Ants use legs as pedometer to find their way home

INSECTS
Like a twist on the old children's rhyme, the ants went marching two by two -- some wearing stilts, others on stumps. Through an inventive experiment modifying ants' leg lengths, scientists have solved the longstanding puzzle of how these insects navigate back home, proving that ants use their stride as a ``pedometer" to measure distances. ``They sum up over the steps they have taken," said zoologist and study co-author Harald Wolf of the University of Ulm in Germany. After ants in the study walked to a feeder, Wolf's team glued slender pig bristles to some ants' legs (photo below) and cut off the lower leg segments of others. As they trooped back home, ants with lengthened legs overestimated the distance back to the nest and walked too far. Stumpy-legged ants, meanwhile, began searching for the nest entrance too early. Wolf said the procedure doesn't appear to hurt the ants, which often lose leg segments while foraging. ``They don't care. They just say, oh, great, food, and they run off," he said. The ants quickly adjusted to their new legs, and for days after the experiment, kept on stilting or stumping to dinner.

THE BOTTOM LINE: Ants use their stride to calculate distances, using their own step length as a pedometer. They're the first animals known to navigate by this method.

CAUTIONS: Visual cues or other sensory information may play a secondary, unquantified role in helping ants get home.

WHAT'S NEXT: Researchers want to learn how ants are so accurate in rough terrain. The findings may also aid design of walking robots.

WHERE TO FIND IT: Science, June 3, 2006.

NAILA MOREIRA

DIABETES

Disease can age patients' hearts by 15 years

Research from the University of Toronto has found that diabetes increases the risk of heart disease to the same extent as aging 15 years. The study relied on health records of 9,397,085 adults in Ontario, Canada, from 1994 to 2000, 379,000 of which had diabetes. The researchers calculated that, for people who already have other risk factors, men with diabetes develop a high risk of heart disease at an average age of 41 and women at 48. For both genders, that's 15 years earlier than in the non-diabetic population. Treatment guidelines for diabetics already recommend protective heart treatment such as prescribing aspirin and medications to lower cholesterol and blood pressure, but differ on the age at which to start such treatment. ``The general approach has been to assume everyone with diabetes is high risk, and to throw the book at them," said first author and endocrinologist Gillian Booth . ``We wondered if it makes sense to treat people in their 20s or 30s without knowing whether or not it's warranted." Though diabetics under 40 showed an increased risk of heart disease in this study, their average risks fell into the moderate or low category, suggesting that doctors should individualize protective heart treatment in this age group.

BOTTOM LINE: The findings support the American Diabetes Association guidelines recommending protective heart treatment in diabetes patients over age 40, and individualized treatment before that.

CAUTION: The researchers could not detect undiagnosed diabetes or identify all patients taking heart medications in their study population, nor could they differentiate between type 1 and type 2 diabetes.

WHAT'S NEXT: The researchers want to develop better ways to assess individual heart disease risk levels in young adults with diabetes.

WHERE TO FIND IT: The Lancet, July 1, 2006

ELIZABETH DOUGHERTY

HAPPINESS

Money is less important than friends

The rich may have lots of playthings -- luxury cars, clubhouse memberships, and vacations in tropical climes -- but the link between wealth and happiness is mostly an illusion, researchers report. An article published in the journal Science found that, contrary to popular belief, people with above-average incomes do not spend more time enjoying leisure activities. They also tend to be more tense than the the less-wealthy, and report being only slightly happier than others in their day-to-day experiences. Based on a survey as well as federal statistics on how people of varying incomes spend their time, the researchers found that simple everyday things have a strong affect on mood. ``One thing that is very important to raising people's happiness is to spend time with friends, and you don't need much money to do that," said Alan B. Krueger a Princeton University economist and a lead author of the study.

BOTTOM LINE: The commonly held belief that money buys happiness may not be true. ``When you look at how people live their lives moment to moment, income is vastly overrated in terms of generating happiness," Krueger said.

CAUTIONS: The current study focused primarily on women. Similar studies that define happiness in more general terms of overall satisfaction in life found a stronger correlation between income and happiness.

WHAT'S NEXT: Krueger and his colleagues are now conducting a larger nationwide poll of men and women that they hope will substantiate the current study.

WHERE TO FIND IT: Science, June 30, 2006.

PHIL MCKENNA