Could Human Evolutionary Changes Be Behind Mental Disorders?

By Charles Choi | August 9, 2018 10:00 am
(Credit: Researcher97/shutterstock)

(Credit: Researcher97/shutterstock)

The same recent evolutionary changes that make humans prone to bad backs and impacted wisdom teeth may also tweak genes in ways that make people vulnerable to schizophrenia, bipolar disorder and other mental disorders, a new study finds.

Scientists have long suspected that common ailments like lower back, knee and foot pain are likely due to the evolution of upright walking in the human family tree. And there may be a connection between the fact that 70 percent of adults develop impacted wisdom teeth and the evolutionary reduction of jaw size in the human lineage and modern changes in diet.

“Similarly, rapid expansion of brain size and cognitive abilities in humans has been key to our evolutionary success,” says study senior author David Kingsley, a developmental geneticist at Stanford University. However, at the same time, bipolar disorder and schizophrenia impact more than 3 percent of the world population. Kingsley reasoned this vulnerability to mental disorders might also stem from recent evolutionary changes controlling human brain size and structure.

To find out, Kingsley and his colleagues focused on DNA regions found in humans but not other animals. “We knew we might be onto something when a particular human-specific sequence was located right at one of the places that has previously been associated with common psychiatric diseases in human populations,” he says.

Hope For Treatment

Specifically, the scientists focused on the gene for a protein called CACNA1C, which helps direct the flow of calcium in and out of cells. Calcium influences the electrical activity of neurons and helps control the release of the neurotransmitters that neurons use to communicate with each other. Previous research has tied CACNA1C to risks for both schizophrenia and bipolar disorder, as well as anxiety, depression, obsessive-compulsive symptoms and autism.

The researchers focused on the so-called “non-coding” parts of this gene – these are the ones that don’t carry instructions for building the CACNA1C protein. When they compared the standard human genome used as a reference guide with the diverse range of human genomes from across the globe collected for the 1,000 Genomes Project, they discovered a significant variation in one particular region of the gene.

The research team’s analysis of the 1,000 Genomes Project’s data suggested that changes in this particular region could be increasing or decreasing the activity of the CACNA1C gene in ways that might influence risk for mental disorders. “Fifteen years after the initial sequencing of the human genome, we are still finding important pieces of the genome that have been missed in previous studies,” Kingsley says.

He adds, “In the future, this may help better match a patient’s particular DNA risk factors with the drugs most likely to be beneficial.”

The scientists detailed their findings online August 9 in the American Journal of Human Genetics.

MORE ABOUT: genetics, mental health
  • Glenn

    Very interesting but much ado about nothing. People make a living investigating this sort of trivia?

    • Frankie

      Seriously? Learning more about some of the most severe and least treatable mental illnesses, like schizophrenia and bipolar disorder, is much ado about nothing? You wouldn’t say that if you knew anyone with schizophrenia or bipolar disorder. In 20 years with this information we may be able to literally fix the genetic mutations that cause these disorders. Scientists, academics, and other intelligent people are fascinated by this. Yes, people make a living learning everything they can about our natural world. Better than swindling people out of their money based on lies about a Bronze Age Middle Eastern deity.

      • Glenn

        Frankie I’m all for scientific research investigating the cause of serious mental illness. But I feel chasing speculations on evolutionary change is not a productive line of inquiry. I’ve long given up on discovering the gene that causes schizophrenia. The biological discoveries have not been very helpful either. We can say that their is a statistical likelihood that someone with schizophrenia has larger lateral ventricals than someone who doesn’t have schizophrenia. The most important finding for schizophrenia occurred about 50 years ago when someone observed an improvement in psychotic symptoms when a person with schizophrenia took Thorazine. We haven’t really made much progress beyond that. Why not? We certainly have poured quite a bit of research money into investigating the cause and treatment of severe mental disorders with not much to show for it. I certainly hope we can do better. I am skeptical that investigating human evolutionary changes is the key.

        • Per-Einar Dahlen

          There are many ways to find solutions. Finding the root cause (e.g. altered genes), might help us go straigth to the solution, instead of some “band-aid”, for the effects of the disease.

          • Glenn

            Sounds like you are a determinist and not a dualist. Fine. But what about Mother Nature? What is the survival value or reproductive fitness advantage to mental illness? Isn’t it difficult to explain mental illness by natural selection?

          • sll1965

            That is an interesting idea. Here’s another one. Behaviors that are now addressed as mental health issues and detriments may actually have been beneficial tens or hundreds of thousands of years ago.

          • Glenn

            You are right. Us humans are always in a hurry. Mother Nature is not in a hurry.

          • Per-Einar Dahlen

            Natural selection is not fool proof, especially when in a more modern day social homonid group. Besides, some mental illnesses dont really show until adulthood, and the you get the chance to reproduce before the onset.

          • Glenn

            Huntington’s chorea is the classic. But now we can see if we are carrying the gene and that knowledge might influence reproductive decisions. What concerns me is checking chromosomes before birth. If you find out you are carrying an unborn child with an extra 21 chromosome would that warrant a decision to terminate?

  • RPJ

    As a society we have created an economy that is literally toxic to us and the planet, we walk around in clothes and believe our natural form pornographic, the vast majority of adults believe in magical beings that turn water into wine and ride horses into a special dimension; almost every moment of our lives are so separated from any objective review of reality that calling small variances from this collective insanity mental illness is yet another addition.

    I think that if you are not depressed or anxious considering how foreign our lifestyle is to our evolved behavior and the threat this behavior is to yourself and others – you carry the genetic abnormality that is dooming the species and the earth.


Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!


See More

Collapse bottom bar