Woodpeckers might hold key to saving our athletes’ brains
When it comes to headbangers, no Black Sabbath fan alive can outdo a woodpecker. Imagine smacking your head into a tree at 25 kilometres an hour, as frequently as 20 times a second, thousands of times a day, every day. That’s the woodpecker life. Sometimes woodpeckers drill into trees to snack on insects that have bored under the bark. Other times they excavate deep cavities in trees that they nest in. In 2015, an ornithologist filmed a desert woodpecker as it pecked through the skulls of mourning dove chicks to eat their baby brains.
Woodpeckers, despite all this hammering, seem to be fine. Fossils suggest the birds have been around for 25 million years without concussing themselves to extinction. This has led to the suspicion that the birds don’t suffer head injuries.
Yet a new report about woodpecker brain tissue raises the possibility that the birds do suffer some consequences. Maybe the woodpeckers are just fine behaviourally. But, to the scientists’ surprise, they have protein accumulations in their brains that resemble those found in athletes with head trauma.
“No one has actually ever looked at a woodpecker brain to see if it has any neurological issues,” said Peter Cummings, a neuropathologist at Boston University and a self-described “football dad.” Cummings collaborated with two other Boston University scientists: anatomist Don Siwek (who died in December) and neurobiologist George Farah, who performed the lion’s share of the laboratory work.
Farah obtained dead birds from the Harvard Museum of Comparative Zoolo- gy and Chicago’s Field Museum. He extracted the birds’ brains and sectioned them into paper-thin slices to examine under a microscope. He examined 10 woodpeckers. Five red-winged black birds, which do not hammer their heads against trees, provided the control samples. For each brain slice, he stained the tissue with molecules of silver.
Silver binds with high specificity to a protein called tau. “Tau is a normal protein in nerve cells.,” said Ann McKee, a neuropathologist at Boston University School of Medicine who was not involved with this research.
Tau comes in several types. But, after an injury, tau can change its form and clump up in toxic aggregations. Researchers have found tau in injured humans as well as bears, mice, squirrels and other animals, McKee said.
These tau accumulations are markers of a disease called chronic traumatic encephalopathy, or CTE. CTE is characterized by aggression, memory loss, confusion and depression, and it can progress to dementia. Autopsies of football players show “overwhelming evidence” that “prolonged exposure to repetitive head impacts” is associated with CTE, McKee said. McKee and her colleagues studied the brains of 111 NFL players. After postmortem examinations, 110 of the players were diagnosed with CTE.
Tau aggregations are linked to other neurological diseases, too, such as Alzheimer’s. But the protein is not a smoking gun. “It’s not specific for a mechanism of injury, but it’s indicative of something not being right,” Cummings said.
Farah’s silver stains revealed that none of the red-winged black birds, all adults, had tau accumulations. Eight of the 10 woodpeckers did, including a juvenile, the researchers wrote in a report published Friday in the journal PLOS One.
The results bore some similarities with human tau staining but were far from identical. “Nevertheless,” McKee said, “it’s an important and provocative finding.”
Cummings and Farah cautioned that it is not possible to conclude these accumulations are toxic. To diagnose CTE in humans, scientists look for accumulations in a specific part of a person’s cerebral cortex. Woodpecker and human heads, it should be said, are quite different. But we should care about what goes on in woodpecker brains, the authors of the new study said. As you watch 300-pound athletes heave themselves at each other during football matches, consider this: Woodpeckers are helping make football a safer sport. This research suggests woodpeckers have plenty more to teach us about brains, too.