Having poor looks and being short or bald, followed by lack of confidence could be reasons why a large number of men remain single, a study has showed.
A team led by Menelaos Apostolou from the University of Nicosia in Cyprus anonymously asked men on social news aggregation and discussion website Reddit "Guys, why are you single?"
The findings indicated that most of the men who responded were not willingly single but wanted to be in a relationship.
The team assessed 6,794 of the 13,429 comments that were received and whittled down the top 43 reasons why men were single.
Poor looks and being short or bald were the most frequent reasons they put forward, followed by lack of confidence.
Not making the effort and simply not being interested in long-term relationships were also high on the list, along with a lack of flirting skills and being too shy.
Some said they had been so badly burnt in previous relationships that they did not dare to get into another. Others felt that they were too picky, did not have the opportunity to meet women or had different priorities.
Some of the men had experienced mental health issues, sexual problems or struggled with illness, disability or addiction, the researchers noted, in the paper published in the journal Evolutionary Psychological Science.
In the past, forced or arranged marriages meant that socially inept, unattractive men did not have to acquire social skills in order to find a long-term love interest. Today, men must be able to turn on the charm if they want to find a partner.
"Single modern men often lack flirting skills because in an ancestral pre-industrial context, the selection pressures on mechanisms which regulated mating effort and choosiness were weak," Apostolou explained.
"Such skills are needed today, because in post-industrial societies mate choice is not regulated or forced, but people have to instead find mates on their own," he added.