Heuristics Basics

Hunter Gatherer Notes

Why we struggle to make logical decisions

Our clean, square, and climate-controlled environments may be impairing our abilities to distinguish certain visual input, such as knowing that the illusion of two identical sized lines with opposing arrow heads are in fact the same size. Alternatively, we can think of this deficit as an adaptation to our environment rather than a loss. This unnatural symmetry has restructured our WEIRD brains.

Lactose is apparently a functional substitute for vitamin D in promoting the uptake of calcium, which is rare at the poles. Among the desert people, being able to digest milk allowed them to avoid dehydration. Lactase persistence was born of a particular environmental condition, which moved onto a genetic layer.

The false nature versus nurture dichotomy is disruptive, as it interferes with a more nuanced understanding of what we are and the evolutionary forces that have brought us here. The change in susceptibility to optical illusions seen in WEIRD countries is no less evolutionary than the change in ability to digest dairy in European and Bedouin peoples. The latter has a genetic component, and we have no reason to think that the first one does. Yet they are both equally evolutionary.

Carpentered corners create greater susceptibility to certain optical illusions. Overreliance on chairs creates all manner of negative health outcomes. What, then, might deodorants and perfumes have done to our ability to smell the signals emitted by our bodies? What might clocks have done to our sense of time? What have airplanes done to our sense of space, or the internet to our sense of competence? What have maps done to our sense of direction, or schools to our sense of family?

Adaptation and Chesterton’s Fence

Three-part Test of Adaptation

If a trait

• 1. is complex,
• 2. has energetic or material costs, which vary between individuals, and
• 3. has persistence over evolutionary time,

then it is presumed to be an adaptation.

This model can produce false negatives, but not false positives. Revealing the sufficient, but not necessary evidence that something is an adaptation. There will always be exceptions, such as the loss of pigment in a polar bear’s fur or the loss of hair on a naked mole rat, but this is due to energy cost saving.

Let’s try the test on the human appendix.

• The appendix, which is found in a smattering of mammals, including some primates, rodents, and rabbits, is an outpouching from the large intestine, and it harbors intestinal microorganisms with which we are in a mutualistic relationship. From us, those intestinal flora get room and board; from them, we get the ability to repel infectious disease, and are facilitated in digestion and the development of our immune system.
• Furthermore, the appendix is not made of the same material as the surrounding gut—it contains immune tissue.
• Is it complex? Check. It also takes energetic and physical resources to grow and maintain, and has variation in size and capacity both between individuals and between species (check). Finally, it has a history, in mammals, that is more than fifty million years old (check).
• The human appendix, therefore, is presumably an adaptation. We just don’t know what it is an adaptation for.
• Possibly to repopulate the gut with mutualistic gut flora after a purging of gastrointestinal illness with diarrhea. In the non-WEIRD world, diarrhea is common and a significant cause of mortality. Appendicitis, on the other hand, is almost unknown to those non-WEIRD countries. It is a disorder of the WEIRD world. Just like many allergies and autoimmune disorders.

The hygiene hypothesis posits that because we live in ever-cleaner surroundings, and are therefore exposed to ever fewer microorganisms, our immune systems are inadequately prepared, and so develop regulatory problems, such as allergies, autoimmune disorders, and perhaps even some cancers. Our immune systems are not functioning as they evolved to do because we have cleansed our environments too thoroughly.

If we can’t see the use of something, we should not clear it away until we know of its function.

Trade-offs

Broadly speaking, there are two types of trade-offs:

• Allocation trade-off: Because many things in biology are zero-sum (there are a finite number of resources), something has got to give.
• Design-constraint: These are insensitive to supplementation. Meaning, you can’t just add more of something to solve a problem. In the example of a bat, you can either specialize in flying fast or flying agile, or be a generalist.

Humans have avoided this trap by building outside of ourselves. We are a broadly generalist species, with the capacity for individuals—and cultures—to go deep and specialize in myriad contexts and skill sets.

But for all of our cleverness, we can’t evade all trade-offs. Presuming that we can is one mistake of Cornucopianism, which imagines a world so full of both resource and human ingenuity that, magically, trade-offs no longer rule. Related to Cornucopianism, or perhaps fueling it, is the fact that the Sucker’s Folly can create the illusion that we have conquered trade-offs by blinding us with the richness and opulence of our short-term gains. This is a mirage. The trade-offs are still there, and the cost for all that wealth will be paid, either by those who live elsewhere or by our descendants.

Trade-offs are unavoidable, but this has a remarkable upside: it drives the evolution of diversity.

• Photosynthesis, the process by which plants convert sunlight into sugar, occurs in the vast majority of plants in a form known as C3. C3 works best under conditions that are easy for plants—moderate temperatures and sunlight, and ample water. Because C3 photosynthesis requires that the pores on the leaves—the stomata, which allow intake of carbon dioxide—be open at the same time that sunlight is fueling photosynthesis, C3 photosynthesis comes at the cost of substantial water loss through the stomata. C3 plants, therefore, don’t do well where water is limited.
• As plants began moving into more marginal environments, such as deserts, C3 photosynthesis posed a particular problem, and two new forms of photosynthesis evolved. One of them is CAM photosynthesis, which allows plants to separate in time when they open their stomata to take in carbon dioxide from when sunlight is fueling their photosynthesis. Having their stomata open at night, when temperatures and therefore evaporative loss are lower, allows CAM plants, like cacti and orchids, to conserve water.
• CAM is more metabolically expensive to accomplish than C3 photosynthesis. But, in environments where sunlight is plentiful but water is not, CAM wins hands down against C3.
• As an organism decreases its surface area to volume ratio, becoming ever more sphere-like, the amount of water lost from its surface is reduced. More spherical cacti lose less water than long and lean cacti because they have less surface area relative to their volume from which to lose water.

