Woodpecker Tongue & Concussion Prevention

How an intriguing biological hypothesis incorrectly became a cultural truth — and what it teaches us about navigating science and technology.

For years, I have heard a fascinating explanation for why woodpeckers can repeatedly strike their heads against trees without sustaining the type of brain injury we might expect in humans. The story usually goes something like this:

A woodpecker has an extraordinarily long tongue that wraps around much of its skull. This unusual structure acts almost like a seat belt or shock absorber, helping protect the brain from the tremendous forces generated during pecking.

An additional nugget of information providers further elucidation: the woodpecker's unusual tongue anatomy also partially compresses its jugular veins during pecking. This impedes venous outflow from the brain, increases intracranial blood volume, and creates a tighter fit between the brain and the skull—reducing the amount the brain can move during impact.

I remember listening to this explanation at a neuroscience conference with fascination at nature’s brilliant design. Apparently, I wasn't alone.

But when I recently revisited this literature, I discovered something that has become increasingly familiar during my years studying neuroscience:

The story I had learned was compelling, memorable, and beautifully intuitive. It was also incorrect.

2012: From Woodpecker Hypothesis to Rat Experiment

What protects the woodpecker brain from the forces generated during pecking?

One group of researchers decided to put this woodpecker-jugular-vein-compression theory to the test. Only, they didn’t do it in woodpeckers. Maybe because we don’t really know how avian brain research translates to humans? But science has perfected the art of inducing brain injuries in rats. The proposed lab rat mechanism looked something like this:

Hypothesis: Jugular vein compression will lead to reduced cerebral venous outflow. This will increase intracranial venous volume thereby filling the intracranial space to a greater degree. This will lead to less relative movement or deformation of the brain during impact.

This became part of what researchers described as the intracranial “slosh” hypothesis: the idea that reducing the brain’s ability to move within the cranial vault might reduce traumatic deformation during rapid acceleration and deceleration.

In 2012 researchers placed a collar around the necks of rats that mildly compressed the internal jugular veins before exposing the animals to an impact-acceleration model of mild traumatic brain injury. The intervention increased intracranial and intraocular pressures by approximately 30%. More strikingly, the animals that underwent jugular compression demonstrated dramatically fewer amyloid precursor protein-positive axons—a histological marker of traumatic axonal injury—than animals exposed to the same injury without compression.^¹

That was an intriguing experimental finding. It provided initial evidence that artificially restricting jugular venous outflow could alter the brain’s response to traumatic impact in this rat model. But it did not demonstrate the premise that had helped inspire the experiment:

No one had demonstrated that woodpeckers actually compress their jugular veins during pecking as a neuroprotective mechanism.

That distinction is critical. The experiment provided evidence for an effect of experimentally induced jugular compression in rats. It did not establish jugular compression as a naturally occurring protective adaptation in woodpeckers. Nevertheless, the woodpecker explanation on the surface sounded physiologically plausible, visually compelling, and easy to understand. As the research moved forward, the proposed woodpecker mechanism increasingly became part of the larger story surrounding jugular-compression technology. And eventually, that technology would move from rats to humans.

2016: The Hypothesis Moves Into Humans

Four years after the rat study, researchers published a prospective randomized controlled trial involving adolescent male hockey players. The athletes were divided into a group wearing a collar designed to produce mild bilateral jugular compression and a control group that did not wear the collar during the competitive season.

Helmet sensors recorded head impacts, while researchers used diffusion tensor imaging (DTI) and electrophysiological measurements to evaluate changes over the season. The authors reported group differences in longitudinal neuroimaging and electrophysiological measures and concluded that mild jugular compression may have reduced alterations in white-matter response to repetitive head impacts.²

This was an interesting translational step:

Avian anatomy hypothesis → rodent research → physiological intervention → human sports study

But again, we need to be precise about what had—and had not—been demonstrated. The study did not establish that the collar prevented concussion. It identified differences in surrogate measures, including DTI-derived measures of white-matter microstructure. That distinction between a biomarker change and a clinically meaningful reduction in brain injury is important. Much of the data in the series of pilot studies and clinical trials would also later be called into question.

2016: Meanwhile, Researchers Were Studying the Woodpecker's Actual Tongue

At approximately the same time, another research group was asking a related but different question. Rather than investigating jugular compression, Jung and colleagues directly examined the actual tongue and hyoid apparatus of the woodpecker. The reality is that, while the woodpecker does have a long tongue, the tongue itself does not wrap around its head. In woodpeckers, portions of the hyoid apparatus are greatly elongated and extend around the posterior skull, with the epibranchial elements in some species continuing toward the supraorbital region.

