China will have more than 23 million men unable to find wives by 2020 because so many more boys are being born than girls, according to a study…
These men are known as “bare branches” because they will never bear fruit. History suggests that they will give rise to higher crime rates and political instability. Their number might encourage China to become more authoritarian or seek an outlet for their energies through war.
For more on this research, see here. See also a July 2004 Washington Post article “‘Bare Branches’ and Danger in Asia“.