[ This is post #5 in the series, “Finding reality in a post truth world.” ]
In Part 1 on this subject, I looked at the vision system as a demonstration of Donald Hoffman’s FBT (Fitness Beats Truth) theorem. In this part, I’ll look at some of the other senses – touch, hearing, smell, and taste. Given the shortfalls of vision, a pure anthropomorphist can only hope that these senses would make up for the deficiencies.
Smell: most of us are under no illusions about our inferiority in this realm. Even ancient hunters probably knew the game they were hunting had far better scent detection than they did. Black bears, with noses 100 times as big as ours, can smell anywhere from 2 to 20 miles, depending on which expert you’re asking. Polar bears can smell through a meter of ice, which helps them keep alive in the cold Arctic.
Does “Fitness Beats Truth” (FBT) apply here? Yes. We are not solitary creatures like bears. In our case, this sense is much more bound up with social interactions. Our sense of smell is also closely linked with disgust, which protects us from parasites and pathogens.
Touch: touch receptors in our skin make us aware of heat, cold, pressure, and texture. Again, our sense pales in comparison with cephalopods, in particular octopuses. The typical octopus has around 500 million neurons in its body, comparable to that of a dog. The difference is that most of their neurons are in their arms. This is what allows them to blend in with their environment in an uncanny way.
Our sense of touch doesn’t compare to that of a cephalopod, but it’s quite enough to allow us to prosper in our environment. We don’t live on the sea floor, where we have to change our camouflage to blend in with every aspect of our environment.
Hearing: Just as with vision, our hearing is limited to a smaller portion of the sound spectrum. We can’t perceive ultrasound like bats and dolphins. Nor can we sense infrasound (extremely low pitch sounds) like elephants, whales, giraffes, and alligators. FBT gives us sharp enough hearing to discern close predators, but it especially is attuned to human to human speech.
Given our somewhat pathetic sensory abilities in comparison to other members of the animal kingdom, we might wonder how in the world we could survive, in a Darwinian sense. FBT is one thing, but it won’t save you if a grizzly bear is reacting to your attempt to take a selfie with her cubs. The answer lies in the complex chemistry and anatomy of the brain. Sensory inputs don’t just go to the amygdala; they also go to the hippocampus and prefrontal cortex.
Without getting into an anatomy lesson (which I’m unqualified to give anyway), the amygdala processes memory, decision-making and emotional responses. This is a great oversimplification, of course, but researchers have discovered that the amygdala has a significant effect on sexual orientation, social interaction, aggression, fear, and anxiety. The prefrontal cortex, on the other hand, plays an active role in higher level decision making, planning, making friends, and emotional modification. Both the prefrontal cortex and the amygdala take in stimuli from the sense organs, but they process these in decidedly different ways.
Humans are not the only animals with a prefrontal cortex, but research suggests that it is unique. Yes, it is relatively large in size, but its organization also differs from other high level primates. All this suggests that the human prefrontal cortex is the evolutionary factor that allowed homo sapiens not only to prosper, but to become the dominant species on the planet, despite limited direct sensory abilities.
Just watch a child develop, and it’s clear there are two ways to respond to sensory stimuli: instinctive and direct vs. planned and contemplative. In the early years, the brain takes in millions of scenarios and puts together virtually automatic responses to various situations. If a small child puts their hand on an active stovetop, the brain doesn’t “think” about a strategy. The child immediately withdraws her hand and probably yelps.
The same sort of thing happens when a baby who has bonded with parents is handed off to a stranger. Anxiety and tears are often immediate. Again, this isn’t a result of the prefrontal cortex analyzing probabilities that the stranger is friend or foe. It’s an immediate response based on a simple truth: parents = good; strangers = bad.
As the child grows into an adult, the prefrontal cortex modulates this behavior. A different system takes over, one that evaluates probabilities (perhaps poorly) and consequences. Many senior citizens wonder how they even survived their teens and early twenties, when they engaged in reckless, life-threatening behavior with no thought about outcomes. This is a direct reflection of the immaturity of the prefrontal cortex at that age.
The existence of two systems of thought and action may seem obvious when we think about it, but it is only in the last few decades that we have started analyzing how these systems interact with each other and how the dominance of one over the other might lead to bad results.
Historically, we have been so proud as a species of our superior prefrontal cortex thinking that we assumed it dominated everything, and that impulsive thinking was simply an artifact of immaturity. In my MBA program, the Chicago school of economics was the de facto standard. This assumes that people are rational actors who make economic choices that maximize utility.
Daniel Kahneman and Vernon Smith were awarded the Nobel Prize in economics for work in 2002 that disproved that notion. In 2011, Daniel Kahneman published Thinking, Fast and Slow, which summarized his work over the course of decades. In particular this work delineates the difference between the impulsive systems of the brain, which he calls System 1, and the deliberative, thoughtful system of the brain, System 2. This analysis is a necessity if we want to understand the basis of cognitive and logical fallacies, and especially what to do about them.
The next few posts will be devoted to a discussion of these two systems, based on Kahneman’s book.