The researchers used micro-computed tomography, electron microscopy, and mechanical testing to characterize the hyoid apparatus. They identified several interesting properties. Cross-sections of the hyoid bones contained relatively stiff internal regions surrounded by more compliant material, while portions of the posterior hyoid demonstrated substantial flexibility. The authors proposed that these properties could provide potential routes for energy absorption or dissipation during pecking.³

The 2016 study identified structural characteristics that plausibly could participate in dissipating energy, but this is not the same thing as demonstrating that this structure is the primary reason the woodpecker avoids brain injury.

It also - a little too quietly - disproved the much stronger popular claim that: The woodpecker's tongue wraps around its brain and acts as a seat belt that prevents concussion.

The tongue doesn't literally wrap around the brain. The elongated hyoid apparatus extends around portions of the skull. These distinctions sound subtle. They aren't. They are exactly where scientific hypotheses become scientific folklore.

Two Woodpecker Stories Were Now Circulating

By this point, two related ideas had become associated with the woodpecker. One involved mechanical energy absorption: The Hyoid/tongue apparatus absorbs or redistributes impact forces and protects the brain. The other involved intracranial fluid dynamics: Jugular compression by the long tongue wrapping around the head leads to increased intracranial blood volume and reduced brain “slosh” thereby protecting the brain from possible concussive forces.

Both attempted to answer the same fascinating biological question:

How does a woodpecker repeatedly strike its head against a tree without suffering the consequences we would expect in a human?

Both stories were intriguing. Both inspired research. But they were not the same hypothesis, and the evidence supporting one did not automatically establish the other. That distinction became blurred in many popular explanations.

2021: The Jugular-Compression Concept Becomes a Medical Device

The human research continued, including studies involving football players and other athletes. Eventually, the concept became the Q-Collar, a C-shaped device designed to apply compressive force over the internal jugular veins during athletic activity.

In February 2021, the FDA granted the Q-Collar De Novo authorization as a Class II medical device. The FDA describes the device category as an “external compression device for internal jugular vein compression.”⁴

This is another place where language matters enormously. FDA authorization did not mean: “The Q-Collar has been proven to prevent concussion.” The FDA's review concerned its use as an aid in protecting the brain from effects associated with repetitive sub-concussive head impacts. The agency's documentation and subsequent statements have specifically cautioned that the evidence does not demonstrate prevention of concussion or serious brain injury.

That is a much narrower claim. And it illustrates another recurring problem in science communication: A statistically significant imaging finding, an FDA-authorized indication, and the prevention of brain injuries are three very different things. However, as word spreads these days, these can become remarkably similar after several rounds of retelling.

2022: A Shock-Absorbing Hammer isn’t a Good Hammer

Then came a study that forced researchers to reconsider a fundamental assumption. Van Wassenbergh and colleagues published an in-vivo biomechanical analysis in Current Biology in 2022. They used high-speed video to analyze pecking in three woodpecker species and measured deceleration at different locations along the head. The logic was wonderfully straightforward.If the woodpecker's cranial structures function as a shock absorber, then the skull should experience less deceleration than the beak.

But that isn't what they found. The researchers found that the woodpecker's head behaved remarkably stiffly during impact. Shock deceleration at the braincase was not substantially reduced relative to the beak.⁵ That led to an important reinterpretation:

A woodpecker's head may be better understood as a highly effective hammer than as a shock absorber.

From an evolutionary perspective, that actually makes considerable sense. A woodpecker is trying to transfer mechanical energy into wood. If its head absorbed a large percentage of that energy before it reached the tree, the bird would have to work harder to accomplish the same task. In other words: A shock-absorbing hammer isn't necessarily a very good hammer.

The researchers' modeling suggested that the woodpecker's relatively small brain and cranial geometry may allow it to experience these extraordinary accelerations while remaining below estimated concussion thresholds derived from primates.⁵

This didn't prove that every previously proposed protective adaptation was irrelevant. It challenged something broader: the assumption that woodpecker cranial anatomy must primarily function by absorbing shock. That is a major conceptual change.

2025: The Game of “Telephone” - Backwards

In 2025, James Smoliga and Mu Yang published an investigative essay in The BMJ examining the scientific history and evidence surrounding the Q-Collar. Their critique went well beyond the woodpecker hypothesis and raised concerns about aspects of the human evidence base, interpretation of imaging biomarkers, study methodology, data reporting, and how the device had been marketed. Those issues and serious allegations deserve evaluation on their own merits.⁶

But one part of their investigation is particularly fascinating. They traced the woodpecker origin story. The idea that woodpeckers protect themselves through jugular compression had become remarkably influential. It appeared in media stories and explanations surrounding the development of the collar. Yet, according to the BMJ reconstruction, the proposed jugular-compression mechanism had not ever been demonstrated in woodpeckers.

