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Marked up barn swallows grow more testosterone
Researchers darkened male New Jersey barn swallows using a $599 marker, making lighter birds look darker and triggering a 36 percent rise in testosterone after one week. The study, in Current Biology, notes increased mating and questions how color signals affect physiology in birds and humans.
MENTIONED IN THIS ARTICLE
Washington, D.C
New Jersey
Smatest
Kevin McGraw
Arizona State University
McGraw
Current Biology
Rebecca Safran
University of Colorado In
Boulder
Safran