Theology and Evolutionary Psychology, Chapter 2: On the Sweet Tooth, Snakes, the Magic Moral Number 150, and Weight Watchers for Love

After two posts setting the stage (Faith vs. Science and Evolution 101), it is time to approach evolutionary psychology.

The basic premises of evolutionary psychology are easy to state:

1.The brain is not simply a generalized learning device (although it has these kinds of non-domain specific capabilities). Rather, the brain possesses distinct information-processing biases (cognitive tendencies) that are the product of evolutionary pressures.

2.That is, the brain has an adaptive architecture, shaped by cognitive adaptations to meet adaptive challenges in the ancestral environment.

3.The ancestral environment was the environmental situation during which most of brain evolution occurred (3.5 million years ago until about 10,000 years ago, the end of the Pleistocene era).

4.Thus, the modern human brain reflects the cognitive tendencies that were adaptive in the ancestral environment.

All these premises seem plausible. That is, while the brain was rapidly expanding and evolving it seems reasonable that certain cognitive and behavioral tendencies would have been selected and passed on if they proved adaptive.

What this means is that the brain is a bit like a time capsule, a window on the past. What did this past look like? Well, basically the brain has spent 99% of its history in hunting-gathering-fishing (HGF) cultures. When we speak, then, of the ancestral environment we are speaking of the HGF cultures that existed from 3.5 million years ago until about 10,000 years ago.

For evolutionary psychologists, then, the key to unlocking the mysteries of the brain is to engage in some reverse engineering. That is, we seek to specify the unique adaptive challenges in HGF cultures to locate correlated mental adaptations present in modern brains.

One interesting way to look for these Stone Age tendencies is to look for adaptive “mismatches.” These adaptive mismatches are mental biases that are clearly maladaptive in the modern context but were extraordinarily adaptive in the ancestral environment. This mismatch is easy to explain. Natural selection moves very slowly. But cultural evolution, once it gets started, grows explosively. Thus, over the last 10,000 years cultural evolution (largely due to the technological revolution) rapidly changed the adaptive situation surrounding the brain, outrunning natural selection’s ability to keep up by many orders of magnitude. Basically, we have Stone Age Brains in a Space Age World.

This might seem farfetched so let me give some examples, the last of which goes to issues of theology and ethics.

Example #1: Our Sweet Tooth
Does it ever strike you as odd that God did not equip us with food-preferences that perfectly correlated with the FDA food pyramid? Would not that have been the optimal design? So, why don’t we innately crave the foods that are good for our health and well-being? Why don’t we say, “Johnny! Stop eating your peas and eat some more cake!”?

Well, the issue becomes clear when we look at the situation the way an evolutionary psychologist would. Specifically, sugars and fats are high-energy foods. But in HGF cultures these foods are relatively rare. The HGF diet is rich in nuts, grains, and plants, but poor in sugar and fat. Now imagine a vegetarian in the HGF ancestral environment. Or someone shunning sugars because they want to watch their figure. How will these people fare, adaptively speaking, compared to those who craved and sought out these rare but high-energy food sources? The guess is not very well. In short, our sweet tooth is a cognitive adaptation, an innate bias, which makes sense in the ancestral environment. But cultural evolution has overrun that mental bias, filling our world with cakes, cookies, candy, and sugary drinks. Fats and sugars, once very rare and thus craved, are now common. The sweet tooth, once a beautiful adaptation, is now our burden. And obesity becomes epidemic.

Example #2: Why Cars and Guns Don’t Cause Panic Attacks
The #1 leading class of phobias is small animal phobia: Spiders, snakes, bugs, mice, etc. Why is this? I routinely ask my classes these questions:

1.Raise your hand if you are afraid of snakes. (Many hands go up. My own included.)

2.Great. For those of you who are afraid of snakes keep your hands up. Now, if you hand is up, put it down if you’ve ever been bitten by a snake. (No hands go down.)

3.Great. Keep your hands up. Now, put it down if you’ve actually SEEN a snake in the wild. (A few hands go down, but most stay up.)

