Is Outdated Behavioral Code to Blame for Unhealthy Living Habits?

Notwithstanding the well known danger and the clear evidence that healthy living habits significantly reduces the risk, many Americans choose to live lifestyles that put them at high risk of suffering from heart disease. To explain this seemingly irrational human behavior let’s take a look at how evolution has coded humans to behave.

codeevoThe leading cause of death in the United States is heart disease.   In fact the average American stands a 1 in 3 chance of dying from heart disease.   Advances in medical technology cannot offset the increasingly poor lifestyle that American’s lead.  Most people are familiar with the most often cited measures for decreasing the risk of heart disease, mainly:


1.       Don’t smoke

2.       Be active

3.       Eat healthy

Notwithstanding the well known danger and the clear evidence that healthy living habits significantly reduces the risk, many Americans choose to live lifestyles that put them at high risk of suffering from heart disease.   To explain this seemingly irrational human behavior let’s take a look at how evolution has coded humans to behave.

Humans are Coded to Desire Certain Types of Foods

In the primitive years of humankind, food was scarce and in order to get it people had to go out and forage, gather or hunt.  Further, certain foods were more abundant or easier to obtain than others.  Green leafy plants were more abundant that juicy fruits.  Meat required substantially greater effort to acquire than plant based foods.  So, why didn’t we just eat leaves all day?

Fruits, while less abundant than green leafy plants, have high caloric content.  And since this caloric content gave the people who ate them more energy, people who craved their sweet taste enough to work to find and gather them had a survival advantage.

Similarly, meat, while requiring considerable effort to obtain, has relatively high protein content.  And since this protein content gave the people that ate meat stronger bodies, people who craved meat enough to hunt for it had a survival advantage.

Evolution eventually coded people to crave sweet fruits and meat enough to put in the hard work to find those foods and use them as a supplement to their diet.

Humans are Coded to Minimize Physical Activity

Basic survival in primitive times required substantial physical effort.  Food had to be hunted for or gathered.  Other basic survival requirements, such as finding water and not being eating by other animals, required constant physical effort.  In a time when food was scarce it was important to conserve caloric expenditure.  People who wasted physically energy needlessly exhausted their bodies and were less likely to have energy to find more food and more likely to be susceptible to starvation or disease.  Thus, people who had a desire to minimize physical activity also had a survival advantage.

Evolution thus coded people to:

1.       Crave sweet fruits and meat

2.       Minimize physical activity

The Primitive Natural Balance

The desires of primitive people were curtailed by the reality of the time.  While they craved fruit and meat, the scarcity of these foods curtailed overconsumption of them.  And while they desired to reduce physical activity, a certain amount of activity was necessary to find food and survive.  In fact, primitive humans had to evolve a very strong desire for scarce foods in order to have the will to overcome the natural obstacles to obtaining those foods.  Similarly, they had to evolve a strong desire for inactivity in order to seek rest in a time when basic survival required such constant strenuous effort.  But the natural order of the primitive world provided a balance that prevented humans from over consuming certain foods or wasting away in lethargy.

The Modern World

Human technology has evolved rapidly since those primitive times and the world we live in is entirely different.  Sweets and meat are readily available in large quantities.  And our lifestyles afford us the luxury of surviving just fine with de minimis physical activity.  But evolution progresses slower than advances in human technology and has thus not yet coded us to survive in our modern world.  Our current code for food and activity preferences is in many ways unchanged from the one that is eons old and is arguably ill suited for modern life.  Our evolutionary desire for sweets and meats, virtually unchecked by any scarcity of these foods, causes us to over consume these foods.  And our evolutionarily coded desire to minimize physical activity, in the absence of any survival requirement to be active, causes us to lead sedentary lifestyles.

It is healthy for us to eat meats and sugars in reasonable quantities.  But it is important for us to recognize that our natural craving for these foods exceeds our body’s need for them.  And over consumed they become harmful.  Similarly, rest and relaxation is an important part of human health.  But absent some natural force demanding that we be active, we must resist the urge for constant sedentariness and give our bodies a healthy amount of physical activity.

The modern world provides us the tools to lead substantially healthier and safer lives than our primitive counterparts.  Healthy foods are regularly available.  And our understanding of nutrition has allowed us to engineer foods that are superior to anything that our primitive counterparts had available to them. Vitamins, healthy carbohydrates and fats and proteins are all easy to obtain and consume in healthy doses.   It is up to us to (1) recognize that our desires to over consume certain foods and lead inactive lifestyles are to some large extent the result of outdated evolutionary code and (2) learn to curb those desires in favor of healthy living habits.


http://www.cdc.gov/nchs/FASTATS/lcod.htm


http://www.americanheart.org/presenter.jhtml?identifier=3035374

For the purpose of this discussion I am going to ignore smoking.  While the human desire to smoke is certainly interesting and complex, I think it stems from a different category of humans traits than I wish to discuss here.

I am certainly simplifying the categories of foods that humans desire.  I am also simplifying the nutritional value of these foods.  In reality the set of human needs and preferences for foods is much more complex.  But for the sake of discussion I will stick with these simple examples.

Even relatively simple foods such as a mixed salad or a bowl of bran flakes with a glass of orange juice are substantially more sophisticated than anything that was available to primitive humans.

Leave a Reply

Your email address will not be published. Required fields are marked *