Woodpeckers experience forces up to 1,200-1,400 g while pecking. It is assumed due to evolutionary adaptations, the woodpecker is immune to brain injury. This assumption has led to the use of the woodpecker as a model in the development of sports safety equipment such as football helmets. However, a new study from the Boston University School of Medicine complicates this story by showing that woodpecker brains contain build-ups of the tau protein, a protein associated with brain damage in humans.
The downy woodpecker (Dryobates pubescens). Image credit: Wolfgang Wander.
“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,” said Dr. Peter Cummings, lead author on the study.
“The weird thing is, nobody’s ever looked at a woodpecker brain to see if there is any damage.”
To find the answer to this question, Dr. Cummings and colleagues examined bird brains — downy woodpeckers (Dryobates pubescens) for the experimental data and non-head-injury-prone red-winged blackbirds (Agelaius phoeniceus) as a control — for accumulation of the tau protein.
“The basic cells of the brain are neurons, which are the cell bodies, and axons, which are like telephone lines that communicate between the neurons,” said co-author Dr. George Farah.
“The tau protein wraps around the telephone lines — it gives them protection and stability while still letting them remain flexible.”
“In moderation, tau proteins can be helpful in stabilizing brain cells, but too much tau build-up can disrupt communication from one neuron to another.”
“When the brain is damaged, tau collects and disrupts nerve function — cognitive, emotional, and motor function can be compromised.”
According to the team, the woodpeckers’ brains had far more tau protein accumulation than the blackbirds’ brains.
However, while excessive tau buildup can be a sign of brain damage in humans, this might not be the case for woodpeckers.
“We can’t say that these woodpeckers definitely sustained brain injuries, but there is extra tau present in the woodpecker brains, which previous research has discovered is indicative of brain injury,” Dr. Farah said.
“The earliest woodpeckers date back 25 million years — these birds have been around for a long time,” Dr. Cummings said.
“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.”
“So, woodpeckers show signs of what looks like brain damage in humans, but it might not be a bad thing.”
The findings appear in the journal PLoS ONE.
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G. Farah et al. 2018. Tau accumulations in the brains of woodpeckers. PLoS ONE 13 (2): e0191526; doi: 10.1371/journal.pone.0191526
