I’ve been doing a fair bit of crying recently. My younger brother died suddenly, and as a family we have shed many tears at his premature passing. So I thought I would look at the science of crying in this week’s column.
Psychology and neuroscience professor Robert Provine has written in a most accessible way about human behaviours such as crying. The term encompasses sobbing, known as vocal crying and emotional tearing – what might be termed the quiet moments of shedding a tear.
As children, we engage more in demonstrative vocal sobbing, while as adults we tend towards silent weeping.
Crying and laughing
When it comes to physiology, it helps to look at crying and laughing together, Provine says.
“Specialists may argue whether there is a typical cry or laugh, but enough is known about these vocalisations to provide vivid contrasts. A cry is a sustained, voiced utterance, usually of around one second or more (reports vary), the duration of an outward breath. . . Cries repeat at intervals of about one second, roughly the duration of one respiratory cycle . . . A laugh, in contrast, is a chopped (not sustained), usually voiced exhalation, as in ‘ha-ha-ha,’ in which each syllable (‘ha’) lasts about 1/15 second and repeats every 1/5 second.”
But laughing and crying share one unusual feature: perserveration, which is the tendency to sustain a behaviour once it has started.
“These acts don’t have an on-off switch, a trait responsible for some quirks of human behaviour. Whether baby or adult, it’s easier to prevent a bout of crying than to stop it once under way, “Provine says. “ Crying causes more crying. Likewise, laughter causes more laughter, a reason why headliners at comedy clubs want other performers to warm up the audience, and why you may be immobilised by a laughing fit that can’t be quelled by heroic attempts at self-control. In fact, voluntary control has little to do with starting or stopping most crying or laughing.”
Grief of bereavement
Which is something I to which I can attest when it comes to the sudden grief of bereavement.
But quiet tears are different and so what is their evolutionary purpose? They contain a natural antiseptic agent, lysozyme, which helps lubricate the eye. However, Provine points to evidence of a more fundamental biological role for tears. It seems they contain a substance called nerve growth factor (NGF), the concentration of which increases in tears after the cornea has been damaged; this suggest a healing role for NGF. And the topical application of NGF promotes the healing of corneal ulcers and may increase tear production in dry eyes.
Healing tears
From an evolutionary perspective, Provine notes that “non-emotional, healing tears may have originally signalled trauma to the eyes, eliciting caregiving by tribe members or inhibiting physical aggression by adversaries. This primal signal may have later evolved through ritualisation to become a sign of emotional as well as physical distress.”
In this scenario, the visual and possibly chemical signals of emotional tears may be secondary consequences of tear-gland secretions that originally evolved in the service of eye maintenance and healing. It will be interesting to see where future research into tears and crying leads to.
Reflecting on our recent loss has also prompted thoughts about the social and cultural dimensions of grief. Seeing the familiar faces of friends and family is hugely comforting in the days immediately after sudden death. It is a point borne out by recent research from the University of Haifa’s International Centre for the Study of Loss, Bereavement and Human Resilience, which found the way society relates to people who have suffered a loss is critical to the way the grieving process is managed, because the social component is very important in coping with bereavement.
And so I’d like to say a sincere thank you to everyone who has rallied around since Fiachra’s passing.