Promiscuous Penguins from an Evolutionary Standpoint

Promiscuous people are sometimes described as wanting sex with “anything that moves”, but according to one polar naturalist, adelie penguins take their lack of discrimination a step further. Newly uncovered notes taken a century ago by George Murray Levick reveal that some male penguins had sex with females who happened to be dead.

The story appears to have been broken by the BBC but has been widely circulated by this point. The penguin sex diary notebooks were the accidental discovery of Douglas Russell, curator of eggs and nests at the Natural History Museum in London.  Read the whole story here.
Here’s Russell quoted by the BBC:

"It's just full of accounts of sexual coercion, sexual and physical abuse of chicks, non-procreative sex, and finishes with an account of what he considers homosexual behaviour, and it was fascinating."

Some readers commented that they were surpised to see so much non-procreative sex among non-human animals. But this shouldn't be surprising. Other animals have sex-drives and pleasure centers. If anything, what's unique to humans is probably the practice of family planning – whether the plan is to have a family or not. I’m not sure there are any other animals that would voluntarily go to a fertility clinic and pay to be prodded by people in white coats.

Apparently our Antarctic naturalist used terms like “depraved” to describe some of the penguin behavior he observed, especially the consorting with dead bodies, but as Russell notes to the BBC, this is just an artifact of the male penguin sex urge. “It is the males seeing the positioning that is causing them to have a sexual reaction.”

That is, seeing another penguin lying down signals either that it’s a sexually receptive female or it’s an ex penguin.

While reporting my own penguins sex stories over the years, I learned that some penguin species show no discernible difference between males and females, and so positioning may be a key clue that they use to signal their own sex and read that of others. Looking through the archives I discovered not one but six stories I’ve written that contain the words “penguin” and “sex.”  The one that touched on the lack of penguin sexual dimorphism was a 2005 column that offered a scientific look at the film March of the Penguins:

The stars of March of the Penguins seem to endure the worst of all worlds: almost nonexistent sex lives that nonetheless lead them to parenthood, total self-sacrifice, and endless suffering.
Conservatives are loving it.
"It demonstrated qualities of sacrifice and devotion and the importance of child rearing and bringing the next generation into the world," says Michael Medved, who hosts a conservative radio talk show in Seattle. He said this was the first movie many of his listeners had seen since The Passion of the Christ. 

The film glossed over the fact that most penguins start fresh with a new mate every year. Further down in the column, I quoted naturalists who said that among emperor penguins anyway, the sexes are very hard to tell apart.

In fact, scientists are mystified as to how the penguins themselves figure out which sex they are, says John Rowden, a curator at the Central Park Zoo. To humans they're identical, even if you look between their penguin legs, where they all sport an opening called a cloaca. When opposite-sex penguins rub their nether regions together, the male squirts semen from his cloaca into hers. 

In zoos, genetic tests can distinguish the sexes. That's how curators at Central Park discovered that some of their penguins are gay - or at least having gay sex. "We currently have a number of same-sex pairs," Rowden says. Other birds in the wild sometimes form same-sex pairs. Given the situation with penguins it's impossible to tell whether any of the birds in the film were boy-boy or girl-girl couples that stole or adopted eggs. 

Not that conservatives are the only ones reading things into penguin sexuality. Many New Yorkers latched onto one particularly devoted gay penguin couple, Roy and Silo, who live at Central Park Zoo. 

But they were not as gay or as devoted as they appeared. After a six-year relationship they went their separate ways, and Silo now has a girlfriend. 

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