Philosophy of Genetics

Nature vs. nurture

Our nature (genes, innate qualities) is affected by our nurture (parents, friends, environment, experiences).  Yet, as I have argued, differences are nearly always due to nature (not nurture or free will):

• Motivation, personality, crime, ambition and leadership skills are all in our nature, not nurture.
• Men and women are innately different from each other
• Poverty and social status can be explained by nature, leading to an unequal distribution of wealth and resources
• No two people have the same nature, due to their gene variants.  Even identical twins can be different from each other because the genes of one may switch off under various (expected) scenarios
• The only way nurture can affect us is if our nature is designed to be affected by that nurture. (Our natural development expects certain nurture for tuning purposes, or for selecting different innate responses to a situation)
• Humans are made of a special form of matter, that brings millions of years of experience from the past to the present (that is why we can have an innate disposition toward our current experiences)

People shouldn't have to accept the way they are born (especially if they are born followers, or born psychotic!). Still, we can't change our nature with drugs, and we probably can't change our genes much once we're developed.  So genetic selection of our children before birth (based on individual choice, without government involvement in eugenics) will become the debate of the future, to create fairness and justice.  Parental nurturing doesn't seem to have any long term effect, without genetic changes as well.

Let's not leave the question to politicians.  Not everyone is cut out to be the President.  Not everyone desires free speech. It's the lack of desire and motivation that is truly unfair.

The Druggable Genome; or, the limit of what drugs can do

I previously discussed human development from conception to adulthood, because it’s relevant to a fundamental question – What can we change about ourselves after we're born (using drugs, or by altering our genes, etc)?

Through the process of development, we're born with two arms and two legs, and it seems nearly impossible to add another arm or leg (with drugs, or otherwise), since the differentiation of cells takes place in irreversible stages, and quite early in the process.  Those development genes are programmed to work in the context of an undeveloped body, not a fully developed one.

Still, some things can be changed after we're fully developed.  Some psychological outcomes (like depression) can be treated by drugs.  But it’s not clear that the underlying cause is treatable.  If you get depressed easily if someone dies, that tendency is deeply embedded in the developed circuitry of your brain.  Other people are less depressed in the same situation, due to their gene variants, which program their brains to be less sensitive to traumatic events.

There is some hope that stem cells could be introduced into an adult body, and re-generate cells (nerves, skin, etc).  Skin can repair itself when cut, because we all have stem cells in our skin.  So some development is possible, even after we've reached adulthood.  But unless that new development is guided differently from before (by different genes), it won’t make you a different person.

Drugs can affect us, but only to the degree that the form of the body has developed itself to be affected.  Recent debates have focused on how many targets (usually proteins expressed by genes) in the human body are druggable.  Possibly 3,000 to 5,000 targets are druggable, which is only a tiny percentage of the whole. 

Any change to our genes would require a change to the genes in each of our 100,000,000,000,000 body cells, which is certainly possible, through the introduction of HIV-like viruses, which can embed new genes inside many of our rapidly dividing cells.  But even new genes can't reverse all the previous steps of development and re-generate our brains from scratch. 

So our personality probably can't be affected by either drugs or gene treatments.  Certainly, we know of targets in the brain that allow us to mitigate conditions like depression, and we have antidepressant drugs for that.  But do targets exist to improve charisma, ambition, or desire for leadership?  I doubt it.  Does the development of the brain leave itself open, such that we may alter our basic personality with drugs?  I don't think so.  So the only time we can dramatically change things (personality, etc) is at the time of conception.

Development genes and stem cells

Human development is breathtaking in its complexity.  After an egg is fertilized by a sperm, the cell starts to divide.  Some of the earliest cells in the clump are known as embryonic stem cells because they can duplicate themselves endlessly, and change themselves (or differentiate) into any cell in the body by selectively switching off some of their genes.

Later, the cells become more specialized.  The neural stem cells can only differentiate into neural cells of various kinds, and skin stem cells can only differentiate into skin cells (but not neural cells), even though the underlying genes in each cell are still the same (but selectively de-activated).

As development continues, three layers of cells (germ layers) form – the “ectoderm”, “mesoderm” and “endoderm”.  The mesoderm cells further develop into the muscles and blood, the endoderm develops into the digestive tract and lungs, and the ectoderm develops into the skin, nerves and brain.

It's all an iterative process of increasing cell specialization.  As our hands develop, for example, they begin as tiny buds of mostly undifferentiated cells, like the hands of gingerbread men.  Initially, our fingers are webbed like frog feet, but eventually the webbing cells are killed when they receive the programmed cell death signal, for which they are designed to respond.

I’m always most interested in the development of the brain itself, a process known as neurulation.  The neural cells continue to differentiate into specialized neurons in the brain.  A sort of chemical grid, or map, guides them as they migrate to their proper position, connecting with other neurons along the way.

There are two types of development in the early brain.  Activity-independent mechanisms (such as differentiation, migration and axon guidance) proceed according to genetic programming, independent of the environment (neural activity and sensory experience).

But once the neurons are in place, with their axons connected to other neurons, activity-dependent mechanisms of development (influenced by the environment) can begin.  Neurons do not connect directly with each other.  Instead, there is a gap, called a synapse, between every neuron, where chemical signals pass back and forth.  The chemical signals are vulnerable to being intercepted by drugs, like antidepressants and antipsychotics, because the brain is designed for exploitation by "global signals" and external agents (if not, the neurons would connect together directly).

The synaptic connections between neurons change over time, influenced by our experiences. But those are not just any experiences.  They are the specific experiences for which our development was programmed to respond, like an elevator which is programmed to respond to "button presses" but not loud screams.  Some genes are programmed to switch off (semi-permanently) in some people under certain environments, which is why identical twins (people with the same genes) may differ.  One twin may have a slightly different experience in his life, for which a particular gene is programmed to switch off, so now the twins have, in effect, different (active) genes!

