena in the past few decades would indicate otherwise. 

Although the human population has expanded remarkably, a growing pile of statistics reveals that we are in some ways growing sicker and sicker as a species. In the space of about one decade, the occurrence rate of strokes rose by 7.8%. From the 1960’s, the prevalence of obesity in America has multiplied by more than an order of magnitude, and diabetes cases have skyrocketed. Psychiatric conditions like depression and anxiety have come to plague more people than ever, particularly targeting adolescents. More than one-fourth of Americans suffer with more than one chronic health condition. 

This would seem puzzling – as we proceed further into the twenty-first century and our medical resources become more advanced with technologies emerging to make our lives more convenient, we keep on declining in health. 

While you might think chronic illnesses are spiking in spite of modern innovations, evolutionary mismatch theory points to the possibility that these illnesses are spiking because of modern innovations. This theory posits that, while we keep industrializing and shaping our surroundings to be a specific way, our bodies became adapted long ago to the ancient lifestyle of early humans, based on foraging and hunting for sustenance, subject to a varying environment. Essentially, the gap between our modern environments and what are bodies are evolutionarily acclimated to is widening. We are designed to be constantly moving, interacting with family and friends in person, operating in communities, and using night-day cycles to dictate our schedules – this was what characterized the life of early humans. Now look at what our lives have morphed into in a relatively short period of time from an evolutionary perspective. Many of us walk less than 4,000 steps per day with office jobs that require sitting. We isolate ourselves from the world and rely on screens as a proxy for true communication. As for following our natural circadian rhythms, if you ask a high school or college student whether or not they follow a regular sleep schedule and wake up naturally with the sun, you’ll likely find yourself getting laughed at. So what are the consequences of all these changes? Our bodies are over-strained and revolting against us – with hypertension, high cholesterol, cognitive decline, inflammation, and other symptoms culminating in the wave of chronic illness we see today. 

Essentially, we are in a battle between our psychology and our physiology. Our brains respond to modern luxuries and comforts with glee, but our bodies bear the brunt of the consequences of our modern lifestyles. 

One of the biggest problems arose with the development of modern eating patterns and easily accessible fast foods. These foods have been engineered to be delicious, to stimulate our dopaminergic signaling until we enter into a destructive spiral of unhealthy eating. The more we eat these highly processed foods, the more our tolerance for its addictive compounds increases, the more difficult it is for dopamine to bind to the neurons in our reward pathways, the less dopamine the ventral tegmental area releases in response to the same amount of junk food, and the more of the fast food we crave. These foods are modern comforts, quick options to satiate us and stimulate the nucleus accumbens immediately – they satiate us, but they don’t sustain us. The human body evolved to operate on the foods we hunted and foraged directly from the Earth. We can see the many ways in which these modern engineered foods are destabilizing our bodies’ careful equilibriums. As sugar enters into our systems, our bodies release more insulin to induce cellular absorption of the circulating blood sugars. 

And more insulin. 

And more insulin. 

Then, as our bodies become gradually more resistant to insulin, we perceive a greater need for energy as our cells struggle to utilize the sugars in the blood. And so the eating continues, getting progressively worse. A year passes, then two, then five, then ten, and many of us find ourselves getting notified by our physicians that our lab work shows concerning signs of pre-diabetes, high cholesterol, and hypertension. 

For many people, though, these problems with food only make up the tip of a great iceberg. With the advent of social media and online websites, people are drawn more towards their screens than they are to sleep. 

Roughly thirty percent of people surveyed by a group at the University of Pittsburgh School of Medicine admitted to regularly using social media at least a half hour before sleeping. Meanwhile, multiple reviews have correlated screen use right before sleeping with circadian rhythm dysregulation. For hundreds of thousands of years, our species has dictated daily routine through environmental light patterns. Our brains have not had time to fully distinguish between the light from the sun that it has relied on for millenia and the light from phones which developed in the past fifty years. When our brains perceive light, melatonin production in the pineal gland is suppressed and we remain awake. Our eyes serve as the interface through which the brain interacts with the world to understand how it should direct resources and modulate our activity. When we introduce phones to our routine right before going to bed, the brain can’t simply allow us to easily transition into sleep – we’ve already triggered the primitive pathways responsible for keeping us awake. 

With many people feeling an overwhelming need to scroll through social media right before they sleep – just one more surge of dopamine for the day – masses of adolescents and adults face chronic dysregulation of their circadian rhythms. 

When you don’t rest enough, your body is forced to release cortisol to keep you awake and functioning. Your blood pressure never has a chance to climb down, your heart beats overtime, and the chemical signals in your body that regulate hunger become dysregulated so that there are insufficient levels of leptin to suppress hunger and excessive levels of ghrelin to induce hunger.  

The result of chronic sleep deprivation, according to longitudinal studies, is thus depression, obesity, atherosclerosis, anxiety, hypertension, and greater risk for cardiovascular disease. Yet again, we find the same chronic illnesses serving as symptoms of a greater problem of evolutionary mismatch, our bodies’ responses to an abnormal environment.

However, it isn’t a hopeless situation. Not at all. 

Many people think the key to health and success in life is a series of grand changes – running marathons, growing your own vegetables, spending two hours every day to prepare gourmet meals with fourty-eight different ingreidents. That isn’t the case. A healthy lifestyle is a series of small good choices made consistently over a long period of time. 

We could all benefit from finding ways to incorporate small bouts of movement into the day, choosing to schedule our last use of social media so that there’s a wider gap before bed, and re-allocating some of our money for fast food options or suary treats to fruits for snacks. 

Through small changes, we can slowly bring our bodies back into equilibrium and back to life. 

– Danielle 

References:

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