The Genetics of Behavior
The science of how genetics impacts our good and worst behaviors.
In his book Behave: The Biology of Humans at Our Best and Worst, Robert Sapolsky does a fantastic job describing human behavior and the biological cause and effect that takes place leading to those behaviors. In his own words:
This book explores the biology of violence, aggression, and competition — the behaviors and the impulses behind them, the acts of individuals, groups, and states, and when these are bad or good things. … What does biology teach us about cooperation, affiliation, reconciliation, empathy, and altruism?
Sapolsky describes what part of the biological system is responsible for a behavior and in what time frame relative to the behavior occurrence:
- The Second Before: Nervous System
- Seconds to Minutes Before: Sensory Stimuli
- Hours to Days Before: Hormones that drive sensitivity to such stimuli
And the book goes even further back describing evolutionary traits and capabilities that drive our behaviors more fundamentally.
This book is packed with eye-opening summaries of brain research and interesting background stories and examples. It’s difficult to summarize such a dense book, but if you are looking for a quick tour, the TED talk shares some high points. In this article, I will aim to share three interesting observations, namely:
- Environment Drives Gene Expression
- The Biological Root of “Us vs. Them” Behaviors
- The Importance of Cognitive Awareness to be a “Good Person”
Environment Drives Gene Expression
I think one of the interesting detailed explanations throughout the book was that gene expression is substantially affected by environment. As stated nicely in the book: “genes are not autonomous agents commanding biological events” and “it’s not meaningful to ask what a gene does, just what it does in a particular environment.” I think there is a simplistic desire to believe that a particular gene simply drives a behavior — and the truth is much more complex.
One great example to illustrate is heritability (degree of variation as a function of genetics) of various aspects of cognitive development. The studies show that such cognitive heritability is very high (70%) for kids in high socioeconomic status (SES) but low (10%) for those in low SES. The environment of kids in low SES dominates cognitive development, whereas in high SES environments, genetics can play a larger role and influence. This intuitively makes sense — and validates the importance of the multi-lottery of being born into the right family, society, country.
To give an understanding of the level of scope and complexity in environmental expression of genes, the author explains transcription factors (TF) — the proteins that regulate genes. A large percentage of the human genome is transcription factors that enable the variety of gene expression and helps explain that while human and chimp share a 98% common genome, the expressions are very different as a function of these transcription factors. Numerically the author tries to highlight the scope and scale:
The human genome codes for about 1,500 different TFs, contains 4,000,000 TF-binding sites, and the average cell uses about 200,000 such sites to generate its distinctive gene-expression profile. This is boggling.
The bottom line here is that there are numerous environmental factors that play a strong role in shaping how genes are expressed.
“Us vs. Them” Behaviors have a Biological Root
One of the most challenging findings from the book for me was learning that we are biologically attuned to race — our amygdala in the limbic system lights up and kicks up fear/less empathy when we see someone of another race. This is deep in our evolutionary mind — and not something that takes place at the cognitive level, no matter what our feeling about race.
What was eye-opening here was the body of research that shows how this behavior take place unconsciously, automatically, and super fast — before we even have time to cognitively explicitly “think” about it. This finding is well supported including biological evidence of this behavior taking place in other primates and young children of all types.
What was encouraging here is that our prefrontal cortex (PFC) can cognitively overcome this intrinsic behavior. This tracks (hopefully) with what we know of our own reality and the goodness we see in the world. But it also explains why in certain environments, people will NOT be able to overcome their natural response through their cognitive functions.
There was a well-known study that shows that most laypeople will perform poorly on simulated tests when shooting an armed or disarmed white or black person — whereas police offers (regardless of bias) will perform well e.g. not shooting a black person who is disarmed. The exception was when the police officers were sleep deprived. The implication being that that fatigue blocks or degrades the PFC and the inability to block their implicit bias. More on the importance of sleep here.
Couple takeaways here: 1) Implicit bias is just that: implicit. It's not something you can or should feel bad about as it's a deep-seated biological, evolutionary behavior. 2) it CAN be overcome through recognition, training, and habituation. So no excuse for bias behavior.
The Importance of Cognitive Awareness to be a “Good Person”
When it comes to helping people in need, compassion is more important than empathy. Several key issues here: 1) we are less likely to act to help faceless, distant, “them” individuals who are in need. a known single individual who is a relatable “us” — e.g. the neighbor’s kid — is much more likely to draw action from us that starving kids in some far off unknown place in the world. 2) The more vivid and stark our empathetic response — the more likely we are to viscerally feel the pain of others and ironically we actually want to avoid or suppress the pain of ourselves which often leads to escaping the situation and not taking action.
Couple take-away’s here: 1) the need for a detached cognitive approach rather than an emotionally charged one. Are we looking to viscerally feel like others and do nothing or are we looking to be effective and actually help? I think most of us would define compassion by our actions, and hence the need for a cognitive detached approach. 2) we need to habituate compassion — neither a visceral limbic response nor a purely reasoned approach should be relied upon — but like all implicit and automatic behaviors, compassion should be trained and habituated so that we don’t rely on our fragile response systems in those moments that require compassion. Practice makes perfect and training yourself and certainly training children are important in this regard.
To be a “good person”, we need to protect our cognitive resources. Many of our basic behaviors are evolved from our limbic system including the “us” vs. “them” phenomenon that causes us to react to others with fear and anxiety, Our prefrontal cortex and cognitive system are able to overcome those biological reactions and lead us to take a measured or reason decision or action. Numerous studies show that increased cognitive load on the frontal cortex — decisions, stress, and even physical degradations of hunger and tired lead to less prosocial behaviors — e.g. individuals will be less charitable, helpful, and are more likely to lie. Bottomline — to overcome our base biological reactions — we need to be in a “good place” — well fed, well rested, and in a position to allow our cognitive function to work its best. Anyone who has faced an emotionally charged situation on an empty stomach and tired knows this all too well.
This article is part of a series of posts about the brain. The next article in the series is: The Brain Science Behind Behavior.
Feel free to check out the start of the series here which includes links to the other articles on neuroanatomy, behavior, learning, AI, and free will.
