Why don’t woodpeckers get concussions?

It’s a question that human beings have probably been asking since the first time they saw a woodpecker in action: How can something that repeatedly bangs its head against trees — or telephone poles or house siding — all day escape without brain damage? We thought it was because they basically had natural shock absorbers in their heads, but thanks to a new study with some high-tech imaging, we’re learning that may not be the case after all.

Sam Van Wassenbergh of Universiteit Antwerpen, Belgium, and a team set out to further study the shock absorber hypothesis because they weren’t quite convinced. Van Wassenbergh’s reasoning was that, by the basic laws of physics, shock absorption would be counterproductive to a woodpecker because it would dissipate kinetic energy and therefore reduce pecking force.

To study this theory, Van Wassenbergh and team turned to technology. Using cameras that recorded at 1,600 frames per second, they videoed 109 pecks by six woodpeckers from three different species. They then analyzed the footage in slow motion and used it to replicate the pecks with a biomechanical model built based on CT scans of woodpeckers’ heads. Using those biomechanical models, they were able to do a bunch of calculations and determined that woodpeckers don’t have serious built-in shock absorbers. Their working theory is that woodpeckers don’t get concussions because their brains are so small that they have a high concussion threshold, much higher than that of humans.

“The absence of shock absorption does not mean their brains are in danger during the seemingly violent impacts,” Van Wassenbergh said. “Even the strongest shocks from the over 100 pecks that were analyzed should still be safe for the woodpeckers’ brains as our calculations showed brain loadings that are lower than that of humans suffering a concussion.”