Child Development

Adverse Childhood Experience

The downstream effects of forcible parental separation are all too predictable.

Posted Jun 22, 2018

Nature or Nurture? Neither.

Children are nothing if not resilient. So, how can it all go wrong? Last time I talked about the innate mechanisms that generate caring behavior in normal—and I do mean normal—adults, and what can happen in extreme cases when those mechanisms are damaged or interfered with. Brain damage, and psychopathy. But, what about the cases where the child’s brain has not been damaged beyond repair, but it has still had to respond to adverse conditions? This—the effect of adverse childhood experiences (ACEs)—is a well-studied area in developmental psychology. In addition, it links to what we know from studying other species, as well.

Scientists love this sort of convergence—it’s a good sign that we are on the right track. What happens to calibrate offspring to their environment falls under the umbrella of what we call “life history theory” and it changes everything. Once you understand what life history theory implies, then questions of whether a given trait is explained by “nature or nurture” become not so much wrong as hopelessly naive.

The Longest Journey Begins with a Single Decision as to What Sort of Vehicle to Use

If life is a journey (and, apologies for the cliché) then life history theory tells us what sort of vehicle is best suited to that journey. As you set out on your road-trip what car are you going to rent? To know that, you need to know something about the road you are going to take.

Is it likely to be flat and mostly predictable? Numerous refueling stops, decent repair stations, law-abiding fellow road users? Then you can probably take it easy in that sleek, open-topped sporty number. Enjoy the scenery a bit. That’s the equivalent of a relaxed (slow) life history strategy. Offspring calibrated to this grow and mature slowly, with lots of loving care. They take few risks—they don’t have to.

But what if the road is likely to be rougher, with long stops between re-fueling, maybe even non-tarmacked in places? Then a less sporty, but more practical four-wheel drive may be in order. A somewhat faster life-history requires more risks taken, so you have to grow up faster.

And, if you are predicted to drive totally off-road, in something approaching hostile territory, then you had better get yourself something like a tank. The latter is the equivalent of a fast-life history strategy. No one can be trusted, so you had better go equipped. Armored against interactions with the outside world (which can only damage you anyway) you trundle aggressively through an untrustworthy terrain, ready to blast off at friend or foe. Friend? You recognize few, if any. Of course, from the limited viewpoint within your tank, you are going to miss many opportunities for interaction, and the mutual benefits that could accrue from this.

Here’s the thing: Across taxa—and not just mammals this time—there are switches for selecting which life history strategy you are going to go down, fast or slow. A large part of what we study in biology is the precise mechanisms of these switches in particular species. In some species, the switches make such profound changes that we didn’t even know that we were looking at one species until recently. The classic example of this is Coho salmon, which come in two varieties:  Hooknose and Jack. One is large, brightly colored and aggressive, the other is small, cryptic and sneaky. Genetically, they could be twins. Their fast/slow switches are tied to ecological conditions.

But in humans—and in all mammals—one of the key sets of switches is the type of parental care you receive. This is your first road-map telling you about the likely life-path you are about to go down. Will it be relatively smooth sailing, with mostly trustworthy people who return love with love—mutual co-operation leading to mutual benefit, or will it be a dog-eat-dog world where kindness equates to weakness, and all interactions are zero-sum games like poker? Take it easy, or live fast and die young?

Brains and Genes

We often use rodent models to get a handle on the mechanisms—because we share 92% of their DNA, and the key basic brain structures are the same. Of the roughly 4,000 genes we have studied, fewer than 10 are found in one species but not the other. A key gene here is the GR gene. It grows particular parts of the brain—especially the hypothalamus—associated with appetite, reward, and reward feedback. If Freud’s Id had a location in the brain, it would be here.

Contrary to the popular view of genes as fixed in their action, they turn each other on and off in a perpetual dance. That said—a key time for whether genes express themselves or not is in early infancy. The technical details of such epigenetic activities are interesting, but I’m just going to mention one: Methylation. What this amounts to is uncoiling of the gene (“demethylation”) in response to local conditions making it express its full range of action.

You can play with it here at the excellent University of Utah site. (Really—give it a go, it’s fun to watch in action.)

