Study: Pollution causes homosexuality in birds

wrahn Contributor
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The nature versus nurture debate just took an unexpected turn — thanks to pollution.

Increased exposure to the toxic chemical mercury can affect sexual preference in certain species of birds — inducing homosexuality, a new study has revealed.

Peter Frederick, an ecologist from the University of Florida, and Nilmini Jayasena from the University of Peradeniya in Sri Lanka found that male American white ibises that consumed methylmercury, the most toxic and easily digested form of mercury found in the environment, were more likely to pair with other males. In wild ibis populations with no mercury exposure, same-sex pairing is non-existent.

“We knew that mercury was likely to affect reproductive hormones from an earlier study,” Frederick told, “so we suspected some aspect of reproduction would be affected, like whether the birds came into reproductive condition or whether they were too aggressive to pair.”

“We had no clue that mate choice might be involved,” he added.

Birds living in wetlands, such as the ibises, are most vulnerable because the environment is a breeding ground for bacteria that convert the mercury spewed from coal-fired power plants into methylmercury, which “is at least ten times as toxic as the stuff in a thermometer,” Frederick said.

Full story: – Pollution Causes Homosexuality in Birds, Study Shows