Anti-dengue mosquitoes, ancient stallion genes and more in this week's news

Fiddler claws are cool
The storied, supersized claw of the male fiddler crab, a weapon of war and a lure in love, appears also to serve the prosaic function of keeping the males from cooking themselves while they’re out on the sand fighting and flirting. Males fiddlers grow one claw so large that waving it around is an athletic event and eating with it is basically impossible. Researchers from the University of Texas at Austin studied heat transfer in natural and declawed crabs of the Uca panacea species . The experiments, reported in the September American Naturalist, show that the monster claw may help in thermoregulation by radiating heat away from the crab during long stints on the sand. —Susan Milius

Anti-dengue mosquitoes released
The first test in real towns has shown promise for a strategy to combat dengue fever by releasing mosquitoes plagued with a disease of their own. The lab mosquitoes set loose in the new test carry a strain of Wolbachia bacteria, wMel, that renders mosquitoes highly unlikely to pass along dengue. The bacteria spread from mother to egg, and the infected lab mosquitoes succeeded in mating well enough with the wild population that bacteria ended up widespread among potential dengue-carrying mosquitoes in two towns in northeast Australia, researchers from the University of Queensland in Australia and their collaborators report in two papers in the Aug. 25 Nature. Dengue affects at least 50 million people a year, and there’s no vaccine. —Susan Milius

Ancient sulfur life
Scientists suspect early life liked to live off stinky sulfur chemicals, and fossil evidence may now support that idea. Western Australian rocks that date back 3.4 billion years contain the microscopic remains of ancient cells, say David Wacey of the University of Western Australia and colleagues. The fossils nestle among crystals of pyrite, an iron sulfide mineral that could be the metabolic leftovers of sulfur-munching life, the team reports online August 21 in Nature Geoscience. If confirmed, the work would represent some of the oldest fossils known.  —Alexandra Witze

A horse with no Y chromosome diversity
Stallions today have very little genetic diversity, but a new study of ancient DNA shows this wasn’t always so. Scientists have sequenced Y chromosome DNA, which is passed down by fathers only, from eight ancient wild horses and one ancient domesticated horse. The wild horses showed considerable genetic diversity, Sebastian Lippold of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and colleagues write online August 23 in Nature Communications. Something about the process of domestication may have decreased that diversity, the scientists suggest. —Alexandra Witze

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