At some point over the past generation, people around the world entered what you might call the age of possibility. They became intolerant of any arrangement that might close off their personal options.
The transformation has been liberating, and it's leading to some pretty astounding changes. For example, for centuries, most human societies forcefully guided people into two-parent families. Today that sort of family is increasingly seen as just one option among many.
The number of Americans who are living alone has shot up from 9 percent in 1950 to 28 percent today. In 1990, 65 percent of Americans said that children are very important to a successful marriage. Now, only 41 percent of Americans say they believe that. There are now more American houses with dogs than with children.
This is not a phenomenon particular to the United States. In Scandinavia, 40 percent to 45 percent of the people live alone. The number of marriages in Spain has declined from 270,000 in 1975 to 170,000 today, and the number of total Spanish births per year is now lower than it was in the 18th century.
Thirty percent of German women say they do not intend to have children. In a 2011 survey, a majority of Taiwanese women under 50 said they did not want children. Fertility rates in Brazil have dropped from 4.3 babies per woman 35 years ago to 1.9 babies today.
These are all stunningly fast cultural and demographic shifts. The world is moving in the same basic direction, from societies oriented around the two-parent family to cafeteria societies with many options.
This global phenomenon has been expertly analyzed in a report called "The Rise of Post-Familialism: Humanity's Future?" written by a team of scholars including Joel Kotkin, Anuradha Shroff, Ali Modarres and Wendell Cox.
Why is this happening? The report offers many explanations. People are less religious. People in many parts of the world are more pessimistic and feeling greater economic stress. Global capitalism also seems to be playing a role, especially, it seems, in Asia.
Many people are committed to their professional development and fear that if they don't put in many hours at work they will fall behind or close off lifestyle options.
Toru Suzuki, a researcher at the National Institute of Population and Society Security Research in Japan, gave Kotkin's team this explanation in its baldest form: "Under the social and economic systems of developed countries, the cost of a child outweighs the child's usefulness."