Why this crazy response? Many people are deeply afraid of snakes even though they have no personal learning history with snakes (e.g., been bitten). More strangely, many people are afraid of snakes and yet they have never even SEEN a snake it a natural habitat. What is going on? Well, I go on to ask these questions:

1.How many of you are afraid of cars? (No hands go up.)

2.How many of you are afraid of slick bathtubs? (No hands go up.)

The point here is that we are all much more likely to be hurt in car accidents or from slipping in the bathroom than from snakebite. So why don’t our phobia acquisition patterns reflect the REAL dangers in life?

Well, and I bet you can guess the answer, cars and bathtubs just weren’t around in the ancestral environment. Our brains just don’t have an adaptive history with these things. Like the sweet tooth, our innate skittishness in response to certain stimuli, which was once adaptive, was overrun by modern dangers. That is, although there were no cars, guns, or bathtubs in the ancestral environment, there were poisonous insects, snakes and disease-bearing rodents. And those who possessed more of a natural reticence to handle these animals (“Johnny! Put that cobra down and come to dinner! Johnny? Johnny?”) were more likely to pass on their reticence. We are their skittish children.

Example #3: The Magic Moral Number 150
This last example has a more serious application to theology and ethics. HGF societies were small. Without established farming HGF cultures could not create food surpluses and mobility was important. Thus, these cultures were small. How small? Well, the best estimates place the number around 150. That is, most of brain evolution appeared to have taken place in small, kinship-bond groups of about 150.

Interestingly, when we analyze the family/friend lists of modern persons we get numbers of around 150. That is, your current “clan,” those to whom you instinctively extend familial affection (even if they are not biological relatives), is about 150.

These two data points seem to suggest that our brain’s “little black book” for family and friends appears to have only 150 entries available.

What does this mean? It means that we see the world very locally. This means that we have trouble seeing most of the people in the world as worthy of moral attention. We focus most of our time, energy, and effort on about 150 people.

Like the sweet tooth, this ancient cognitive bias (i.e., our mental “black book” got set at 150 entries) is having disastrous consequences on modern living. Racism. Xenophobia. Gated communities. Prejudice. The movie Crash. On and on we see the toll of this bias.

Obviously, Jesus calls us to love everyone. To not just greet “brother and sister.” But we are fighting against human nature. And we need to be prepared for just how hard this battle will be. Personally, I don’t think churches are doing enough in this area. I think they are underestimating just how much resistance human nature is putting up. And thus churches are failing on a wide scale.

Let me put it this way. Compare the Magic Moral Number 150 to the sweet tooth. Now ask yourself, how hard is it to eat healthy or lose weight? How many failures do you experience with diet and eating? Lots I bet.

Well, loving the world is just like that. It’s like trying to stay away from the ice-cream or lose 20 pounds.

So let me ask you this. If loving the world is like losing 20 pounds, are churches putting intensive programs into place akin to Weight Watchers? Is there intensive coaching, accountability, and weigh-ins EVERY WEEK? Because this is what it is going to take.

A Weight Watchers for love.

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12 thoughts on “Theology and Evolutionary Psychology, Chapter 2: On the Sweet Tooth, Snakes, the Magic Moral Number 150, and Weight Watchers for Love”

  1. Richard, our minds evolving/adapting to our environment (and perhaps lagging behind cultural changes in the modern world) certainly seems to be a cogent idea. But given the theory's apparent validity, how do you respond to someone who would assert that a belief in God is merely leftover Stone Age thinking and that perhaps atheism is an adaption to a modern understanding of the world?

  2. Hi Jason,
    People are certainly making that argument and I might review some of those ideas in this series.

    Here's my take: I think the God Question is independent of human cognitive evolution. Evolution may bias us toward or away from belief in God. But that trajectory seems independent of the status of God’s existence. I think most theologians quickly make this point to reductive evolutionary scientists of the mind (e.g., Richard Dawkins).

