Hailing From the Same Planet

Men and women may not be from such totally different planets after all, according to a new analysis.

For a report published in the September issue of the journal American Psychologist, Janet Shibley Hyde of the University of Wisconsin in Madison reviewed 46 "meta-analyses" of research into psychological differences between the sexes conducted over the last 20 years.

"The mass media and the general public are captivated by findings of gender differences," wrote Hyde, citing popular books such as John Gray's "Men Are From Mars, Women Are From Venus." "I advance a very different view."

Hyde found that, from childhood through adulthood, males and females are much more alike than different for most psychological variables, including cognitive abilities, verbal and nonverbal communication, social traits such as leadership, and measures of well-being such as self-esteem. The only differences Hyde could find were in some physical abilities, such as throwing, some aspects of sexuality, and perhaps heightened physical aggression among men, although even that was unclear.

The widespread misconception that men and women are so different can have profound adverse consequences, Hyde said.

"It is time to consider the costs of overinflated claims of gender differences," Hyde wrote. "Arguably, they cause harm in numerous realms, including women's opportunities in the workplace, couple conflict and communication, and analyses of self-esteem problems among adolescents."

-- Rob Stein

Fetuses Seem to Cry at Noise

Fetuses appear to cry when disturbed, according to research that could overturn longstanding assumptions about behavior in the womb.

Researchers made the unexpected discovery while using ultrasound imagery to document fetuses' reactions to brief noises. They noted that some fetuses as young as 28 weeks responded with a series of intense inhalations and exhalations, an opening of the jaw, stiffening of the tongue and depression of the chest. This activity typically ended after about 20 seconds with an exhalation and a settling, often followed by a few mouth movements and a swallow.

"You can even see the chin and the bottom lip quiver," said Ed Mitchell of the University of Auckland in New Zealand, who with two coworkers described their observations in the September issue of Archives of Disease in Childhood: Fetal and Neonatal Edition. "I cannot believe it is anything but crying."

Fetuses do not breathe air but inhale and exhale amniotic fluid. Prematurely born babies as young as 25 weeks of gestation can cry immediately after birth, indicating that the physical capacity is present.

Mitchell said he is not sure what the finding says about a 28-week fetus's capacity to consciously interpret pain -- an issue that has recently gained attention in light of efforts to require that anesthesia be given to fetuses about to be aborted. It is widely accepted that the brain connections needed to experience pain are fully wired by 30 weeks of gestation, and perhaps by 25 weeks or earlier, Mitchell said.

If fetuses do cry, he added, the cries are silent -- there is no air to flow past the developing vocal cords.

-- Rick Weiss

Nuclear Tests Help Estimate Age

"CSI" fans, take note. Estimates of a body's age at the time of death may soon be much more accurate, thanks to an odd legacy of aboveground nuclear bomb tests of the 1950s and '60s.

The Cold War testing produced fallout that sharply increased levels of radioactive carbon-14 in the atmosphere, but since the Test Ban Treaty of 1963 (and for a long time to come), those concentrations have been dropping at a known rate.

Like other forms of carbon, the isotope reacts with oxygen to form carbon dioxide, which gets taken up by plants via photosynthesis.

People who eat vegetables end up with the same concentration of carbon-14 in their bodies as in the plants and the air. But because tooth enamel forms only once, it becomes a permanent record of the concentration at the time, and that can be measured. And because teeth develop at predictable ages until about age 12, knowing what year a tooth formed provides a good estimate of a person's age.

Researcher Jonas Frisen of Stockholm's Karolinska Institute, with colleagues in Sweden and California, tested the method on 22 people, and they were able to gauge their ages to within about 1.6 years. That's more accurate than current methods based on bone development and tooth wear.

Only one problem: People born before 1943 had formed all their teeth before the testing began. For them, all that this method can determine is that, as of now, they are at least 62. But that, the researchers wrote in the Sept. 15 issue of the journal Nature, they know "with a high degree of certainty (100 percent . . .)."

-- Nils Bruzelius

A 3-D sonogram printout shows the image of a fetus in the womb. Researchers find that the fetus shows signs of crying when disturbed by noise.