Fans of woodpeckers and materials science will be thrilled to hear that MIT has just released a series of eight short-form videos explaining how woodpeckers can bang their heads against trees all day without suffering major brain trauma — or even getting so much as a headache. Called "Built To Peck: How Woodpeckers Avoid Brain Injury", the series features Lorna Gibson, MIT professor of materials science, who has been an avid birdwatcher for years. "I've long wanted to do a project on how birds work from an engineering perspective," Gibson said in statement. In the process, she got to visit natural history archives like Harvard's Museum of Comparative Zoology, which boasts drawers of preserved bird specimens, some dating back centuries.
Gibson isn't the first to be fascinated by this question: it's been the subject of numerous scientific studies in recent years, especially in light of growing concerns over concussions and long-term brain damage among professional football players. She's just found a fun and engaging way to delve into some of the key questions involved, such as how to make any measurements at all of a woodpecker's frenetic drumming. "I'd like to think you can dip your feet in, learn a bit of physics and mechanical engineering, and then want to watch more," she said.
About those earlier studies: Woodpecker heads are natural shock absorbers. They have to be, because the physical forces at play are formidable: a male woodpecker will peck between 500-600 times a day, 18-22 times per second — twice that during courtship season — with deceleration forces of about 1200 g. (The more slowly you decelerate, the less the impact, because the energy is dissipated over a longer period of time.)
For context, a human being would get a concussion with a sudden deceleration of 100 g. But woodpeckers? Yeah, they're fine.
As I explained in a Scientific American post about a 2011 paper on the subject:
[T]he key to protecting the pileated woodpecker from chronic headaches or more serious concussion had to do with the structure of their heads — "thick muscles, sponge-like bones, and a third inner eyelid," all of which work together to absorb impact — and the fact that woodpeckers make straight, clean linear strikes. ... Specifically, the beak is both hard and elastic, there is an area of spongy shock-absorbing bone in the skull, and woodpeckers have another springy structure in back of the skull called a hyloid. The skull structure works in concert with cerebrospinal fluid to further suppress vibrations.
Practical applications for this kind of research include building mechanical shock-absorbing systems to protect microelectronics in cell phones and aeroplane flight recorders, and for protecting spacecraft from floating "space junk". And sure, woodpecker and human heads are pretty different, anatomically speaking. But there's always the hope that we can learn something useful to, say, improve the design of football helmets to better prevent concussion.
Top image: Dick Daniels/Wikimedia Commons and carolinabirds.org