Skip to main content

Mercury Poisoning Makes Birds Act Homosexual

Male birds that eat mercury-contaminated food show "surprising" homosexual behavior, scientists have found.

In a recent experiment in captive white ibises, many of the males exposed to the metal chose other males as mates.

These "male-male pairs did everything that a heterosexual pair would do," said study leader Peter Frederick, a wildlife ecologist at the University of Florida in Gainesville.

"They built their nest, copulated together, stayed together on a nest for a month, even though there were no eggs—they did the whole nine yards."

(Related: "Homosexual Activity Among Animals Stirs Debate.")

Wild white ibises—among the most common birds in Florida's Everglades—are exposed daily to mercury through their diets of crustaceans and other small invertebrates.

The prey animals take up mercury that's long seeped into the Everglades as a byproduct of industrial processes such as waste incineration.

Recent pollution-control measures have "grossly reduced" the contamination, Frederick said. Even so, the new study shows that ibises experience "fairly major reproductive problems at pretty low levels of [mercury]."
Contaminated Birds Produce Fewer Babies

During the five-year experiment, Frederick and colleague Nilmini Jayasena divided 160 young captive white ibises into four groups of equal numbers of males and females.

During the study period, male and female birds were allowed to choose their mates—an experimental first, according to the study authors.

"All other studies that involve reproduction in birds took a male and a female and put them in a cage," Frederick said. "Our finding, while novel, is the first time anybody's looked for it."

Starting at around 90 days of age, each of three groups was fed a diet containing either low, medium, or high amounts of mercury, based on a realistic range of exposures in the wild. A fourth control group ate mercury-free food.

Once the birds had reached sexual maturity at around a year old, homosexual bonding increased in all three groups exposed to mercury. This behavior led to a 13 to 15 percent decline in the number of young, compared to the mercury-free control group.

The metal also impacted heterosexual couples. Overall, female birds exposed to mercury yielded 35 percent fewer babies than the control group.

(Related: "Mercury Pollution's Oldest Traces Found in Peru.")

The biological mechanism for how the metal causes homosexual actions is not totally understood, Frederick added.

Mercury is a known endocrine disruptor—a substance that mimics or blocks the production of natural estrogen. In this case, exposed male birds' bodies produced more estrogen than testosterone as compared with control birds.

(See "Weed Killer Makes Male Frogs Lay Eggs.")

Though hormones can affect sexual behavior, estrogen or testosterone alone usually don't influence how a bird chooses a mate. This makes Frederick speculate that mercury exposure during the birds' sexual development may play a role.


Mercury Mysteries Remain

Many unknowns remain about the study and mercury's effects, Frederick warned.

The team did not have funding, for example, to examine whether taking mercury out of the birds' diets would stop the homosexual behavior.

But "my suspicion is none of the effects we saw are likely to be permanent," Frederick said. In general, mercury flushes from a bird's body within weeks if the animal isn't consistently exposed.

Frederick also emphasized that the study has no ramification for humans.

"There's a great tendency to extrapolate this study in an offhand fashion to mean, Oh if you eat mercury, you're going to be gay," he said.

In addition, the researchers can't say for sure whether homosexual behavior occurs in wild birds exposed to mercury. (See bird pictures.)

But at least one expert praised the white ibis study for showing a plausible effect of mercury poisoning in the wild.

One of the "great frustrations" for scientists is lab studies on environmental contamination that don't predict what happens in the wild, Lou Guillette, a zoologist at the Medical University of South Carolina, said in a statement.

"So a study like this that looks at environmentally appropriate levels of mercury is probably the most powerful kind of study to tell us what's going on in the real world," said Guillette, who was not part of the research.
Study author Frederick added that the research "gives us a very clear prediction to test—to get out and see whether there are males pairing with males in nature."

"This study badly needs to be replicated."


The homosexual-bird research was published online December 1 in the journal Proceedings of the Royal Society B.

source NGO

Comments

Post a Comment

Popular posts from this blog

Reasons Why Your Hips Hurt

Hips Don't lie Inside the Joint Each hip is a ball-and-socket joint. The ball is the top of your thighbone (femoral head). The socket (acetabulum) is in your pelvic bone. Smooth, slippery tissue called cartilage lets the ball and socket glide against each other when you move. A thin lining (synovium) tops the cartilage and makes a bit of synovial fluid, which further eases rubbing.  Tendons, ligaments, and muscles complete the joint. Osteoarthritis It’s the “wear and tear” type of arthritis that many people get in middle age. Cartilage on the ball end of the thighbone and in the hip socket slowly breaks down and causes grinding between bones. You’ll have stiffness, and you might feel pain in your crotch and at the front of your thigh that radiates to your knee and behind. It’s often worse after a hard workout or when you don’t move for a while. Rheumatoid Arthritis With RA, your immune system attacks parts of your body, which can include the syn...
Post a Comment
Read more

Anesthesia Before Age 2 Linked to Learning Problems

There are new concerns about an increased risk for learning problems in very young children exposed to general anesthesia during surgical procedures. Researchers from the Mayo Clinic in Rochester, Minn., found a twofold increase in learning disabilities in children who had more than one exposure to general anesthesia with surgery before age 2. The study is published in the November issue of Pediatrics. The FDA requested and funded the study. Last spring, an FDA panel met to review the research examining the effect of early exposure to anesthesia on the developing brain. Following the meeting, FDA director of anesthesia and analgesia products Bob Rappaport, MD, wrote that additional studies are needed. He noted that "at present, there is not enough information to draw any firm conclusions" about the long-term impact of early exposure to general anesthesia on the brain. The new study adds to the evidence linking repeated exposure to general anesthesia very early i...
Post a Comment
Read more

FDA: 5 Death Reports for Monster Energy Drink

  The FDA is investigating reports of five deaths and a nonfatal heart attack in people who drank high- caffeine energy drinks made by the Monster Energy Company. Meanwhile, a Maryland couple has filed a wrongful death suit against the company, alleging that their product killed their 14-year-old daughter. They say Anais Fournier, 14, collapsed after drinking her second 24-ounce Monster Energy drink in two days. She died six days later. The reports are not proof that the drinks caused the deaths, but merely signal there might be a problem. Even if the deaths are determined to be caused by caffeine poisoning, the FDA will consider all sources of caffeine before blaming the deaths on the energy drink. In addition to caffeine, energy drinks contain other stimulants, including taurine and guarana , a caffeine-containing plant. Because energy drinks are sold as nutritional supplements, they are not regula...
Post a Comment
Read more