We learn skills, perfect them, and make new memories – all of which are possible by the activity of the brain.  The genetically developed substructures in our brain help us remember new things (hippocampus), motivate us (amygdala), allow us to plan (frontal lobes), and learn language and other skills.  Evolutionary psychologists believe we have evolved hundreds of specialized regions in the brain, each triggering specialized human desires, motivations and behaviors.  Since each of us has different gene variants (probably leading to a different amygdala structure), no two people are motivated by the same things.

The Male warrior effect

New research shows that men have an innate set of personality traits that are particularly tuned for responding to invasions and initiating wars.  Specifically, “men respond more strongly to outward threats … cooperate well in the face of adversity … [and] are more likely to lead groups in more autocratic, militaristic ways” than women.

I’m always interested in how a behavior can be innate.  What structures in the brain would the genes have to build to effect the behavior?  I believe there must be at least 3 sets of genes that enable such development, and implement the innate dispositions:

1. Brain structures must first be developed to detect the situation (e.g. invasion), and that detection must be reduced to a simple “symbol” (or "word") in the brain, for easy transmission to other parts of the brain in a standard way.
2. Once the situation has been reduced to an "invasion" symbol, other modules in the brain (previously developed by the genes) can react to the symbol.  In the case of invasions and war, men have innate circuitry that waits until the symbol is received, then orchestrates the "disposition toward the detected situation".
3. The disposition toward the situation is implemented as a set of brain modules.  For example, "autocratic behavior" and "cooperation" are highly complex, probably involving an increase in confidence in one's own ability, etc.

Why must a situation be first reduced to a word or symbol?  Because the "reaction circuitry" in the brain needs to develop independently, yet still have something simple to trigger it.  That trigger must be well known to the genes that build the circuitry.  The reaction circuitry shouldn't have to worry about detecting the "invasion", just responding to the alert.  Also, by reducing the situation to a single symbol, only a few genes are needed to alter how person A (vs person B) will respond to that same scenario, thus explaining human diversity.  There are only a finite set of human genes to build these difference scenarios, so reducing the situation to a symbol makes it easier to create different innate responses to the same situation, in different people, due to their gene variants.

A Theory of Genetic Justice

John Rawls' famous Theory of Justice proposes that the rules of society be designed with a "veil of ignorance" over what our future position in that society may be.  In other words, if we don't know ahead of time our class, intelligence, social status, or "distribution of natural assets and abilities", how would we design our government and society, to give us the best life under every possible scenario under which we could be born; rich or poor, smart or dumb, high or low?

Rawls says that we'd probably design a society in which:

1. Everyone can enjoy basic liberties, and
2. Any inequality of distribution of resources would benefit everyone; opportunities are open to all people with merit, and everyone has a fair chance to develop the skills that would allow them attain merit

So let's consider the genetic perspective, for a moment:

• No two humans have exactly the same gene variants
• Variations in human motivation and talent are largely explained by genetic differences
• We don't have genes; we are our genes

So is Rawls' theory of justice compatible with genetics?  Certainly basic liberties (freedom of speech, ability to run for political office) are nothing without the desire for them. Yet desire and motivation are themselves innate!  Ambition is innate.  Leadership skills and charisma are innate. Not everyone has the fair chance to develop merit, because not everyone is self-motivated.  Some people want to be followers.  Some people are easily derailed by poor impulse control. 

So not everyone "wants" to exercise their basic liberties, because of who they (genetically) are. Yet it's still unfair that some people can afford more free speech than others (because they can buy time on television to promote their favorite cause).

I believe "genetic justice" would require:

• Free (government subsidized) ability to replace your genes with the gene variants that make you motivated to desire basic liberties (if you don't have those variants already)
• Free access to the gene variants that give you the motivation to develop basic skills (merit), since "time on task" leads to skills, but requires motivation to spend the time

Not everyone is innately motivated (without genetic alterations to their nature) to study or improve themselves.  It's just not "who they currently are".  Yet without merit, they will be poor, and will have little access to promote their ideas to a broad audience (free speech).  Of course, no one should be forced to self-alienate themselves by altering their genes (because it does end up changing your nature).

Simply stated, if one does choose to alter his genes, society should pay for it.  And if he refuses, society should support him in the form of monthly Welfare checks, long-term Head Start programs, etc.

DNA and social behavior

There is some evidence that human personality differences may be explained by differences in our so- called "junk DNA" (i.e. the 95% of our DNA that's not used to make protein), according to a study done by researchers at the Yerkes Primate Research Center and the Center for Behavioral Neuroscience.

[The technical term "microsatellite length", used below, refers to how often a subset of the gene repeats itself.  Each unique number of repeats (1, 2, 3... etc) describes a unique "gene variant" (variant 1, variant 2, variant 3, etc).]

"This is the first study to demonstrate a link between, gene expression patterns in the brain and social behavior across several species," said researcher Larry Young. "Because a significant portion of the human genome consists of junk DNA and due to the way microsatellite DNA expands and contracts over time, microsatellites may represent a previously unknown factor in social diversity."

Genes and Personality

A recent article in Psychology Today describes the reaction of George Washington University psychiatrist David Reiss, after reviewing the results from his study on genetics and personality in child development.

"It's a radical revision of contemporary theories of child development," says Reiss. "I can't even describe what a paradigm shift it is."

According to the article, "parents appear to have relatively little effect on how children turn out, once genetic influences are accounted for ... Genetic influences are largely responsible for how "adjusted" kids are: how well they do in school, how they get along with their peers, whether they engage in dangerous or delinquent behavior."