Each time a woodpecker drums on a tree to find food, build a nest, or attract a mate, it gets hit with up to 1,400 g’s of force—14 times the amount that would trigger a concussion in humans. Thankfully, the bird has a few ways to dampen the blow: built-in shock absorbers, an enlarged brain case, and a specialized beak and skull that redirect pressure away from its head. As if that wasn't enough, it can also wrap its tongue around the back of its head to serve as a cushion (when the organ isn't being deployed to trap dinner, of course).
These handy traits have inspired protective gear for concussion-heavy sports such as football and bike racing. The idea is simple: By modeling helmets and collars after a bird that's built to headbang, outfitters can decrease the risk of chronic traumatic encephalopathy (CTE), which is incredibly common in NFL players, as well as other brain diseases.
Or so the theory goes. While woodpeckers seem to fare okay in the long run, it's not known if their brains suffer from underlying damage.
“They’ve designed so much protective equipment based on the biomechanics of a woodpecker, but no one has ever looked at a woodpecker brain,” says Peter Cummings, a neuropathologist at the Boston University School of Medicine. “That just blew my mind.”
And so Cummings, a football dad himself, set out to change that. He and his colleagues George Farah and Donald Siwek secured 10 long-deceased woodpeckers (of different species) and five Red-winged Blackbirds from two museum collections. They then took up scalpels and removed thin slices of the specimens’ brains to test for deposits of an abnormal form of “tau,” a specific protein linked to neurodegenerative conditions such as CTE and Alzheimer’s.
The results, published in the journal PLOS One last week, surprised them. “I was thinking that there’s no way these woodpeckers would develop neurotrauma,” Cummings says. But his analysis revealed damaged, “phosphorylated” clumps of the protein in the woodpeckers’ brains. Blackbird brains, on the other hand, had no such deposits.
Tau, like most parts of the nervous system, is complicated. It can protect the passage of information between neurons, Farah says. But following repeated head trauma in humans, these proteins dislodge and accumulate in clumps that can slow the flow of information in the brain, resulting in cognitive and motor impairment. And that’s why finding similar buildups in the brains of woodpeckers—animals adapted to headbanging—was so unexpected.
But that doesn't necessarily mean that woodpeckers have brain damage. For starters, these are birds, not humans, so you can’t conclude that tau buildup is indicative of injury, let alone CTE.
And then there’s evolution. Woodpeckers have been drilling into trees for 25 million years; if that was causing symptoms like memory loss—which presumably would reduce the birds’ fitness—they would have shifted their behavior long ago. “Why would they still be pecking on trees if they are giving themselves neurodegenerative diseases?” Cummings says.
It’s also possible that the buildups serve an important function in woodpeckers’ brains. “If you’re going to be jabbing your head into something at 1,200 g’s, you’d want the neurons to be able to jostle,” Cummings says. “Could it be that this [build up of tau] has a neuroprotective effect?”
Without further research, Cummings’s guess is as good as yours (okay, maybe a little better). But just as there’s a lot left to be learned about bird brains, there’s much to be done to understand how exactly CTE works. Woodpeckers, Cummings says, could help shed more light on both fronts.