For the most part of the past century, humans had increasingly better lives in terms of material well-being, medical treatment and education. And yet, there is a paradox as mental health problems have tended to increase rather than decrease. What’s more, psychiatry and psychotherapy are a mess: diagnoses often diverge widely and treatments are often hit-and-miss.
Randolph Nesse recounts the frustration of one of his patients who had gotten four different diagnoses by four different experts in Good Reasons for Bad Feelings (2019):
When I told her that several kinds of treatment could be safe and effective and that an excellent cognitive behavior therapist near her home would likely be able to help, she relaxed and said, “Maybe this trip will be worth it.” However, later, as she stepped out of the office, she stared at me and shared a parting comment that still rings in my ears: “Your whole field is confused. You know that, right?”
In fact, mental health is most often defined in symptoms rather than causes. That would be unthinkable for modern medicine, comparable to COVID being defined as fever with breathing problems. Doctors know that they want to cure the illness, not make symptoms disappear. And yet, this is exactly what is common practice in mental health problems. However, merely lowering a high temperature does not treat the root cause of an illness. Merely treating depression with SSRIs does not treat the real problem.
People often end up with a whole range of diagnoses. Neurodiverse people, in particular, are prone to suffer from many comorbidities like social anxiety, eating disorders, depression and suicidal ideation. In fact, most mental health problems show a combination of the following symptoms:
- Anxiety
- Depression
- Sleep problems
- Eating disorders
- Addictive behaviour and substance use
Nesse and others have been trying to make more sense of mental health problems using the methods of evolutionary psychology. This is certainly the right path to go, but there is a lot of work ahead. So far we understand very little about mental health and adaptations. Most mental health problems can’t be seen as straightforward adaptations. Here are some examples:
Bipolar disorder: It is well known that people with bipolar are often highly creative, particularly during their hypomanic phase. Some famous people with bipolar: Kurt Cobain, Winston Churchill, Russel Brand and Nina Simone. If you examine the lives of highly creative people, you will find that they leave fewer offspring than the average population. This is particularly true for many highly creative writers and musicians who often die at a quite young age (cf. 27 Club).
Autism (not a mental health disorder but often accompanied by a host of mental health problems): autism has been said to be a recent adaptation to tackle our increasing technological problems. However, no recent mutations for autism can be found, all involved genes seem to be ancient mutations. What is more, even if it’s true that relatives of people with ASD are often engineers and scientists, people with ASD themselves often do not make any major discoveries or inventions. The most compelling argument against ASD as a recent adaptation for me is that it is unfortunately really hard for people on the spectrum to find a partner and maintain a happy relationship. For evolution to take place genes involving ASD would have to spread more quickly, not more slowly.
Schizophrenia: it has been argued that higher sociosexuality that often accompanies psychotic disorders may be adaptive due to a higher chance of pregnancy. This is a very short-sighted view: human offspring need a lot of care over a long period of time, which a (single) schizophreniac parent is unlikely to be able to provide. So, even with higher rates of pregnancy schizophrenia would lead to lower rates of viable offspring.
An interesting finding of Evolutionary Psychology is, however, that a lot of reactions are adaptations and that those adaptations are calibrated differently in different people. Nesse calls this the “smoke detector principle”. Anxiety, for example, was highly adaptive in our evolutionary past. However, like a smoke detector it may be triggered too quickly or too slowly. Different environments in our evolutionary past set different default values.
Mental health problems are highly heritable, ranging from 0.30 for major depression to .80 for ADHD. Another mystery we get here is that there is assortative mating for mental health problems. This is not based on conscious decisions, however. Even if only one partner has mental health issues the likelihood that some mental health issues run in the other partner's family is very high. The same kind of assortative mating can be found in neurodiverse people, with one partner having ASD and the other one ADHD, for example.
Mental health very rarely involves monogenic causes, there are often dozens of genes involved. Genes that are frequently found to play a role often revolve around neurotransmitters and hormones: serotonin, domain and oxytocin. So, we can be quite certain that the genes involved were at least adaptive in the past, even if they may be maladaptive in the present.
In this account, I want to turn the continental view of inherited mental disease on its head and look at inherited environments rather than inherited “bad genes”. The idea of an inherited environment may seem ridiculous at first glance, after all we all inherit the same environment. The famous Roseto effect makes it clear that it isn’t so. Roseto is a town in Pennsylvania that was founded by Italian immigrants. The local doctor made an extraordinary discovery: despite unhealthy lifestyle choices and conditions (smoking, alcohol, men working in quarries) Roseto had no deaths from heart attacks. What prevented the incidence of cardiovascular conditions was most likely the inherited social system and living in a tight-knit community. With each subsequent generation, however, people in Roseto adapted to the more competitive American way of life and finally, there was no significant difference in heart disease in Roseto compared to the surrounding American towns.
When it comes to mental health the same is very likely true. Children now inherit a very different environment from the one their parents and grandparents grow up in. Social ties are much looser and family support structures much weaker, single parent and only child families are common.
Finally, we also know from developmental psychology that some people are genetically and environmentally more susceptible to mental health problems than others who are more resilient. So, who are the people who are higher at risk for mental health problems?
- Neurodiverse people
- Highly reactive babies (Jerome Kagan)
- Children with insecure attachment of the type “confused”
- Children with shy/inhibited temperaments
- Highly sensitive people (see Elaine Aaron)
- Highly intelligent people (see Ruth Karpinski’s hyper-brain hyper body hypothesis)
- Hunter-gatherers (foragers)
Now, the last group may come as a surprise, as hunter-gatherers traditionally had the lowest rates of mental health problems. However, hunter-gatherers who are forced to integrate into our society show the highest rates of mental health problems. Native Americans, for example, experience serious psychological distress 1.5 times more than the general population. They also experience PTSD more than twice as often as the general population and depression, substance use and suicide are very common.
Last, but not least, we know that personality traits are associated with mental health problems: neuroticism predicts mental health problems such as anxiety and mood disorders and openness to experience is correlated with psychosis and introverts are at a higher risk for mental health problems than extroverts in general. Interestingly, the Big 5 inventory is not a human universal and openness to experience and neuroticism are the first two personality factors that disappear when it comes to traditional societies.
To sum up, here are some of the most important mysteries and paradoxes of mental health issues:
- Increasing mental health problems despite increasing material well-being
- Adaptations in the past - maladaptive in the present
- The difficulties of clear-cut diagnosis
- Assortative mating for mental health problems
- Differential influence of personality traits
Evolutionary psychology may help understand these mysteries better. Our ancestors practised different types of subsistence: hunting, gathering, farming and herding. If we see people as evolutionary forager, herder and farmer types, we will be more likely to understand the causes of mental health problems as each type is likely to have different evolved preferences and “instincts”. Our world is very much a farmer world, with 9-5 routine jobs and 40-hour work-week, material values and status orientation, all things absent in a forager world. Hunter-gatherer types, just like real hunter-gatherers, are therefore the ones who are most likely to suffer from mental health problems, followed by herder types.
I have described the above risk group (neurodiverse, HSPs, etc.) as “hunter-gatherer neurotribe”. Not all people who suffer from mental health problems are hunter-gatherer types, of course. Nor is being a hunter-gatherer type an exclusively psychological phenomenon and includes susceptibility to physical conditions such as gastrointestinal problems and allergies as well. Looking at the neurodiversity community one gets a good impression of how wide-ranging the phenomenon is. It also includes transgender, which is about three to six times higher among neurodiverse people than the general population as well as a somewhat more intense attachment to animals (especially among neurodiverse girls).
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