Today, the average woman in the world bears half as many children as did her counterpart in 1972, and no industrialized country still produces enough children to sustain its population over time, Phillip Longman noted last summer in an article for Foreign Affairs. In the United States, the total fertility rate has dropped from 3.2 children per woman in 1920 to 2.1 children today. In Europe, fertility declined from 2.8 children per woman to 1.5 between 1970 and 2000.
Boldrin noticed that the decline in fertility in developed countries paralleled the development of state-sponsored pension programs. Coincidence? Boldrin and her research team thought not.
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Drawing from surveys and other data collected by previous researchers in the United States and Europe, including a massive cross-cultural study of 104 countries conducted in 1997, they were able to identify the factors that most directly influenced fertility rates. They also charted the growth of the old-age pension systems in each country to determine what impact, if any, they had on fertility. The development of government pension programs accounted for between half and two-thirds of the decline in fertility rates in the United States and developed countries over the last 70 years, they concluded in a new working paper published by the National Bureau of Economic Research.
But the long-term health of the U.S. Social Security system is looking increasingly shaky. Could this produce a baby boomlet?
Perhaps, their study suggests. In fact, it may already be happening. Births-per-female actually have bumped up slightly in recent years, they reported.
Coincidence? The Wiz thinks not.
A Healthy Edge for Inquisitive Rats
Curiosity killed the cat but apparently may help female rats survive some types of cancer, according to a Penn State University researcher.
Sonia A. Cavigelli, assistant professor of biobehavioral health, tracked the development of 80 female laboratory rats from birth to death. She found that the more curious ones with breast or pituitary tumors lived, on average, an additional six months -- or about 25 percent longer than their less inquiring sisters.
Cavigelli cautions that it's difficult to extrapolate from rats to people. But she said that studies of older Americans have found that more outgoing people report fewer health problems than shyer seniors.
She detailed the results at a recent meeting of the American Psychosomatic Society in Vancouver.
She did the study while a post-doctoral researcher at the University of Chicago with J. R. Yee, a graduate student in human development, and Martha McClintock, a professor of psychology.
But the Wiz has a question: How do you recognize a "curious" rat?
By watching them play on a rat playground, Cavigelli said.
The rodents were tested shortly after birth and then again as adults by placing them in an enclosure filled with unfamiliar objects, including tunnels, bricks, stones and a small box, Cavigelli reported.
Those that readily explored the new environment were labeled "curious." Those that refused to venture outside the bowl that was used to introduce them to the playground were designated "cautious."
morinr@washpost.com
