Are woodpeckers giving themselves brain damage?
Humans can sustain a concussion from a force as low as 60 G's, and if head trauma occurs continuously over the course of years – say, from a career playing American Football – then permanent and devastating brain injuries can follow. But the humble woodpecker inflicts forces of over 1,000 G's on itself regularly, so how does it protect itself from brain damage? According to a new study, it doesn't.
Woodpeckers have a range of safety measures built into their skulls and heads. The bird's beak, skull and other bones are all finely tuned to absorb and redirect shock away from the brain, and these have inspired helmet designs like the Kranium.
"There have been all kinds of safety and technological advances in sports equipment based on the anatomic adaptations and biophysics of the woodpecker assuming they don't get brain injury from pecking," says Peter Cummings, an author of the new study. "The weird thing is, nobody's ever looked at a woodpecker brain to see if there is any damage."
So, the researchers decided to do just that. They studied pickled bird brains from the Field Museum and the Harvard Museum of Natural History, comparing the brains of Downy Woodpeckers with a control group of Red-winged Blackbirds – similar animals that don't put themselves through that kind of head trauma.
The scientists were looking for a build-up of tau proteins in the woodpecker brains. These proteins can be found wrapped around the axons in the brains of many animals, and in certain amounts they serve to protect and stabilize these fragile connections. But in human brains, an excessive amount of tau proteins is a sign of brain damage, having been associated with injuries often seen in football players, and neurodegenerative diseases like Alzheimer's.
The researchers took very thin slices of the woodpecker and blackbird brains, then stained them with silver ions to highlight the tau proteins. Sure enough, the woodpeckers' brains had far more tau proteins than the blackbirds. That may sound like an open-and-shut case, but the researchers caution that just because these proteins are associated with brain damage in humans, it might not be the same for the birds. After all, why would they evolve the ability if it was causing them harm?
"The earliest woodpeckers date back 25 million years — these birds have been around for a long time," says Cummings. "If pecking was going to cause brain injury, why would you still see this behavior? Why would evolutionary adaptations stop at the brain? There's possibility that the tau in woodpeckers is a protective adaptation and maybe not pathological at all."
If that is the case, the scientists say that further research could eventually help us develop new ways to protect the brain from injury, or slow the progression of neurodegenerative diseases.
The research was published in the journal PLOS ONE.
Source: Field Museum