Science

Researchers have found that some species of army ants in Central and South America can use their bodies to fill potholes on the road to a food source.
Researchers have found that some species of army ants in Central and South America can use their bodies to fill potholes on the road to a food source. (By Scott Powell -- University Of Bristol)
Monday, May 28, 2007

Ocean Temperatures Not the Only Determining Factor in Hurricanes

The eastern Caribbean has experienced periods of intense hurricane activity during centuries of unusual cold as well as unusual warmth -- suggesting that ocean temperatures are not the only, or most important, factor determining how the storms are spawned and how strong they become.

Researchers at Woods Hole Oceanographic Institution in Woods Hole, Mass., came to that somewhat surprising conclusion by analyzing coarse, sandy deposits at the bottom of a lagoon on the Puerto Rican island of Vieques and in the New York area. That work, which allowed them to produce a 5,000-year record of hurricane activity, found a strong correlation between the intensity of storms along the Atlantic coast and the strength or weakness of the El NiƱo water temperature effect in the Pacific Ocean, as well as the intensity of West African monsoons.

The findings add to the complex puzzle scientists are trying to solve regarding the origins of especially destructive hurricanes. Some believe that the warming of ocean temperatures, as a result of greenhouse gases set loose by human activity, has led to stronger and more destructive hurricanes, while others say the data do not support that conclusion.

In their paper in the journal Nature, Jeffrey P. Donnelly and Jonathan D. Woodruff conclude that the issue remains unsettled -- that the occurrence of intense hurricane activity even when global and ocean temperatures are relatively low does not necessarily mean that global warming will not lead to greater hurricane dangers. Rather, they say it means that patterns of hurricane intensity can change significantly without a global ocean temperature rise, and that with the increase the effect could be greater.

-- Marc Kaufman

Some Army Ants Are Capable Of Using Bodies to Fill Potholes

Some ants are just unlucky.

Researchers at the University of Bristol, in England, have discovered that some species of army ants in Central and South America have an occupational specialty that consists of using their bodies to fill potholes on the road to a food source. This allows thousands of their fellow foragers to make better time by walking over them.

Scott Powell and Nigel Franks drilled holes of varying sizes in a wooden plank that simulated a narrow route through the leaf litter. They found that army ants, Eciton burchellii, which range from 3 millimeters to 12 millimeters long, found holes in the plank that matched their size and lay down in them.

The predatory ants, whose raiding parties can number 200,000 individuals, are able to move more prey per unit time over a "repaired" road than over a rutted one.

Despite the loss of ant power that comes from assigning many individuals to be living pothole filler, that ultimately improves the fitness of the whole colony, which can include up to 2 million ants.

"When the traffic has passed, the down-trodden ants climb out of the potholes and follow their nest mates home," Powell said in a statement accompanying the study in the journal Animal Behaviour.

Some of them, presumably, limp.

-- David Brown

More Genes Discovered That May Contribute to Breast Cancer Risk

Scientists reported yesterday that they had discovered several additional genes that may contribute to the risk of getting breast cancer -- discoveries that, if confirmed, could someday lead to better screening tests and treatments.

Breast cancer risk is in part inherited, but the genes responsible are largely unknown. Rare mutations in two genes, BRCA1 and BRCA2, account for less than half of the inherited part of breast cancer prevalence. Many scientists suspect that the remaining parts are spread among scores of other genetic mutations that are probably much more common than BRCA1 and BRCA2 but individually contribute a much smaller degree of risk. That makes them more difficult to find, since many people who have them will not get cancer.

In one of the new studies, researchers at Harvard University and the National Cancer Institute used blood samples to compare the genetic makeup of about 3,000 women with breast cancer against about 3,000 healthy counterparts. Of more than half a million mutations -- or "gene variants" -- studied, one in particular, called FGFR2, appeared to contribute significantly to breast cancer risk. It is notable because the risky variant exists in up to 60 percent of women of European descent and can increase risk by 20 percent to 60 percent compared with women with the safer variant, the team reported in yesterday's online edition of the journal Nature.

BRCA1/2 raises breast cancer risk by about 900 percent.

Related research in yesterday's online edition of Nature Genetics offers evidence for contributions from a handful of other genes as well. But researchers said it is too soon to think about testing women for the genes because the results are still preliminary, and, to be meaningful, any test would have to include a combination of many of the low-risk genes.

-- Rick Weiss


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