Beards make the jawline seem bigger and as a result it makes the man look more masculine. Women tend to favor men who are more masculine over other men.
Beards take a time to grow and as a result it requires a lot of patience. A man who manages to wait until his beard grows is usually a patient man (see why people are patient).
Because a man sometimes has to go through some stages where the beard will look bad on him until it grows usually men who are confident about their looks grow beards.
Women favor men who are capable of both protecting them and their offspring. Because a beard in many cases makes the man look more intimidating it can make women think that the man is strong and brave (see how to tell if someone has high testosterone).
Beards can make men look more mature. Some men who have a baby face look much more mature after they grow a beard. Because women look for men who can support the family a more mature looking man is usually more preferred.
Women usually favor bad boys over nice guys. A beard can easily help a man achieve the bad boy look in some cases.
Some studies have claimed that beards make men believe that their faces have grown bigger. Such a belief can psychologically make the man feel stronger and more in control.
Beards can make some men look rebellious. The fact that a man goes against the popular norms to grow a beard shows that might have a rebellious nature, a trait that is usually favored by women.
At times or places where beards are not main stream the man who grows a beard is usually a confident one. It takes a lot of confidence and courage to be different and many cases a man who grows a beard is both brave and confident.
According to a study Beards block most of the harmful UV rays thus preventing many health issues and keeping the skin healthy. Beards can make men healthier.
When a woman sees a man with a beard she might unconsciously recall Che Guevara, old medieval warriors or a viking leader. The fact that the human mind works by associations makes it more likely that a woman remembers other people with beards when she sees one of them.
Studies have shown that women tend to prefer the older man over the one of the same age provided that everything else is constant. Beards can make men look more older and mature.
People were conditioned to believe that a beard makes men wiser. Kings, monks and wise men who appear on movies usually have beards. This helped create the association between beards and wisdom.
Because beards make men look strong, powerful, confident and intimidating other men are more likely to respect them.
Beards require a lot of commitment to be grown. Because women prefer men who have commitment over others they might find a man with a beard more attractive.
One theory states that disease carrying parasites live in body hair. According to that theory if a man has a beard and is not sick then this might mean that he has a strong immune system.
Some studies have found that beards were found to be attractive when they were rare. In other words when most people shave a man with a beard might look more attractive because it helps him stand out from the crowd.
Beards are a secondary sexual characteristic, they signal that a man went through puberty both physically and mentally. Shaving a beard might indicate that a man is uncertain in his adult role and thus unintentionally signaling he's a less desirable partner to women.
Some people associate a man's beard with a lion's mane. Since lions are depicted as kings of the animal world, people associate that those with beards have some of lion's best characteristics - nobility, being proud, brave and so on.