Some people may be genetically prone to be lonely, a study suggests.
Being socially isolated leads to an early grave and is considered to be as damaging as smoking 15 cigarettes a day.
And new research on rhesus macaques – who congregate in groups of up to 200 – revealed some monkeys choose to be lonely for most of their lives.
A team of international scientists believe this suggests their isolation is caused by a persistent trait or traits that they are unable to control.
Researchers from the universities of Exeter, Puerto Rico and Pennsylvania claimed the cause is a mixture of their genes.
Being socially isolated leads to an early grave and is considered to be as damaging as smoking 15 cigarettes a day
Other factors such as age, sex and family size could play a part, claimed Dr Lauren Brent, of Exeter’s psychology department.
She said: ‘Understanding social isolation is really important, and studying macaques might give us clues about human behaviour.
‘Isolation is the latest epidemic among humans, and research has suggested it is as bad for us as smoking 15 cigarettes a day.
‘Given the benefits of social integration, we need to understand why some individual animals tend to be socially isolated.’
How was the study carried out?
The study measured integration by observing how much time the macaques spent grooming others and being groomed – a key social behaviour for the species.
Researchers used data from 429 adult rhesus macaques to make the conclusion, which was published in the journal Scientific Reports.
Factors that led to isolation were age, sex, social status, group size and how long a macaque had belonged to a social group.
However, the identity of an animal’s mother did not play a role, suggesting behaviour that leads to isolation is not learned from the mother.
Dr Brent said the findings suggested isolation could be partly maintained by natural selection – meaning there might be some evolutionary benefits.
The possible benefits of isolation include lower risks of disease and conflict.
How many people are lonely?
An estimated 1.1 million over 65s in the UK are chronically lonely, figures suggest. A report this week revealed nine million adults suffer from ‘damaging’ loneliness – described as a ‘social epidemic’.
A recent study also suggested 72 per cent of Americans experience loneliness at some point.
Being chronically lonely leaves adults at risk of developing heart disease and dementia, according to studies.
An increased risk of death
Professor Jane Cummings, chief nursing officer for England, said this week: ‘Social isolation can have a devastating impact not only on people’s mental well-being.’
Speaking about the report, she added that ‘evidence shows that it can also increase the risk of premature death by around a third’.
Professor Helen Stokes-Lampard, chair of the Royal College of GPs, previously said social isolation is ‘akin to a chronic long-term condition’.
She said in October that the problem of many patients who GPs see isn’t medical – it’s that ‘they are lonely’.