Laura Erickson's For the Birds

The trouble with being tiny–say chickadee size, weighing only as much as four pennies–is that you’re stuck with a tiny brain. Chickadees can live twelve years, and during every one of those twelve winters, they have to memorize a whole new set of hiding places where they stash away food supplies, and learn the habits of a whole new flock of acquaintances that they hang out for the season.

Now we humans are used to lugging around a heavy three-pound brain, which has enough memory storage space to deal with our year-to-year needs, but our brain has the unfortunate limitation that it simply can’t grow new neurons to replace old ones. The neurons that carry outdated, sometimes worthless memories hang around in our heads like so much dead weight, and I personally resent that while I have trouble remembering the names of people I’ve just met, I can still recite every word of the theme song to The Beverly Hillbillies.

Chickadees don’t have the luxury of wasting their valuable memory storage space on stuff they might as well forget the following year–you can only fit so many neurons into such a tiny brain. So they have a wonderful ability that we humans can only dream of: chickadees actually grow huge numbers of brand new neurons in the hippocampus–the part of the brain responsible for memory–throughout the year, throughout their entire lives, and the neuron turnover happens at an especially amazing rate during autumn, right when they need to memorize vast amounts of information to survive the winter.

The most curious thing about this extraordinary ability is that chickadees kept in captivity, and provided plenty of food throughout the year, regenerate brain cells at only half the rate of free-ranging chickadees, though they still grow plenty of new brain cells from year to year, which is more than we humans can say. This means that the individual chickadees can grow new brain cells to accommodate new memories whenever the need arises–imagine if university students could grow whole batteries of neurons while preparing for exams.

The bird brain neurobiologists who figured out all this come from Rockefeller University in New York and Tel Aviv University in Israel, and they hope their research on chickadee brain cell regeneration will eventually provide us humans with strategies for combatting paralysis and neurodegenerative disorders like Alzheimer’s and Parkinson’s diseases. Many other neurobiologists are less optimistic, figuring that although their work is interesting, chickadee brains are way too different from ours to be applicable.

For me, the magic of this kind of research is there even if it never has any applications for humans. I hardly ever look at a chickadee without marveling at how its bright eyes seem to look at the world as ever exciting and new. Of course, the individual chickadees that were subject to the experimenters’ scalpels probably didn’t look quite so bright and optimistic as they donated their brains to science, but at least the research proves how truly special and unique chickadees are. Perhaps it’s the chickadee brain, ever fresh and new, that keeps the chickadee’s outlook so cheerful and optimistic. Even beyond physiology, we humans could learn a few lessons from them.