“Hey, Baby! I’m Feeling Great!” *cough cough* “Really!”
For the first half of the above video, a sick male zebra finch sits quietly on the floor of his cage. He’s not feeling so great, trying to rest and keep quiet while his immune system is in hyperdrive. But half an hour later, shown in the second half of the video, an unfamiliar female has entered the cage. To the male bird, that changes everything. He hops around with excitement and interest as if he didn’t feel sick at all.
Behavioral biologist Patricia Lopes of the University of California, Berkeley, and her colleagues injected this finch and others with bits of E. coli bacteria — triggering their immune systems without actually infecting them. They watched the birds as they lay sick, then compared how it behaved when a female was thrust into the picture, counting its hops and the time it spent resting. They found the male birds’ behavior changed completely, acting as if they weren’t sick in an effort to court the female.
This research, published online this month in the journal NeuroImmunoModulation, had a simple mission: What’s more important to these birds: The need to pass on their genes, or their health?
Evidently, getting laid is a priority over their own survival, which Lopes says could be tied to how desperate the finches are — the bid for sex could be a kind of Hail Mary pass at spreading their genes while they’re still alive. “If you think that you’ll survive to breed again maybe it’s not as important,” said Lopes. But if you think today is your last day, it could be very important. “In general what animals want is to pass on their genes. So maybe the best strategy is to mate.”
One hypothesis about what causes us and other animals to because lethargic when we’re sick is that it helps us conserve energy so that our immune systems can fight off the unwelcome invader. Bearing that in mind, the scientists also checked the brains of the finches for signs of Interleukin 1, a molecule that, when produced in the brain, makes animals chill out while the immune system fights. But they found that even the birds that got excited by a female visitor had high levels of Interleukin 1, meaning that something is overriding the orders from the molecule.
In the long term, this research could be used to generate ideas for how to alleviate symptoms in people from being sick. It’s also potentially useful, said Lopes, to understand what’s good for nonhumans who get sick. “Maybe for animals it’s nice to be in a group if you’re sick,” said Lopes. ”Or maybe it’s bad for their health, because they’re faking.”
Video credit: Patricia C. Lopes
Image credit: Wikimedia Commons/Peripitus