The essence of the story is this—intense parental affection during infancy pushes you down a slow life history path. The offspring's hypothalamus grows as relatively easy to satisfy. The offspring will grow up relaxed and less risk-taking. They live longer. The opposite actions—parental indifference, neglect, or even violence—pushes the offspring down a fast life history path. Early reproduction, risk-taking, early death. And it’s tempting to see these results as issuing from bad parenting—and in a way, it is. But it’s also parenting that prepares the offspring for its likely world.

There is no “one size fits all” strategy in the world. The early bird catches the worm … but the second mouse gets the cheese. Whether it pays the individual to be slow or fast, cautious or bold, depends on circumstance. However, the same cannot be said for the rest of us, who have to deal with the fallout of unwanted, or unloved kids, who have now got bigger, and picked up more scars, habits, and traits that damage themselves, and those around them.

Childhood Doesn’t Stop in Childhood

What we see later as broken adults are, in large measure, those doing the best they could with the calibrations that their early experiences of the world provided them with. Were they being calibrated for a world of trust, or a world of fear? They present as depressed, drug-using, violent, or finding difficulty in loving others. All of those behaviors make sense in a world without love or trust. They are attempts to make up for the deficiencies, or to manipulate others to your will, given that mutual benefit is dead to you. And it’s tough to unlearn such lessons once you get to adulthood. Not impossible—but tough. Like the difference between mother tongue and a second language.

We can predict some of these downstream effects using adverse childhood experience questionnaires. It turns out that your answers to ten simple questions (and controlling for adoptions for example) about your early life experiences is highly predictive of an adulthood that is more likely to be filled with troubles to overcome.

Were you treated with respect, or mocked and denigrated? Were you, or your carer, physically bullied (or worse)? Were you pushed into sex at an inappropriate age? Was your early family life redolent of support, or its opposite? Were you physically neglected? Were the people who were meant to care for you absent—either physically, or through intoxication? In brief: Were you allowed to be a child, or were you raced through childhood without being allowed to absorb lessons of trust and nurture, because you were too busy trying to survive and not be exploited?

This is Everyone’s Problem

Children don’t discriminate. They don’t know (or care) about the whys and wherefores, the politics and the rationalizations. All they have is the reality of the tiny world with which they are presented, and the demands this puts on them. They don’t have any idea why the person they are attached to doesn’t show them love, exploits them, or is suddenly mysteriously absent. All they have is an alarm that goes off in their head screaming “This world cannot be trusted—you had better respond accordingly.”

You can see where this is going, can’t you?

If you want a world of adults who are less twitchy, and more trusting, less likely to get involved with drugs, gangs, and violence, less likely to get pregnant early, and less likely to send these burdens down through the generations, then the course is pretty clear. All the standard tabloid (and these days social media) evils are typical fast life history outcomes. The ones predicted by insecure attachment styles in infanthood and childhood.

So, if a more settled predictable grown-up world is what you want, perhaps not taking babies and children away from their caregivers might be a sensible strategy?

Someone recently (and angrily) told me, "It’s all political." Well, if so, then it's high time that politics learned something about growing up.


Stearns, S. C. (1976). Life history tactics: A review of the ideas. Quarterly Review of Biology, 51, 3-47.

Belsky, J., Steinberg, L., & Draper, P. (1991) Childhood experience, interpersonal development and reproductive strategy: An evolutionary theory of socialisation. Child Development, 62, 647-670.

Gross, M. R. (1985). Disruptive selection for alternative life histories in salmon. Nature, 313(5997), 47-48.

Johns, S. (2011) Perceived environmental risk as a predictor of teenage motherhood in a British population . Health and Place.

Nettle, D., Coal, D., & Dickins, T. (2011) Early life conditions and age of first pregnancy in British women, Porc. B. 1721-1727.

Wilson, M., & Daly, M. (1997). Life expectancy, economic inequality, homicide, and reproductive timing in Chicago neighbourhoods. BMJ: British Medical Journal, 314(7089), 1271.


It has just been said that unaccompanied toddlers are appearing in court to answer the criminal charges against them. We don't even have an ACE category for that one. Apparently this is not an Onion spoof.