Each boy raises the risk of death by 7 percent. They may be energetically more demanding to breast-feed
Boys can be a handful for both parents, but they only seem to take a toll on their mothers' life expectancy. Image: Melinda Brookshire Photography/Flickr
From Nature magazine.
Women who bear sons can have slightly shorter lives than those who bear daughters, researchers have found. Their study showed that a woman?s risk of death increased by 7% per year for each son born ? a small but statistically robust effect, at least for the individuals the team looked at ? Finnish villagers in pre-Industrial Scandinavia.
?Previous investigations into the effect of the gender of a baby on its mother?s lifespan have been mixed, so our new analysis really is just another brick in the wall,? says Samuli Helle of the University of Turku in Finland, the study's lead author. ?I?m not surprised the results have been mixed, because the previous studies have involved different societies, cultural practices and so on.?
A litany of factors could influence a woman?s lifespan, such as affluence and nutrition, as well as the number of children she has. The impact of having a boy compared with a girl is likely to be most pronounced in settings where resources such as food and health care are poor.
Helle and his co-author, Virpi Lummaafound, investigated parish records for individuals in eight parishes who lived during the seventeenth to mid-twentieth centuries. They found that if a woman in these communities was 37 years old at the time of having her last child, her life expectancy would vary depending on the sex of her children. She would live for another 33.1 years if she had no sons, another 32.7 years if she had three and another 32.4 years if she had six.
The study, which appears in Biology Letters, builds on previous research published by the same team in the journal Science more than ten years ago, which found that for every son she had, a woman's life would be shortened by an average of 34 weeks. By contrast, daughters actually lengthened their mother's lifespan very slightly (though not statistically significantly). In both studies, the life-shortening effects were experienced only by mothers, not fathers.
Biological factors
But the reason behind this small difference is the big puzzle. ?The relative importance of biological versus cultural factors remains an open question,? says Helle, who speculates that it could be that girls are more likely to help their parents in household duties. ?We need more data, such as how many sons versus daughters helped in everyday tasks, what age they actually started to work outside the home and so on.?
Erik Lindqvist of the Research Institute of Industrial Economics in Stockholm, who has looked at lifespan and births in Sweden, is not convinced. ?We have never been able to replicate their results," he says.
But Grazyna Jasienska, who studies longevity and reproductive health at Jagiellonian University Medical College in Cracow, Poland, believes that the effects of sons on a woman's lifespan are certainly real ? and are probably due to biological factors, such as breastfeeding.
Other studies have found that boys can take more of a toll on their mother biologically because they tend to be slightly heavier at birth than girls. And a few studies have found that women expend more energy in producing breast milk for boys ? although the results of such studies have been mixed.
?I think the costs of having boys over girls are more social than biological," she says. "But we still ultimately don?t know."
This story is reprinted with permission from Nature magazine. It was first published on February 27, 2013.
Source: http://rss.sciam.com/click.phdo?i=c4d51c7323eee3315a53eea3e7751f04
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MYO, the gesture control armband from Y Combinator-backed Waterloo startup Thalmic Labs, has managed to rack up over 10,000 pre-orders over the course of its first two days of pre-order availability. At $149 a pop, that means the young company has already managed to secure around $1.5 million in gross revenue, so long as they actually ship hardware.
No one likes a cluttered house. But, unfortunately, no one likes cleaning a cluttered house either, especially when it's so hard to keep clean. Take some times this weekend to declutter once and for all, and figure out an organizational scheme that works for you. 
Before you can have a truly organized house, you need to purge all the stuff you don't need. Before you do anything, form an attack plan. One of the best ways to declutter your home is to create a detailed inventory, and we've shared lots of solutions for doing so in the past. Once you've highlighted all the things you can downsize, it's time to get to work. Check out our guides on kicking your clutter habit for good and de-crapifying your home to get started. Your home office is probably its own beast, so be sure to dedicate specific time to that with our guide to getting out from under your office crap, and organizing those piles of paper into something manageable. Once you've gotten rid of the clutter you don't need, you'll be much better off when it comes to organizing everything else. Photo by Sandra Cohen-Rose and Colin Rose.
Now that you've gotten rid of the crap, it's time to organize the stuff you have left to make it more useful to you during your day. Once again, form a good plan of attack before you do anything else. Go through all your leftover stuff and make sure each item has a home. If you aren't sure where to put something, don't waste time on it. Put it in a clutter bucket that you can decide on after you're done with everything else. If you need help keeping everything clean, there are a lot of gadgets that can help, as well as stuff you probably already have lying around.
Once you've gone through all that work, you probably won't ever want to do it again, so now comes the (seemingly) hardest part: keeping everything clean and organized. It's much easier than it seems, though: in fact, by putting all those chores on autopilot, you can keep everything clean with what feels like minimal amounts of work. For example, instead of striving for perfection and going through big cleaning sessions every once in a while, just clean up 15 minutes a day. After 15 minutes, stop. You'd be surprised how quickly you get to perfection with such little effort. Every time you leave a room, take one item that doesn't belong there with you. And, every night, reboot your office to make sure you come back to a clean workspace in the morning. A few minutes a day is all it takes to keep everything clean and organized for the long haul, and once you've worked it into your daily routine, it'll be so easy to keep up you won't even notice you're doing it. Good luck!
start.? Every few weeks, either increase the time spent walking or the pace?which will increase the intensity of the workout.