Sheng nu cites studies that show that women are now breaking the tradition of "mandatory marriage" to have fewer children or marry later on in life. Other typologically similar terms that are still used in the modern lexicon of other countries and cultures show the concept has existed in some cases as far back as the 16th century. The term spinster was used to describe unmarried or single women of a marriageable age. It wasn't until 2004 when the Civil Partnership Act replaced the word spinster with "single" in the relationship history section of marriage certificates in the UK. Subsequently, at the
Eligible bachelor as an "eligible bachelor" chooses to be a bachelor, whereas an "eligible spinster" does not have a choice. Lakoff believes this use of language fosters, and grows from, sexual discrimination. Lakoff states "women are given their identity in our society by virtue of their relationship with men, and not vice versa." Another set of criteria that purports to determine a man's desirability to women is the "666 dating rule" or "rule of sixes", which are a set of minimum male qualities centred around the number six, namely a six feet height, a six-hundred horsepower car, six-pack abs, a six-inch penis,