We typically focus on the downsides of adding pollution to the environment and ways to avoid doing so, but a tidbit of news in yesterday’s New York Times weekly science section sheds an unusual light on toxins.

Scientists in Cardiff University found that worms feasting on sewage sludge, which were in turn making good snacks for starlings, had a positive effect on the males’ mating song. The worms accumulated estrogen that occurred naturally in the sludge and impacted the brain development in the birds.
“The researchers gave male wild starlings in the lab the same chemicals in doses similar to those in the wild and found that the brain area responsible for song complexity became overdeveloped and that the songs were more complex than in birds that did not have the compounds.”
Apparently the ladies like the more sophisticated tunes and are choosing the males who have been slurping up the tainted worms. But there’s a catch. Male courting songs have evolved as a means for females to judge the strength and fitness of their possible mate; presumably they choose the guy with the best genes. In this case, the toxins that improve his courting skills, “also affected immune systems, weakening fitness,” reported the Times article.

The findings remind us of that old truism: nature is a massive, massive web. Changing one thread affects others — sometimes for the worse, sometimes for the better. As for the feathered fellows, run, er, fly with it while you can. Given evolution’s track record, the ladies are sure to figure it out soon.

Story by Victoria Schlesinger. This article originally appeared in Plenty in March 2008. The story was added to MNN.com.

Copyright Environ Press 2008