Women"s hair naturally grows longer than men"s hair. Paul reasoned from this fact that God intended for women to have more head-covering than men. People generally regard the reverse of what is natural as dishonorable. In the man"s case this would be long hair and in the woman"s case short hair. By "nature" Paul evidently meant how his culture felt about what was natural. [1] "Glory" means "honor."[source]
This is a very general observation. The fact that some acceptable men"s hairstyles are longer than some women"s does not mean these styles are perversions of the natural order. Men are usually taller than women, but this does not mean that short men or tall women are dishonorable. I understand that women"s hair generally grows fuller and faster due to the estrogen in women, whereas men"s hair tends to become thinner and fall out faster because of the testosterone in men. [source][source][source]