In fairy tales, the youngest child routinely turns up at the end as the smartest, bravest, and most deserving member of the family.
But according to the "confluence" model--the behavioral-science theory of birth order and intelligence that has prevailed recently--the youngest is likely to be less intelligent than his or her older siblings. This is so, according to Robert B. Zajonc and other psychologists who favor the theory, because the home environment becomes less stimulating as the family becomes larger.
Another psychologist, however, who has analyzed the link between family size and intelligence using 11,000 students from Brigham Young University, challenges the data. Richard Galbraith, who is on the university's faculty, found that family size either had no effect on intelligence, or that it has a slightly positive effect--that is, as family size increased, so did the intelligence of the children.
The age gaps between children, he found, do not shed any light on intelligence and birth order.
Mr. Galbraith's challenge has been met with a rebuttal by supporters of the confluence theory; both theories are reported on in the March issue of Developmental Psychology.
Childhood diseases like chicken pox that are seldom serious or life-threatening for normal children may represent a major threat to those children whose immune systems have been weakened--a common side-effect of many kinds of cancer treatment. Medical researchers, who have not developed a vaccine for chicken pox because the delayed side effects of the vaccine could be more serious than the disease itself, are taking special steps to protect these children from chicken pox.
In a study sponsored by the National Institute for Allergy and Infectious Diseases, 500 children in the U.S. and Canada who have leukemia (the most common childhood cancer) will receive "live, attenuated" chicken pox virus vaccine.
If the vaccine does protect them from the potentially lethal virus, it may also be valuable for children with other immune-system disorders.
Another pox made headlines recently when epidemiologists at the Centers for Disease Control (cdc) provided numbers to support the "widely held contention that an epidemic of genital herpes infection occurred in the United States between 1966 and 1979," the last year for which data are available.
The infection is notable for several reasons. It recurs; it has been associated with cervical cancer; and it can damage or kill newborn babies. Moreover, there is no cure; a teenager who contracts the infection now will remain infected until a cure is discovered--if a cure is discovered.
In 1966, physicians reported that 29,560 patients consulted them for genital herpes infections. In 1979, this number had jumped to 260,890.