Humans are symphonies, not salad dressing

A brief meditation the misleading mental model of "nature versus nurture"

Why did use of this word peak in 1940? I have no idea.

What makes us who we are?

When people ponder the role of nature versus nurture in shaping human experience, I think many if not most implicitly invoke a mental model of humans as, well, salad dressing. It goes something like this: There is some percentage of us that is established by our genetic code – call this the oil. There is also some percentage that results from our environment – call this the vinegar. Our experience of living in the world “shakes up” our salad dressing and entangles the two ingredients, but just as we can watch oil and vinegar separate if we let the bottle sit, so too can we use the tools of science to parse out the unique influence that genes and the environment each contribute to who we become.

Note that under this mental model, we have wide latitude in attributing the relative proportions of oil and vinegar in our constituent salad dressing. So, for example, if you are a squishy lib, you might be inclined to believe that most of who we are results from our life circumstances, so you might want to believe that we’re only 15% genetic oil, and 85% environmental vinegar. Conversely, if you’re, say, a “heterodox” commentator who fancies himself committed to following the science regardless of the uncomfortable places it may lead, you might contend the proportions are the reverse. Most people probably fall somewhere in between.

Does any of this ring true? Does this perhaps describe how you think about nature versus nurture? It definitely describes how I used to conceive of things.

But this is the wrong mental model.

To see why, I’m going to offer an alternative: Symphonies. A symphony is produced by an orchestra comprised of musicians playing instruments. If we listen to one together and I then ask you, “how much of this symphony was caused by the woodwinds versus the brass section?”, you’d be puzzled – it’s a weird question. Similarly, if I ask, “how much of the symphony was caused by the skills of the musicians versus the quality of the instruments?”, you’d have no way of meaningfully responding. These are questions with no good answers. We recognize that trying to understand the sound of a symphony by breaking it apart into various subcomponents loses something essential about the entire enterprise.

Now imagine humans as symphonies. Our songs are played by an orchestra made up of millions of tiny “g-nomes,” or gnomes if you will. These gnomes are bestowed to us, we have no control over them – they result from nature. The instruments they “play,” however, are not – these vary depending upon the life circumstances that we experience. Call this the environment, call it nurture, call it “the world,” every orchestra consists of gnomes playing slightly different instruments, and thus every human sounds their own unique symphony.

Now let’s bring in some science. There is no disputing that, if certain specific gnomes are altered in our personal orchestra, our sound will be affected – sometimes dramatically so. For example, there is a gnome called HTT, and if your orchestra has more of these gnomes than is typical, you will develop Huntington’s disease, an affliction that degrades motor coordination and negatively impacts many mental capabilities. So gnomes matter, and in specific instances we can say with scientific confidence, “these gnomes caused this change to our symphonic sound.” No one can reasonably argue otherwise.

This fact, however, does not mean that every and all aspects of how our symphony sounds can be said to be “caused” by particular gnomes. If we were to remove the entire percussion section from an orchestra, obviously the resulting music would sound very different from before. But we’d still be unable to answer the question, “what percentage of the sound of this symphony was previously caused by the percussion-playing gnomes?” It remains a weird and not particularly helpful way of looking at things.

To illustrate this further, consider the following: Let’s say we decide that certain human symphonies sound better if they contain more of a certain tone, including one we might call “intelligence.” Having decided this, can science help us figure out the specific causal role that specific gnomes are playing in creating this tone? Answering that question poses some non-trivial challenges. For one, we’re gonna have to find some way to isolate this tone from the rest of the sounds of our symphony – not easy to do. For another, we’re going to have to agree upon some way to measure this tone – also difficult.

But even if we agree on some method for measuring the “intelligence tone,” there’s nothing about the gnomes that’s driving the process. It’s entirely the product of human decisions about how to classify things – the application of statistics to something we’ve decided we care about and want to “hear more of.” Intelligence as defining a set of various cognitive abilities is the result of social deliberation and empirical testing, it’s not the product of some quality we’ve isolated using natural science. There’s nothing “in the gnomes” that defines intelligence in some way that’s separable from the instruments they play (i.e., the environmental circumstances we experience in our lives).

Why does any of this matter? It matters because seeing humans as symphonies – rather than salad dressing – better helps us appreciate the complex entanglement of “nature and nurture” in making us who we are. In education, it means that when heterodox commentators such as Frederick deBoer argue that “children are shaped predominately by nature, not nurture” or that “educational achievement…passes from parent to child genetically” – we’ll see this not as speaking truth to power but rather as reflecting a fundamental misunderstanding of the science of human behavior.

And most importantly, it means we will recognize that while we can’t do much about the gnomes in our orchestra, we can for damn sure work to provide them with better instruments to play, and thereby work to improve our collective harmony.

Behavioral geneticist Eric Turkheimer kindly took a quick look at a draft of this essay and noted that I’m not the first to invoke the humans-as-symphonies metaphor in the field of behavioral genetics, and subsequent Googling confirms he’s right. So shout out to whoever thought of this first — I’m calling dibs on salad dressing, though. Also, if you want to go deeper on nature versus nurture, I recommend starting with this overview from Turkheimer and then moseying over to his highly accessible Substack.