A new study led by the University of Colorado at Boulder has shown the testosterone of male North American barn swallows skyrocketed early in the breeding season when their breast colors were artificially enhanced by researchers, indicating the clothes -- or in this case, the feathers -- make the man.
The swallows, whose breast feathers were darkened to a deep red known to be most attractive to females, likely had more testosterone racing through their bodies because of amorous interactions with the opposite sex and more run-ins with jealous males, said CU-Boulder Assistant Professor Rebecca Safran, lead study author. The jump in testosterone was unexpected because it was observed at the time in the breeding cycle when levels of sex steroids like testosterone are typically declining, she said.
Lees meer: Biology News Net
The swallows, whose breast feathers were darkened to a deep red known to be most attractive to females, likely had more testosterone racing through their bodies because of amorous interactions with the opposite sex and more run-ins with jealous males, said CU-Boulder Assistant Professor Rebecca Safran, lead study author. The jump in testosterone was unexpected because it was observed at the time in the breeding cycle when levels of sex steroids like testosterone are typically declining, she said.
Lees meer: Biology News Net
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