Charles Darwin Can Shed Light on Human Health

charles darwin, science, human health, health
Charles Darwin scarcely mentioned the evolution of the human race in his infamous work On the Origin of Species, excluding one neatly tucked away sentence, “Light will be thrown on the origins of man.” Since the Origin was first published more than 150 years ago, light has not just been thrown on man, but cast in illuminating detail. Given that health falls within the biological domain of science and everyone’s resolution’s is to stay fit, Charles Darwin can shed light on human health.

Diabetes, cardiovascular disease, obesity, high-blood pressure and cancer are some of the most common illnesses to plague the American population and are largely tied to an industrialized diet. These illnesses are shinning examples of what is known as “mismatch diseases.” Mismatch diseases are illnesses that are the corollary of consuming large amounts of food that the body is inadequately adapted to sufficiently digesting.

The origins of humanity make their way back to the African Savannah where meat was scarce and fruits and vegetables were abundant. Cavemen, whatever that term might mean, did not have diabetes. Unlike maladies that spread from one host to the next within a population, diabetes, as with all mismatch diseases, are cultural diseases. With the rise of industrial agriculture, sugar was readily refined, packaged and distributed at an affordable price. The ability to intentionally manipulate the environment to our own needs has led to unintended consequences.

It is only recently that the term “hunter-gatherer” has been used to describe a sport rather than a way of life. To revert back to the theme of sugar, the sweetest of treats was honey for hunter-gatherers and was a scarce luxury. Rather, fruits and vegetables were a common entree and meat tended to be a side dish. While much sugar can be extrapolated from fruits, the kind of sugar consumed by hunter-gatherers was strikingly different. Unlike the refined sugar of today, the sugar found in fruits is bound inside cells that contain lots of nutrients which are essential to a healthy diet. It is quite surprising how bitter most wild fruits actually are.

Since the human body evolved in a terrain where sugar was scarce, it did not adapt to digest the amount of sugar that is now readily available. Diabetes is an exact consequence of high sugar consumption. Blood sugar levels increase because the body’s cells are incapable of digesting the amount of sweets consumed. It should therefore be unsurprising that diabetes is a recent illness on the rise in America, India and China, since during the paleolithic era, the average amount of sugar consumed a year per person was four to six pounds. The average American today consumes 100 pounds of sugar per year.

Many sugar substitutes, such as Splenda and Total, have been manufactured in order to quench the human desire for sweets at the cost of fewer calories. Yet the reasoning behind sugar substitutes has expressed rather than suppressed the modern-day sweet tooth. Like any food, sugar is digested in the stomach. The nutrients in the food are broken down and absorbed into the bloodstream where metabolism takes place. Metabolism is a process in which the body’s cells convert the nutrients absorbed by the bloodstream into energy. It is unclear whether artificial sweeteners are an effective substitute for sugar since the stomach’s digestive system is sensitive to change. As a result, metabolic processes cannot efficiently extrapolate enough energy from artificial sweeteners, which decreases blood sugar levels and in turn, makes the body crave real sugar all the more.

To continue upon the theme of sugar, the phenomena of “comfort food”—intense cravings for sweet and fatty foods during episodes of stress—begin to make sense once we consider how Charles Darwin can shed light on human health. In particular, the stress of today is not the stress of yesterday. Our ancestors lived in an environment where intense episodes of stress were short-lived and tended to occur when trying to outrun a cheetah or lion. During these short-lived episodes of stress, the body goes into a fight or flight mode—both of which require lots of energy. As a result, the hormone cortisol is activated. Cortisol is a hormone that unleashes large amounts of stored sugar into the bloodstream. When activated, it exhausts the body’s energy supply in a single flush. As a result, the body craves sugar and fat in order to compensate for the energy lost. The problem is that, unlike our ancestors, the stress today is not short-lived, but occurs regularly throughout the day usually behind the dormitory passivity of an office desk rather than say, outrunning a lion. As a result, the body’s energy is not exhausted yet continues to crave sweets regardless.

Charles Darwin and his theory of evolution have stood the test of time and continue to shed light on many scientific domains, from genetics to psychology. By viewing the human body within a proper biological frame, evolution by means of natural selection as purported by Charles Darwin can shed light on human health. While citizens are ill-advised to go to an evolutionary biologist to treat a particular malady, a proper understanding of the human body seen through the lens of Charles Darwin can serve as a compass for dieters throughout 2014.

By Nathan Cranford


Washington Post
Harvard Magazine