Schizophrenia—Evolution of Humanness

Is schizophrenia bound to human evolution? Schizophrenia is a neuro-developmental disorder characterised by delusions, hallucinations, and bizarre behaviours. No other animal displays these symptoms. Depression, addiction, anxiety are all found in other animal species, but not schizophrenia. Schizophrenia is not even found in chimpanzees our most recent evolutionary ancestors. It is inheritable, and highly disadvantageous to survival of the affected person. Given this, schizophrenia should be almost non-existent. Yet it continues to affect a massive 1% of the global population. Something is pushing for the persistence of this disorder and its spontaneous manifestation in humans.

Human evolution separated from the chimpanzees 5.5 million years ago when we walked upright and then acquired language abilities. Language ability developed after 'lateralisation', the separation of brain functions into the left (sequential) and right (parallel processing) hemispheres. The peculiar delusions and hallucinations of schizophrenia can be understood as failure of the complex brain mechanism that enables the speaker to distinguish his thoughts from his speech or that of others. This brain mechanism evolved with lateralisation of brain functions. Loss of brain laterality in schizophrenia has been demonstrated.

Comparison of the gene sequences of early humans and their close evolutionary relatives, the Neanderthals have shown that regions of the human genome that underwent positive selection are enriched by association with schizophrenia. This suggests that schizophrenia susceptibility factors may be a "side effect" of human achievements like language and creative thinking. 

Recent evolutionary modifications in brain wiring and connections may have played a role in the development of schizophrenia in humans. Compared to our closest living relative the chimpanzee, brain connections present only in humans show a higher involvement in schizophrenia. Evolutionary changes in the human brain related to supporting more complex brain functions are paralleled with a higher risk for brain dysfunctions that can manifest as schizophrenia.

However, this genetic susceptibility is actually reducing. A study comparing modern-human-specific gene sites with archaic ones has shown that schizophrenia-risk related genes in modern humans are much less than those in Neanderthals and Denisovans (archaic humans). So negative selection of schizophrenia risk-related genes are probably being gradually removed from the modern human genome.

References

1. https://en.wikipedia.org/wiki/Human_evolution
2. Crow TJ. Is schizophrenia the price that Homo sapiens pays for language? Schizophr Res. 1997;28(2-3):127–141. doi:10.1016/s0920-9964(97)00110-2
3. Crow TJ. Schizophrenia as the price that homo sapiens pays for language: a resolution of the central paradox in the origin of the species. Brain Res Brain Res Rev. 2000;31(2-3):118–129. doi:10.1016/s0165-0173(99)00029-6
4. Srinivasan S, Bettella F, Mattingsdal M, et al. Genetic Markers of Human Evolution Are Enriched in Schizophrenia. Biol Psychiatry. 2016;80(4):284–292. doi:10.1016/j.biopsych.2015.10.009
5. van den Heuvel MP, Scholtens LH, de Lange SC, et al. Evolutionary modifications in human brain connectivity associated with schizophrenia. Brain. 2019;142(12):3991–4002. doi:10.1093/brain/awz330
6. Liu C, Everall I, Pantelis C, Bousman C. Interrogating the Evolutionary Paradox of Schizophrenia: A Novel Framework and Evidence Supporting Recent Negative Selection of Schizophrenia Risk Alleles. Front Genet. 2019;10:389. Published 2019 Apr 30. doi:10.3389/fgene.2019.00389

Creativity

How do we define creativity?

Creativity is the ability of individuals to develop novel and useful products. Novelty, originality, innovation, ingenuity are some of the words often used to define creativity. But originality is just one component of creativity. There is another essential aspect of creativity – the idea should be effective, useful or productive. 

Creativity exists in many domains and is not just limited to the arts, as most people seem to think. Creativity is at work behind most scientific inventions, innovative gadgets, health technologies and economic theories which have changed the world.

Individuals differ in their propensity and capacity to be creative. Many of us are creative in small ways - in ways we find solutions to problems of everyday life. Only a few are highly creative and leave their mark on the world.

What does it take to be creative?

Creative individuals tend to possess some qualities or traits that may contribute to or are associated with their original thinking:

• Excellence: creative people are usually masters in their particular domains.
• Interests: they tend to be interested and curious about many things outside their main subject. This probably enables them to combine ideas or techniques from other disciplines in unusual ways to come up with novel, workable solutions to problems.
• Exploratory: They tend to be open to new experiences, ideas and ways of doing things.
• Motivation: most creative individuals are passionate about their interests and internally motivated.

Creativity is not about sitting and waiting for a sudden flash of insight or inspiration. This insight usually comes after much time spent in gaining knowledge and working hard at the task on hand. Discipline and perseverance are an essential part of the creative process.

As Edison famously said

Genius is 1% inspiration and 99% perspiration

High intelligence does not equate with creativity, however, creative people tend to have an above average IQ.

Can creativity be taught?

The generally accepted view is that creativity is not a set of skills which can be taught or learnt. However, certain habits, tools or strategies can be taught, and an environment that encourages and fosters creativity can be provided in our homes, schools and workplaces.

• Building basic skills and domain-specific knowledge
• Stimulating and rewarding curiosity and exploration
• Encouraging internal motivation, mastery and self-competition
• Providing opportunities and resources
• Promoting a willingness to take risks

Creativity and mental health

Those in creative, artistic professions tend to have a higher than average correlation with mental illnesses including schizophrenia, bipolar illness, substance abuse and suicide risk. 

Conversely, creative activities such as music, dance, art, journaling and poetry writing have been known to promote psychological well-being.

Does treatment of mental illness reduce creativity?

Treatment of mental illness could both help or hurt creativity. When treatment reduces fearfulness and avoidance it helps creativity. When it reduces motivation and flexibility it can hurt creativity. In practice there is usually a delicate balance that needs to be monitored. Some treatments are more effective at preserving creativity than others. Treatment that preserves goal-driven motivation helps all people, not only those in the arts field. As with most other aspect of health, physical exercise and adequate sleep help creativity.

Creativity is not all good nor all beneficial to society. A quick survey of the daily newspaper is enough to demonstrate how people resort to extremely creative ways to cheat, defraud or harm others.

References

1. Flaherty AW. Brain illness and creativity: mechanisms and treatment risks. Can J Psychiatry. 2011;56(3):132–143. doi:10.1177/070674371105600303
2. MacCabe JH, Sariaslan A, Almqvist C, Lichtenstein P, Larsson H, Kyaga S. Artistic creativity and risk for schizophrenia, bipolar disorder and unipolar depression: a Swedish population-based case-control study and sib-pair analysis. Br J Psychiatry. 2018;212(6):370–376. doi:10.1192/bjp.2018.23