Woodpeckers drill into trees to get lunch — a meal of insects that live inside the wood. The birds also peck to make holes deep enough for nesting. And when the birds peck, they peck hard. Very hard. They hammer their beaks into those trees so hard that their brains may get banged up. That’s the finding of a new study.
The study turned up a protein in the birds’ brains that in people would suggest the presence of brain damage.
This is surprising. A woodpecker’s brain experiences a force 14 times greater than what would cause a concussion in a human. A concussion is caused by a severe blow to the head. Scientists had long assumed woodpeckers are not harmed by that pecking. In fact, some sporting-goods companies have modeled their helmets after woodpecker skulls.
Severe or repeated concussions can cause brain damage in people. And one sign of that is the buildup in the human brain of a protein called tau. It can accumulate after a concussion. Alzheimer’s disease and other disorders that attack the brain also can lead to a buildup of tau.
While researchers have found tau in plenty of human brains, no one had ever looked for it — or other signs of brain injury — in woodpeckers, says George Farah. He is a biologist who studies the brain. “That’s what science is about,” he says — “questioning everything.”
Farah led the new study while he was a graduate student at Boston University in Massachusetts. His team’s findings appear February 2 in PLOS ONE.
In looking for data, Farah and his team turned to the collections of the Field Museum in Chicago, Ill., and the Harvard Museum of Natural History in Cambridge, Mass. The researchers looked at brains of 10 woodpeckers from five species. They also looked at brains from five red-winged blackbirds. Why blackbirds? Because they don’t peck, blackbirds served as a control (an unaffected comparison group). This let the researchers compare the brains of pecking and non-pecking birds.
All the birds had been preserved in jars of alcohol. The researchers removed the birds' brains and took very thin slices. Each slice was less than a fifth the thickness of a sheet of paper. Farah and his team then stained the slices with a special dye that highlights tau protein.
Next, they looked at the brain tissue under a microscope. The stains turned up a lot tau protein in the woodpecker brains. Blackbird brains showed none.
Farah is careful to say his findings don’t prove that these woodpeckers had brain damage. Instead, they call into question that old assumption that these birds don’t suffer harm.
“Woodpeckers have been around for about 25 million years,” he notes. It doesn’t make sense for the pecking behavior to have lasted that long if the birds were seriously harming their brains with it.
Maybe their brains instead have evolved to handle tau protein, he says. Or perhaps, he says, tau protein might even protect a woodpecker’s brain.
Farah hopes this study leads other scientists to take a closer look at tau protein. “Maybe tau could be somehow useful or protective [of human brains],” he says.
Julian Bailes is a neurosurgeon and brain researcher at NorthShore University HealthSystem Neurological Institute. It’s in Evanston, Ill. A former doctor for the Pittsburgh Steelers football team, he has spoken widely about the risk of concussion among athletes. He agrees that people should be careful in interpreting Farah’s findings.
“Tau is very complex,” Bailes says. “The fact [Farah’s team] found it in the woodpeckers is very interesting. But we don’t even fully understand it in humans.” For instance, tau is not found only in damaged brains. It sometimes shows up in the brains of healthy people.
So it’s still too early to know how, or even if, the woodpecker data will help people. The best advice is still old advice, Bailes notes: When playing a sport where concussion is a risk, wear a helmet.
behavior The way something, often a person or other organism, acts towards others, or conducts itself.
biology The study of living things. The scientists who study them are known as biologists.
concussion Temporary unconsciousness, or headache, dizziness or forgetfulness due to a severe blow to the head.
control A part of an experiment where there is no change from normal conditions. The control is essential to scientific experiments. It shows that any new effect is likely due only to the part of the test that a researcher has altered. For example, if scientists were testing different types of fertilizer in a garden, they would want one section of it to remain unfertilized, as the control. Its area would show how plants in this garden grow under normal conditions. And that gives scientists something against which they can compare their experimental data.
force Some outside influence that can change the motion of a body, hold bodies close to one another, or produce motion or stress in a stationary body.
graduate student Someone working toward an advanced degree by taking classes and performing research. This work is done after the student has already graduated from college (usually with a four-year degree).
insect A type of arthropod that as an adult will have six segmented legs and three body parts: a head, thorax and abdomen. There are hundreds of thousands of insects, which include bees, beetles, flies and moths.
microscope An instrument used to view objects, like bacteria, or the single cells of plants or animals, that are too small to be visible to the unaided eye.
neurological An adjective that refers to the brain, spinal cord or nerves.
protein A compound made from one or more long chains of amino acids. Proteins are an essential part of all living organisms. They form the basis of living cells, muscle and tissues; they also do the work inside of cells. Among the better-known, stand-alone proteins are the hemoglobin (in blood) and the antibodies (also in blood) that attempt to fight infections. Medicines frequently work by latching onto proteins.
risk The chance or mathematical likelihood that some bad thing might happen. For instance, exposure to radiation poses a risk of cancer. Or the hazard — or peril — itself. (For instance: Among cancer risks that the people faced were radiation and drinking water tainted with arsenic.)
skull The skeleton of a person’s or animal’s head.
symptom A physical or mental indicator generally regarded to be characteristic of a disease. Sometimes a single symptom — especially a general one, such as fever or pain — can be a sign of any of many different types of injury or disease.
tau protein A family of proteins that normally stabilize tiny tube-like structures in the axons of neurons — a type of brain cell. In some brain diseases, these proteins may become altered. Now they can form abnormal tangles, which can help kill brain cells.
tissue Made of cells, any of the distinct types of materials that make up animals, plants or fungi. Cells within a tissue work as a unit to perform a particular function in living organisms. Different organs of the human body, for instance, often are made from many different types of tissues.