The science of hugging, and why we’re missing it so much during the pandemic
“What I miss,” said one colleague last spring, during one of our weekly online team meetings, “are hugs, great big man-hugs, like I share with my dad and close male friends.” The sense of touch has long been a shared fascination for our research group of neuroscientists and experimental psychologists. During the pandemic, everyone else has started to talk about touch too – and the negative impact of its loss.
Twelve months later, hugs are still at the forefront of many people’s minds. One recent survey put hugs fourth on a list of 30 things people are most looking forward to after lockdown, just behind visiting friends and relatives (who they will no doubt be hugging) and eating out in restaurants. Refraining from touching or hugging our friends and family has proved really difficult over the last year, and the sight and sound of a loved one over Zoom rarely feels enough. To understand why we crave hugs and the touch of other humans, we need to look to our evolutionary and social history – and our skin.
Humans are born helpless; from birth we are reliant on others to feed us, keep us warm and comfort us when we are distressed. Like all mammals, we are innately predisposed to seek physical contact to ensure our own survival. Touch plays a major role in early nurturing interactions. Skin-toskin contact between a mother and her infant helps regulate the infant’s heart and breathing rate, reduces levels of stress hormones, promotes growth and shapes the developing brain.
The more reliable and sensitive this early care-giving is, the stronger the benefit will be to a child’s health and wellbeing later in life. Touch sends a signal to babies that support is available and they are safe. As we grow older, touch plays an important role in the formation and maintenance of adult social relationships. When distressed, we revert to our earlier experiences of touch, relying on non-verbal support such as handholding, hugs and caresses.
The comforting, rewarding benefits of touch are rooted in our skin, which is innervated with a variety of sensory receptors that inform us about what is happening on the surface of our body. A fly lands on our nose, we get an itch; we stub a toe, we feel the warmth from the sun, someone squeezes our hand. These signals are combined in our brains alongside contextual information, such as how we feel
and who we are hugging, to generate the rewarding, pleasurable sensations that many of us currently crave.
Until relatively recently, neurobiologists studying our sense of touch have focused on the sensory nerves that allow us to detect and explore surfaces, textures and objects. These sensory receptors, found most densely in the skin of our hands and fingers, rapidly send signals to regions of the brain that process this aspect of touch. But researchers are now becoming increasingly interested in a subset of touch-sensitive nerves in core regions of the body, such as the back, which have only recently been discovered.
This second type of sensory nerves send signals to areas of our brains that deal with emotional processing. They are most responsive to skin temperature and gentle, stroking touch. Observational studies find that when people are asked to caress their infant, or their romantic partner, they spontaneously use the slowstroking speeds that these nerve fibres prefer. This touch is subjectively perceived as pleasant; it calms and soothes us physiologically, reducing heart rate and buffering against the effects of stress.
When stimulated, these nerves send signals via the spinal cord to the brain where they release a cascade of neurochemicals. One of the most notable chemicals among these is oxytocin, a hormone released by low-intensity skin stimulation such as hugs. Oxytocin is known to play important roles in social bonding, and can reduce stress and increase our tolerance to pain.
The release of oxytocin during social interactions is context-dependent: only when a hug is wanted will the comforting and rewarding effects be felt. When touch is desired, the benefits are shared by both partners in the exchange. Notably, these partners don’t have to be human. Oxytocin levels increase in both a dog and their owner when the animal is stroked and petted, perhaps in part explaining why, when so many of us have been starved of touch during lockdown, the number of people owning pets has risen.
Over the past year, Covid restrictions have had a significant negative impact on many people’s wellbeing, causing loneliness and distress. At the same time, we have had to inhibit our natural instincts, programmed over millions of years of evolution, to use touch to calm, soothe and show we care. Released from lockdown restrictions, we’ll rapidly start displaying the behaviours that we’re predisposed to share. Though perhaps we will now appreciate them a little bit more.
Dr Susannah Walker is a reader in behavioural neuroscience at Liverpool John Moores University