Mothers who have complained through the centuries that their sons will be the death of them may be right — a Finnish study shows having boys shortens a woman’s life span. Each son takes an average of 34 weeks off a woman’s life, says evolutionary biologist Samuli Helle. On the other hand, having daughters adds, but only very slightly, to a woman’s life span.
Helle was trying to prove that having large families can cause women to die early. But his study of church records among the Sami people of northern Scandinavia found that family size did not reliably predict that a woman would die young. He says, “We found that maternal longevity was not related to the total number of children born or raised to adulthood?”
Helle and colleagues looked at birth and marriage records of Sami people from 1640 to 1870. “These Sami depended mainly on reindeer herding, fishing and hunting for their livelihood and experienced natural mortality because of a lack of advanced medical care,” the team says. They only looked at women who lived to be over 50, and took into account whether a woman’s husband had died, since raising a family alone would be stressful. “Our results suggest that giving birth to sons had a higher relative long-term survival cost for mothers than giving birth to and raising daughters.?
There could be biological reasons for this. Studies show boys are physiologically more demanding to produce — they grow bigger and faster in the womb, and some studies show it takes a woman longer to get pregnant again after having a son than after having a daughter. Recent studies have shown that estosterone produced by the fetus could suppress the mother’s immune system and perhaps make her more susceptible to disease.
“There is no reason to believe that this effect would be only visible in Sami people,” Helle says. “Generally, boys get on their mothers’ nerves more than girls because they are running around, and girls are more willing to help their mothers.”
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Julia Scheeres writes in wired.com that two companies have announced plans to launch personal GPS “location devices” this year, which can act as electronic babysitters for harried moms. One is a bracelet, which parents can lock on their kids’ wrists to track their location and movements over the Internet. Another is an implantable GPS device.
The GPS is already used to track parolees, and the company making the device is being inundated with requests from Latin America and Asia for an application that can keep track of potential kidnapping targets. Between 1992 and 1999, kidnappings for ransom have jumped 70 percent worldwide.
ADS already distributes another GPS device in Latin America called ?Digital Angel,? which includes a watch and a pager-like device that clips onto a waist band; the company plans to combine the separate units into a single bracelet by the end of the year. But watches and other external devices can be easily removed by kidnappers, says the manufacturer, and in “such cases, an imbedded device would prove very useful.”
The dimensions of the implantable GPS “personal location device” would be about two inches in diameter and a half-inch thick, smaller than a pacemaker. Like a pacemaker, the device would be implanted in the upper clavicle area.
Wherify, of Redwood Shores, California, has developed a bracelet that combines GPS and wireless technologies to allow parents to plot their kid’s location and movement on a map over the Internet. The device, which costs $400 plus a monthly $25 service fee, can be locked onto the child’s wrist. The company plans to launch the product by summer’s end and is developing similar GPS location devices for adults.
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Should you breast feed? Breast-fed babies may grow up to be smarter adults, according to research that has found evidence linking nursing and intelligence.
In their study of 3,253 Danish men and women, June Machover Reinisch, of the Kinsey Institute for Research in Sex, Gender and Reproduction, and her team found that the more babies were breast-fed through 9 months of age, the higher they scored on intelligence tests in their late teens and 20s. Breast-feeding past 9 months had no additional effect on scores. Previous studies did not measure breast-feeding’s effects on IQ into adulthood, and the few that did ignored factors such as parents’ education and social status, say the researchers, who took these variables into account.
The link can probably be explained by the effect of nutrients in mothers’ milk on the developing brain and benefits from the close physical and psychological relationship breast-feeding involves. Mothers who take time to breast-feed may spend more time interacting with their youngsters throughout childhood, which also could affect intelligence.
Children who had been breast-fed for seven to nine months scored an average of about six points higher on IQ tests than those whose mothers said they nursed for less than one month.That gap “is not the difference between an Einstein and a mentally retarded child,” say the researchers. But it could be the difference “between normal and bright-normal, or bright-normal and superior.”
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Just one hour of exercise a day could transform the health of your children, not just now but well into their adult lives. Figures published by the British Heart Foundation show that one in three children between the ages of two and seven do not achieve even the minimum recommended levels of exercise.
By the time they are 15, almost two thirds of girls do so little exercise that they are classified as “inactive”. In the past 10 years, the number of obese six year olds has doubled while the number of obese 15 year olds has tripled. Experts believe that just an hour of exercise a day can help to fight obesity in children, which in turn can fight diabetes and heart disease later in life and even premature death.
They warn that many of the key risk factors for coronary heart disease can be seen at an early age. Conditions such as high blood pressure are common in children who are overweight or obese and are a major contributory factor to later coronary heart disease. Many believe that the key to encouraging more children to take up exercise is to ensure they participate in physical activity at an early age.
Dr. Joanne Wellsman, a senior research fellow at Exeter University and expert in children’s health, says, “Instilling an activity habit in children when they are young is vital.”
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Just a little bit of secondhand smoke can cause a lot of damage to a child’s learning ability, affecting reading, math and reasoning. More than 13 million children breathe in enough secondhand smoke to be affected in this way, says Kimberly Yolton of the Children’s Environmental Health Center at Cincinnati Children’s Hospital. “This study provides further incentive for states to set public health standards to protect children from exposure to environmental tobacco smoke,? she says.
Yolton and her team looked at data taken between 1988 and 1994 for the National Health and Nutrition Examination Survey conducted by the National Center for Health Statistics. The survey collects information about the health and diet of people in the United States. As part of the survey, people give blood and fill out detailed questionnaires. Some of the children took tests that show learning ability. Yolton’s team looked specifically for levels of cotinine, a substance produced when nicotine is broken down by the body. Cotinine, found in blood, urine, saliva and hair, is considered the best marker of environmental tobacco smoke exposure. They searched for children with very low levels of cotinine in their blood — below 15 nanograms per milliliter of blood.
They ended up with 4,399 children aged between 6 and 16 who had low levels of cotinine and who said they had not themselves smoked any cigarettes for the past five days. The more cotinine that children had in their bodies, the lower, on average, their reading, math and reasoning scores were. “Reading was the strongest effect we saw,” Yolton says.
“It is hard to say what is doing it because there are so many chemicals in tobacco smoke,” she says. Yolton said 43 percent of U.S. children are exposed to environmental tobacco smoke in their homes, and 85 percent of children have detectable levels of cotinine in their blood. “We estimate that more than 13 million children in the United States are exposed to levels consistent with the adverse effects seen in this study.”
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