    That said, as a psychologist, I deeply feel that evolutionary psychology can tell us lots about HOW we think about God. That is, evolutionary history may bias us toward thinking of a certain KIND of God. This is just a different way of saying we are prone to creating God in our own image. I'm just tracing some of that impulse back to the cognitive (and not just the social/cultural) level. Phrased yet another way, I think we have theological "sweet tooths," cognitive grooves that routinely capture our thinking, even the thinking of our very best theologians. To combat this, we can educate ourselves about our minds so we can overcome these mental grooves (like our real sweet tooths). Even theology, that most abstract of endeavors, must still work to transcend biology.

    (PS-Sweet teeth just doesn’t sound right to me. As in the Lord of the Rings, Chapter 1, The Long Expected Party: Is it Proud Foots or Proud Feet?)

  3. Completely irrelevant, but I developed a device a long time ago to aid with the sweet tooth paradox:

    It's called the Gustatory Bypass Apparatus.

    Foods that taste good but are unhealthy go in the mouth, but not the digestive system. Foods that are healthy, but taste bad, are somehow introduced into the digestive system.

    I think some sort of cravat is needed to cover up the messy tubes...h

  4. Yes, I've been wondering where this desire to single-handedly populate a small town was coming from.


    Excellent ideas on evolutionary psychology and evolution but I would like to oppose a bit as far as the fear of cars is concerned. Your question was not a proper one, or the people did not tell the truth.

    Drivers are afraid of cars, but not of sedans, they are afraid of huge trucks. This fear of huge trucks is bigger in females than males, though even males are afraid of huge trucks sometimes.

    The reason here is also evolutionary one and one of the absolutely basic reasons for fear: the size and the speed. Because we all the biological organisms live according to pattern “eat or be eaten” and “fight or flight”, the size of something approaching plus the speed of approaching was a good signal for “fight or flight”.

    The size of huge truck makes some people feel the fear of it, and this fear was developed as a warning signal, because if something is bigger than me I should flee and if it can develop higher speed than I can I am really in bad trouble.

    Think of this - most probably first –warning signals which are size and speed, and therefore when people say they are not afraid of cars, they do not say the full truth.

  6. I had some problems in posting my comment here so fear of cars was written by borek 123456

  7. Nurture is a contributing factor to the snake fear as well. Whenever little kids learn about animals in school (and probably from their parents), they learn snakes may be poisonous. In popular culture, particularly in movies, snakes are depicted as dangerous, life-threatening creatures.

  8. Jason,
    I would also say that learning about guns and cars (i.e., crossing the street) are the same way if not more so. Yet, phobic responses are harder to acquire for those stimuli. One must admit that the disjoint is odd.

  9. I agree with you. I was just saying that snake phobia (as plenty of other behaviors) has some nurture mixed in with nature.

    I also think another contributing factor is the lack of exposure to snakes for most people. For example, I suppose some people's fear of flying stems from a fear of heights, but certainly the thought of "I could die in a plane crash" is the primary factor. Conversely, not many people are afraid to ride in cars. Why, especially since you're much more likely to die in a car crash? I'd suggest it has something to do with how often we ride in cars compared to how often we ride in planes.

  10. If New Yorkers are "permeable" as one character in Shortbus suggests, then perhaps this means that for those of us who grew up near/in big cities, we have learned to work around this constant, (because we have to), not by trying to increase this number, but just by being that, "permeable", and having a shorter monte-carlo improv-chain mixing-time, knowing that those in the Magic 150 will sometimes come and sometimes go, and shift like grainy waves in time.


  11. it seems to me the dysfunction of religion is why the earth is in the crappy mess it is in.... not our love of oil or nukes.... the stupid belief that another ..(lesser/greater)..power will step in and save our ravaged is silly to think we might go to a better place.....

    making our here now the best place we can be right about those around you...and let the "god" through us... not for us............anyhow....reincarnation or freedom of the shackles of an uncaring super-entity are the more absolutes.....face it.... we are not out of the gravity .........yet

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