Everyday Costs and Pleasures

We moderns have a hard time imagining the risks worth taking to find more food, the lengths one might reasonably go to protect what they have, and the value that might accompany technological innovations that allow people to stretch the value of food they have already acquired.

While we tend to think that the goal of cooking is to make food taste better, much of the world’s many culinary traditions have more practical goals—detoxifying foods, amplifying their nutritional value, and protecting them from microbial competitors as we carry them across space or preserve them over time. We salt and smoke meats to ensure that microorganisms that attempt to steal them will die of dehydration. We make fruit preserves with high concentrations of sugar for much the same reason. We pasteurize and freeze perishable vegetables to kill the microbes already on them and to exclude all newcomers.

Milk evolved to nourish babies straight from their mothers’ mammary glands. As such, milk is full of nutrients. But because milk is meant to be consumed immediately, with little or no contact with the outside world, milk has no defense against environmental bacteria, and we moderns must go to extreme lengths—pasteurization, hermetic sealing followed by refrigeration—just to preserve milk for a week or two. Clearly, an ancestor who needed to preserve milk over a long and unproductive winter would have needed a better solution.

• By rotting milk carefully, using specially cultivated bacteria and fungi that are not pathogenic to humans, milk can be preserved indefinitely. Cheese is such an elegant solution to the problem that, once made, even a block of cheese that is colonized by bad bacteria on the outside can have a thin layer of its surface removed to reveal the fresh, untainted cheese beneath.
• The catch is that humans are programmed to be repulsed by the smell of spoiled milk because, in general, it is a bad idea to consume any substance that has been overrun by microbes.
• We could tell a similar story about “thousand-year-old eggs,” sauerkraut, kimchi, or myriad other carefully preserved foodstuffs.

We are all born with basic rules of thumb about what we should and shouldn’t eat. A peach smells good. A clam that has been sitting in the sun smells bad. Grilled meat smells good. Carrion smells bad. These rules are an initial guess at the net value of a potential food, but if one stops there, then a lot of nutritious, edible things will be missed.

• There has evolved, therefore, a secondary system that allows us to remap foods according to empirical information that may be picked up from kin (via culture), or perhaps discovered in hunger-driven desperation (via consciousness). We are constantly remapping foods based on their actual value, rather than on our initial reactions. We may acquire a taste for coffee because it stimulates us, and for beer because it carries the nutrition of bread without the short shelf life.

Our long-evolved warning system—if it smells bad, be wary—is unreliable in two ways: (1) many solvents smell good to some people, and (2) smelling them is sufficient to cause physiological harm.

• Some truly toxic and otherwise dangerous substances encountered in the modern world have no detectable smell to them at all. Natural gas and propane are gases that have no smell we can detect, and each is capable of concentrating in ways that the tiniest spark can create a massive explosion.
• Before propane and natural gas are piped into your home, or delivered to a tank outside of it, they have tert-Butyl mercaptan added to them. This compound gives these otherwise stealthy gases a unique sulfurous smell—like dirty socks or rotten cabbage—that we easily recognize, and with guidance now find alarming.

Our detectors for CO2 are so ancient and deeply wired that even people with brain damage to the amygdala, such that they never panic under other fear-inducing circumstances, find themselves triggered into panic by high concentrations of CO2. By comparison with CO2, carbon monoxide (CO) is extremely dangerous: it binds to hemoglobin, displaces oxygen, and brings on a quiet sleep from which people do not wake. Why, then, do we have an internal detector for CO2, which is dangerous at high densities but nontoxic, but we don’t have a detector for carbon monoxide, a deadly toxin?

• A detector that causes an animal to become antsy, anxious, and in need of going elsewhere as their cave fills with CO2 is essential equipment. While it would be great to have a similar detector for carbon monoxide, that need is primarily modern, a consequence of industrial combustion. There is no reason to think that a CO detector would have been harder for natural selection to create, but the value of it is simply too recent to be in our hardware yet.

Smell is no longer a sufficient early warning system for hazards, because detection and harm are now simultaneous in many cases. We face novel levels of novelty, and selection simply can’t keep up.

The Corrective Lens

• Become skeptical of novel solutions to ancient problems, especially when that novelty will be difficult to reverse if you change your mind later. New and audacious technologies—from experimental surgery, to the cessation of human development using hormones, to nuclear fission—may be wonderful and risk-free. But chances are, there are hidden (and not-so-hidden) costs.
• Recognize the logic of trade-offs, and learn how to work with them. Division of labor allows human populations to beat trade-offs that individuals cannot. And by specializing in different habitats and niches, the human species beats trade-offs that no single population can.
• Become someone who recognizes patterns about yourself. Hack your habits and your physiology. What stimulates you to eat? To exercise? To check social media? Understanding the patterns in your behaviors gives you a better chance of controlling those behaviors.
• Look out for Chesterton’s fence and invoke the Precautionary principle when messing with ancestral systems. Remember this: “just because you can, doesn’t mean you should.”