Think about that for a moment. A hypothesis inspired by a bird with a long tongue helped motivate:

animal experiments
human experiments
sports research
medical-device development
FDA authorization

While the original proposed mechanism in the inspirational tree-pounding winged marvel itself remained unproven. That is an extraordinary scientific story. But I don't think the correct response is ridicule. I think the correct response is epistemic humility.

How a Hypothesis Quietly Becomes a Fact

I suspect this process happens more often than we recognize.

A researcher writes: “We hypothesize that…”

Another paper describes: “A proposed mechanism…”

A conference presenter explains: “Researchers believe…”

A textbook simplifies the diagram.

A journalist needs a headline.

A social-media graphic removes the qualifier.

Eventually we arrive at:

“Did you know a woodpecker's tongue wraps around its brain so it doesn't get concussions?”

Now a hypothesis has become a fact. At least culturally. Every step may seem reasonable. But notice what disappeared along the way: uncertainty.

The hypothesis didn't necessarily change. Its perceived scientific status did. And that is something all of us who teach science—including me—need to think about.

How Often are We Teaching the Wrong Mechanism?

This may be the most important lesson I take from this entire story. In medicine and neuroscience, we sometimes discover an intervention that produces an effect before we correctly understand why it produces that effect. Later, the mechanism changes. Sometimes slightly. Sometimes completely. The original observation doesn't necessarily disappear.

Suppose, for the sake of argument, future rigorous human studies eventually demonstrate that mild jugular compression produces some clinically meaningful protective effect during repetitive head impacts. That finding would not require woodpeckers to use jugular compression themselves. The human intervention would have to stand on its own physiology and evidence.

Conversely, the fact that an intervention was inspired by nature does not prove that it works in humans. These are separate propositions:

Does the woodpecker use this mechanism? And: Does inducing this physiological state in a human produce a beneficial effect?

One can ultimately be false while the other is true. That's why challenging the woodpecker origin story does not, by itself, settle the question of whether jugular compression affects human brain biomechanics.

But it does mean we should stop using the woodpecker as evidence that it does.

Three Questions We Should Ask When Teaching a Mechanism

Perhaps one way to protect ourselves from this problem is to ask what type of claim we're actually making.

Hypothesis: What explanation is plausible but remains incompletely tested?
Observation: What have we directly demonstrated?
Supported Mechanism: What explanation is supported by converging experimental evidence?

There is nothing wrong with teaching all three. In fact, some of the most interesting ideas in neuroscience belong in the hypothesis category. The problem comes when we teach category one using the language of category three.

And This Isn't Just About Woodpeckers

Neuroscience may be particularly vulnerable to this problem because mechanistic explanations are so useful for organizing extraordinarily complex physiology. We learn a mechanism, it makes sense, and it becomes embedded in both our teaching and clinical reasoning. Then better imaging, electrophysiology, molecular techniques, anatomical tracing, computational modeling, or experimental design reveals another layer of complexity. Sometimes the old model was simply wrong. More often, I find that it was incomplete. Biological systems rarely respect the clean boxes we use to teach them.

The clean linear pathway becomes a network.

The single responsible structure becomes one contributor among several.

The antagonistic systems turn out to cooperate under certain conditions.

The structure we thought caused an effect turns out merely to correlate with it.

The intervention still works—but perhaps not for the reason we thought it did.

That can be frustrating. But it is also exactly what we should expect from a maturing science.

Science Isn't Weakened When the Story Changes

When I heard the woodpecker/jugular-compression explanation presented at a neuroscience conference years ago, I had every reason to take it seriously. It was rooted in published research. It was physiologically plausible. It had generated experimental findings. And one of the principal investigators in the human clinical trials was standing on stage speaking about it.

The appropriate lesson now isn't that we should distrust researchers or stop proposing mechanisms until we can prove every step. Science can't progress that way. We need people willing to observe something unusual, propose an explanation, and design an experiment that might prove them wrong. The lesson is subtler. We need to preserve the distinction between:

What we observed, what we think explains it, and what we have actually demonstrated.

And those of us who teach have an additional responsibility. When the evidence changes, our lectures should change with it. There should be no embarrassment in saying:

“This is what we used to think. Here is why we thought it. Here is what the newer evidence shows. And here is what we still don't know.”

That may actually be one of the most scientific things we can teach. Because the goal of science was never to create explanations that could never change. The goal is to build models that explain the evidence we have—and then be willing to revise those models when better evidence arrives. Sometimes the outcome we observed remains real while the mechanism underneath it changes.

Sometimes an elegant explanation survives. Sometimes it doesn't. And sometimes it takes a woodpecker to remind us of the difference.

References & Suggested Reading

Back to blog