How much control do we really have over how we think and act?

Our decisions can be influenced by a complex matrix of forces, from parasites to genetics. Carl Dixon explores how much control we really have over how we think and act.

It is a central tenet of western culture that free will exists, that humans are capable of rational, logical thought, able to weigh up decisions and make the best choice. We will accept some deviations — whom a person falls in love with for example is often inexplicable and addiction obviously distorts free will — but these are considered deviations from the norms of adult, responsible behaviour. It is an attractive concept but does it hold up to scrutiny?

If humans have free will then we have a peculiar way of showing it. We spend our adult lives working at jobs we often find extremely distasteful and which make us miserable. We waste our hard earned money on objects that we don’t need or on transient experiences and this over-consumption now threatens the environment that sustains our very existence. Half of the planet is obese whilst the other half starves. Viewed dispassionately, the way humans behave is utterly bizarre. Does it not seem probable, if we truly had free will, that a greater proportion of us would choose to do something else with our lives?

Increasingly we are learning that human decisions are influenced by a complex matrix of external and internal forces and that conscious control over how we feel and act may be illusionary. We are governed by a complex mix of evolutionary drives, childhood nurture, cultural forces, genetics, hormones and biological factors which makes it difficult to tease out cause and effect. We aren’t even sure to what degree our conscious mind is under the control of our subconscious.

A study in the 1980s showed that the brain may commence a particular action long before the owner of said brain is actually aware that he decided to do it. A recent study in Yale suggested, that for rapid decisions at least, the subconscious makes the decision and then tricks the conscious brain into believing that it was actually its own choice. Maybe this also applies to other decision, big and small, that we make in our daily lives.

Humans are part of a wider ecosystem. We may have moved out of the natural habitats that sustained us as hunter-gatherers but the evolutionary forces that shaped our behaviour can’t be shut off at our command. We are the products of long-term processes. Ultimately we didn’t control or direct the trajectory of human consciousness, it evolved to meet the challenges of the past. We can’t always predict how our brain will function when it is faced with a world that is now increasingly alien to that in which we evolved.

We are part of an ecosystem, but we are also ecosystems in our own right. We are in fact an ocean liner with a menagerie of approximately 100 trillion gut microorganisms which outnumber our human cells 10 to one. We are, it seems, only partially human.

How much control do we really have over how we think and act?

We now know that there is direct contact between our guts and our brains. In fact, they can be considered intimately intertwined parts of the same system. For example, serotonin, which impacts on mood is manufactured in the gut.

Changes in the important neurotransmitter GABA is thought to impact on anxiety, depression and bowel disorders.

There is now research that indicates that bacteria positively impact on GABA receptors and some bacteria actually produce their own neurotransmitters. Conversely, scientists in Boston have cultured gut bacteria which actively feed on GABA. Obviously, this complex internal community has a variety of symbiotic, parasitic and competitive interactions which interacts with our brain and immune system and about which we know very little.

It has also been shown that exposure to a soil bacterium through gardening or a walk in the woods, may enhance the quality of life by significantly improving mood and sense of wellbeing.

On a cellular level, it may be that this soil bacteria triggers the production of immune cells that help to curb inflammation.

On a practical level it means walking in nature is good for you. In fact, the gut-brain axis may impact on many aspects of human life, including what we eat and how we think and even how we are attracted to other people.

It is also possible that our behaviour is also affected by parasites; a common phenomenon in the natural world. Rabies is an obvious example how a virus hijacks the host’s brain and changes its behaviour.

Toxoplasma gondii is a common protozoan parasite of cats. Mice pick up this infection from cat faeces and the parasite manipulates the mouse’s brain so that it becomes more reckless and is actually attracted rather than repelled by the smell of cats. This makes the misguided rodent more likely to be eaten by a hungry cat and thus the cycle starts again. More than a third of the human population is infected with this parasite.

Although not conclusive, some studies suggest that humans infected with toxoplasmosis may be more susceptible to disproportionate outbursts of aggression such as road rage, are more likely to be involved in motor accidents due to slower reaction time and may suffer more psychological disorders such as schizophrenia. If the parasite reduces fear and induces risk-taking in mice, might it induce something similar in us?

Some researchers have also postulated that this parasite has subtly impacted on the development of human societies. For example only 7% of British people are infected, however for Brazilians, the figure rises to 67% and in some populations, the level of infection reaches 95%. Perhaps this parasite influenced humans societies by exerting subtle influences over large numbers of people?

How much control do we really have over how we think and act?

The is also some evidence to suggest that the parasite affects people with different blood groups differently. It may also impact on men and women differently — due perhaps to interactions with testosterone — with men becoming less risk-averse, but more dogmatic and with women becoming more outgoing and moralistic. Thus any impact on human society isn’t necessarily negative.

Ultimately belief in free will may be a vital cog in how societies operate, whether it actually exists or not may be irrelevant. In experiments, people behave more selfishly if they have been persuaded that free will is largely an illusion. Why behave well if you are not responsible for what you do? How can society justify the punishment of wrongdoing if the miscreant was unable to choose?

Societies need deterrents. The belief that we are masters of our own destiny also makes us less anxious. The predominance of zombies as the preferred fear factor in films may tie into our deep subconscious fears of a loss of conscious control.

In times past we could lay the blame for our erratic behaviour on fate, karma, gods, witches, fairies, eclipses or Lucifer. Knowing that we are influenced by factors outside our control, however subtly, doesn’t give us a devils charter to behave as we wish without guilt or fear of repercussion. But knowing how we make decisions may help us to make better ones, and perhaps we can all be a little bit easier on ourselves. Perfection still lies outside our conscious control, and metaphorically at least, much of our destiny stills lies in the lap of the gods.


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