Chapter 1: Understanding Behavioral Genetics

The argument for the genetic basis of our behaviors has never been more compelling. Historically, the impact of environmental factors has often been exaggerated. It turns out that the effects of parenting can frequently be traced back to the genetic traits inherited from parents or children; in other words, intelligent parents may not inherently produce more intelligent offspring; rather, they pass on their genetic predisposition for intelligence.

Interestingly, there are even genetic components that influence the environments we gravitate towards. If socio-economic status is linked to genetic factors (as intelligence is significantly heritable), how can we classify this as purely environmental?

The variance in behavior—what distinguishes an individual from others—is how researchers assess the roles of genetics, environment, and parenting in determining life outcomes. Approximately 50% of this variance can be attributed to genetic factors. Notably, even the traits we value most, such as IQ and personality, are influenced by genes to the same extent. However, these measures of variance are purely descriptive; they illustrate the situation within a specific population but do not imply that different scenarios are impossible. Nevertheless, this does not undermine the hypothesis that genetics have a substantial impact on various life outcomes. But what accounts for the remaining 50% of variance?

Perhaps chaos plays a role. Consider how your body generates capillaries that are only a few cells away from any skin cell. Is there a specific gene that determines the location of each cell? Since the number of genes is insufficient to encode such information, how is this achieved? Blood vessels adhere to simple rules that dictate when they should branch out. These rules are generally scale-free, meaning they apply universally from large arteries down to tiny capillaries. In fact, these rules could easily be scribbled on a napkin; they are straightforward yet quickly lead to seemingly random outcomes.

This video, "How Do Genes Influence Our Behaviour? - Robert Plomin | Modern Wisdom Podcast 353," delves into the intricate relationship between genetics and behavior, offering insights into the ongoing debate surrounding the influence of genes on our actions and decisions.

Section 1.1: The Unpredictability of Chaos

Why is weather notoriously difficult to predict? We possess a solid understanding of how pressure, temperature, and other factors interact at the atomic level. So where does the unpredictability stem from? Non-linear systems create challenges for reductionism—the idea that understanding the individual components will lead to an understanding of the whole. For instance, can we comprehend traffic simply by studying internal combustion engines? The answer is no.

Even if we were to deploy sensors across every inch of the planet to monitor localized weather patterns, we would still lack sufficient data to accurately forecast every aspect. This is due to minor fluctuations in local conditions leading to unpredictable results (often referred to as the butterfly effect).

Subsection 1.1.1: The Nature of Non-linear Systems

When you toss a ball into the air, the outcome is predictable; it’s a linear system where more force translates directly to increased height. In contrast, non-linear systems operate differently—a minor disturbance can lead to significant effects. This contradicts the conventional understanding of cause and effect. For example, if we know the force needed to propel a ball 25 feet into the air and we inadvertently add a tiny bit more force, the outcome could be an astonishing 75 feet, far exceeding our expectations. Biological systems, like the brain, exhibit non-linear behavior. Modern mathematics often simplifies non-linear systems into linear approximations because they are easier to analyze.

“The most thrilling phrase to hear in science, the one that heralds new discoveries, is not ‘Eureka!’ but ‘That’s funny …’”

— Isaac Asimov

In a well-known simulation, mathematician Edward Lorenz attempted to model the weather through non-linear equations. While entering data, he rounded the figure 0.506127 to 0.506, which dramatically altered the results, demonstrating sensitivity to initial conditions. A tiny adjustment led to considerable divergence in outcomes.

Chapter 2: The Quest for Determinism Amidst Chaos

Can deterministic rules exist in biology that govern the brain and, consequently, our behavior? If such laws exist, they could challenge the concept of free will. Just because non-linear rules are elusive does not imply that they are absent—though the burden of proof lies with those who deny the existence of free will. The complexity of non-linear systems does not render them ultimately unpredictable.

Many philosophers who reject the idea of free will remain unfazed by the potential discovery of such underlying equations. Ironically, they wouldn't have the option to feel worried if deterministic rules for the brain were proven true. Advocates of free will argue that causality can flow in reverse; consciousness may influence brain states, which in turn affect future consciousness states. Could this suggest that consciousness has the ability to assert its freedom? This notion remains questionable. When probing how consciousness can alter its brain state, we often find that this capability has already been shaped by previous brain states.

For instance, if you consciously opt to get more sleep on a particular night, you will likely wake up more refreshed and able to think clearly. If you lack the willpower to follow through, you simply won't. Our consciousness isn’t infinitely free to modify the brain; there are objective facts about the brain, including the extent of one's willpower—a subject that has garnered some attention in literature, albeit not extensively.

In the future, we may uncover the order hidden within the chaos of the human brain and realize that nothing happens by chance; everything has always been deliberate and will continue to be so.

“Somehow, as the universe moves toward its ultimate equilibrium in the featureless heat bath of maximum entropy, it manages to generate fascinating structures.”

— James Gleick, Chaos: Making a New Science