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In 2020, the Human Touch Is Special

In 2020, the Human Touch Is Special

Photo: fauxels/Pexels.

It took researchers working on two continents nearly two decades to discover the neurotransmitter called serotonin. Though scientists thought at first that it was unimportant, they realised with time that it is integral to many human activities. And as serotonin finally came into focus in the 1950s, so also did a new branch of science: neuroscience.

Serotonin is associated with emotional wellbeing and is responsible for many functions. Curiously, 90% of the body’s serotonin is located in the enterochromaffin cells in the gastrointestinal tract, where it regulates intestinal movements. The remaining 10% is secreted by the central nervous system, where it regulates mood, appetite and sleep, and is involved in memory and learning.

The links between serotonin and depression are also well-established, and antidepressant drugs often target serotonin receptors in the body. However, this neurotransmitter is capable of much more, as various studies have found.

In the 1950s, the American psychologist Harry Harlow conducted experiments with monkeys and realised that touch forms emotional bonds in infant monkeys. In the 1970s, a shortage of incubators in Colombia prompted nurses to place the premature babies naked on their mothers’ bodies, and wrapped them with a blanket. The babies did very well, and this method – called ‘kangaroo care‘ – has since been a standard in nursing.

In 2004, researchers found that touch, even through massage therapy, could boost the level of serotonin in the body. In 2016, another study confirmed that the brains of children who were touched more often showed higher capacity for social development. Researchers at the Touch Research Institute at the University of Miami have even found that touch can improve both mental and physical well-being.

In June this year, a care home in Brazil set up plastic ‘hug tunnels‘ where people could hug their elderly parents without increasing each other’s risk of contracting COVID-19. The ageing parents had a joyous experience; a hug, even through a plastic sheet, is better than no hug at all.

Enter locusts

In 2009. Michael Anstey, Swidbert Ott and Stephen Rogers, from the University of Cambridge, monitored serotonin levels in desert locusts. Normally solitary grasshoppers become gregarious under certain conditions and form a large swarm that hunts for food as one – as India recently witnessed flying through the country’s north and destroying crops. When the researchers stimulated the insects’ hind-legs, their serotonin levels shot up 3x and they began to gregariate.

They also demonstrated that serotonin-inhibiting agents could allow locusts to remain calm and solitary even if they were crowded together. On the other hand, injecting serotonin promoters induced swarming even without any other stimulants. In both locusts and humans, serotonin regulates appetite and sleep. But with too much serotonin, locusts swarm and develop a voracious appetite.

In 2018, Yemen and Oman received an unprecedented amount of rainfall, and locusts in the desert began to reproduce in great numbers. Subsequently, they swarmed and flew into Ethiopia and Somalia. In October 2019, East Africa received intense autumnal rains and a late season cyclone. By April, the resulting swarm had moved into Pakistan and destroyed about 40% of all crops. From there, the swarm moved to India and wreaked havoc.


Also read: Climate Change Brings the Worst Locust Attack in Decades to India


All positive forms of touch release serotonin, so as such this neurotransmitter forms part of the biochemistry of what it means to be human. There are specific nerve endings on the backs of social mammals called c-tactile afferents. These nerve fibres are attached to hairs and respond best to slow touch and strokes. When activated, they trigger a cascade of hormones, including serotonin. Locusts also have tiny hairs on their hind legs that behave the same way. In humans, however, physical touch helps relieve pain, lifts the mood and reduces stress.

We need all of these advantages in our present moment, with physical distancing as a central feature of our social lives. Without being able to move around as much as we’d like and interact with our loved ones at will, many of us are likely to be lonely. The COVID-19 pandemic and its influence on society, especially through isolation and stigma, has also triggered parallel epidemics of depression and anxiety.

The underlying virus has been testing so many spheres of human endeavour. It is curiously ironic that human activities have contributed both to the birth of the ravenous swarms and the virus that would have us not hug or hold each other.

Akhila Vijayaraghavan is a Chennai-based environmental consultant, photographer, diver and writer.

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