WIKIPEDIA, W.DJATMIKOUniversity College London’s Mario dos Reis and his colleagues presented evidence this week in Biology Letters to suggest that placental mammals originated while dinosaurs were dominant, contradicting a the conclusions of a Science paper published last year. Both groups performed extensive molecular clock analyses, yet arrived at different conclusions. According to dos Reis, the Science study was flawed because the researchers took the age of the oldest fossil from various placental groups to be the age of the group itself. But Maureen O’Leary from Stony Brook University, who led the study in question, countered, telling The Scientist that “the real test belongs in the field,” as researchers unearth more fossils.
“There’s nothing really wrong with either set of analyses,” said Olaf Bininda-Emonds from the University of Oldenburg, who was not involved in either study. “Both are robust. The real problem is that the methods are fundamentally different and make fundamentally different assumptions, so that there's little point in comparing the apples with the oranges.”
WIKIMEDIA, YTAKA TSUTSUMIIn a study of two populations of people in Columbia with distinct ancestry that are considered poster children for gastric cancer research, Barbara Schneider of Vanderbilt University Medical Center and her colleagues found that Helicobacter pylori strains that shared ancestry with their human hosts were less likely to cause severe disease. The researchers noted in PNAS this week that their work provides evidence of co-evolution between the pathogen and its human host.
“For the first time, [this study] suggests that we have to take the ancestry of both host and microbe into the equation,” said Emad El-Omar, a gastroenterologist and cancer biologist at the University of Aberdeen, who was not involved in the work.
WIKIPEDIA, ALVESGASPARAnt, bee, and wasp queens emit a similar class of pheromones that sterilize their workers, scientists have found, noting that this points to a potential shared ancestry for these chemicals. The University of Leuven’s Annette Van Oystaeyen and her colleagues presented evidence in Science this week to suggest that queen pheromones repeatedly evolved from chemicals found in the solitary ancestors of social insects.
