But this principle defies the matchmaking networks forced upon females by family, friends, employers and colleagues. That includes the groups of parents who gather in parks to swap stats on their children's economic statuses and physical attributes.
The expectation to marry while marketable pushes some women to preempt their "expiration dates" by marrying "beneath" them - that is, to poorer or younger men.
University of Hong Kong sociologist Sandy To says leftover women result from the persistence of China's patriarchal past. Many of these women have been rejected by men who feel more comfortable with less accomplished wives. Others struggled with relationships in which boyfriends expected them to spend less time at work and more on home life.
Take the recently publicized case of a Nanjing Normal University PhD student who sought a boyfriend to accompany her to her hometown during Spring Festival. Problem is, rather than celebrate smart as sexy, about 30 percent of Chinese men don't want to marry a woman with a PhD, an online Modern Express survey shows.
"These women are being forced to develop new strategies when it comes to courtship, dating and partner choice to avoid becoming shengnu," To says.
She researched the topic from 2008 to 2012 for her University of Cambridge doctoral thesis.
But early marriages often lead to divorces later.
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