Nature vs Nurture. Time to end the debate

Since I brought up Darwin in the last post, it seemed obvious I would follow it with one about the nurture vs. nature debate and why it’s misguided and a waste of time.

During this period thinkers like Thomas Hobbes, John Locke, and Marx argued that experience was the prevailing influence shaping behavior. Locke saw the mind as a blank slate to be filled by experience. With the publication of On the Origin, Darwin put forth a systematic explanation for the adaptive variety of life. In his view, it was natural selection that was responsible for the progressive advancements that get passed to the next generation. Interestingly, the two men credited with the theory of evolution, Charles Darwin and Alfred Russel (yes 1 L) Wallace, were on opposite sides of this debate. Darwin was for nature being the main influence:

 “I am inclined to agree with Francis Galton in believing that education and environment produce only a small effect on the mind of anyone, and that most of our qualities are innate.”  Charles Darwin

Wallace thought it was experience:

Leave heredity alone until we have made the environment of every child from conception to death the best possible for its full and free development, and then we can begin to think about the influences of heredity, which may be small.”  Alfred Russel Wallace

One more bit of history.

It was Darwin’s cousin, Francis Galton, who coined the term eugenics and really put the idea into the public consciousness that intelligence was inherited and the result of natural superiority.

That the debate still rages on is absurd. It’s easy to forgive the radical position of those 19thC thinkers; they knew nothing of DNA, GxE interactions or epigenetics. The same can’t be said for those making the argument today.

This debate can become especially vitriolic and extreme whenever people begin discussing pit bulls – particularly if it associated with an attack on a person.

The nature side comes out swinging; claiming that the dog is genetically dangerous ignoring any influence the dog’s experience may have had on its behavior.These people usually come out on the side of BSL because – in this example – all pits are genetically bad.

The nurture side counters the irrationality with irrationality by claiming it is all about how the dog was raised, putting all blame on the owner and ignoring the effects of selective breeding.

Anyone espousing either extremist view, doesn’t know what they are talking about. Surely both sides recognize that the whole argument is based on a false dilemma. The simple fact is that genes can influence behavior. Behavior can influence environment. Environment can influence genes. It’s an interactive and dynamic bouillabaisse with behavior as the ongoing product, but all are affected by each other. And behavior is not the final product because as long as an organism is alive, it has the potential to change.

A fine example showing the absurdity of the whole thing comes from Caspi’s research; it found males (and only males) with a particular variation of the MAOA gene are MOST antisocial IF maltreated in childhood, but were the LEAST antisocial IF they were not mistreated. Here we have the same gene associated with polar opposite effects depending on the individual’s experience. So which is it? Nature? Nurture?

What about if your grandfather’s environment results in heritable epigenetic changes? Does that count as gene or environment? A recent paper in PNAS reports that a single exposure to the fungicide vinclozolin can affect the behavior, gene expression, metabolic activity and physiology three generations later. Once again, the whole G/E debates become rather muddled.

Conover and Schultz expressed the variation in a population like this:

  VP = VG + VE + VGxE + 2Cov(G,E)

Everything is at play, the variation in genetics, environment and the interplay between those two (GxE). Nature/environment doesn’t act in a vacuüm nor is gene expression/regulation a fixed variable, these are interacting and dynamic ventures.

There is no Behavioral Theory of Everything and no one variable that can explain the wide spectrum of behavior. It’s not ‘genetics’ and it’s not ‘upbringing’.

Biology is complex, far too complex to be explained by such simplistic, monolithic and immutable positions; it is a self-serving argument that ignores the individual and hinders understanding.

It’s time to let the nature-nurture debate die. We can do better, and only we do better will we be able to get a deeper appreciation and understanding of animal behavior.

REFERENCES

Caspi A, McClay J, Moffitt TE, Mill J, Martin J, Craig IW et al. Role of genotype in the cycle of violence in maltreated children. Science 2002; 297: 851–854.

Crews D, Gillette R, Scarpino SV, Manikkam M, Savenkova MI, and Skinner MK. Epigenetic transgenerational inheritance of altered stress response. PNAS 2012 : 1118514109v1-201118514.  www.pnas.org/cgi/doi/10.1073/pnas.1118514109

Conover DO, Schultz ET. Phenotypic similarity and the evolutionary significance of countergradient variation. Trends in Ecology and Evolution Volume 10, Issue 6, June 1995, Pages 248–252

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3 thoughts on “Nature vs Nurture. Time to end the debate

  1. What a great discussion. I remember in college touching on this in psychology and biology classes, but you are right that many side with one camp or the other. As I was reading, I was thinking just what you said at the end of the post that it is very complex. Too complex to pigeon hole into one theory or another, especially assigning a mathematical equation to generate a definitive answer. I like your reference to the Behavioral Theory of Everything. Would that not put sociologists and psychiatrists out of business fast. One stop shopping.

  2. Pingback: Nature and nurture in dog raising | Doggerel

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