Since 2016, scientists have known that bird brains have far more neurons than mammal brains of the same size, potentially explaining their levels of intelligence despite their small body size. How birds are able to provide the energy to power these extra neurons has been a bit of mystery.
It turns out that birds might have a more efficient way of processing glucose, meaning that the neurons need about a third less than neurons in a mammalian brain.
German researchers used imaging techniques to estimate the glucose metabolisms in pigeons and combined this with modelling to work out how fast the birds’ brains used glucose and how much they used.
The researchers were surprised to find that even when awake, pigeons used an unexpectedly small amount of glucose to power their numerous neurons – about three times on average less than the same processing in mammalian brains (yes, we humans belong in this category!).
The reasons why or how aren’t clear yet but could be related to the high body temperature in birds or perhaps the specific layout of their brains.
“Our finding explains how birds are able to support such high numbers of neurons without compromising on processing power,” says Kaya von Eugen of the Ruhr University Bochum in Germany and first author of the study.
“In the long parallel evolution of birds and mammals, birds evolved smaller brains with high numbers of neurons capable of advanced cognitive performance. And it seems that the combined effect of bird-distinct elements — small neuron size, high body temperature, and bird-brain-specific layout — might have generated a possible advantage in neuronal processing of information at a higher efficiency: cheap neurons with advanced processing capacity.”
Understanding how bird neurons are able to operate on a smaller energy budget and therefore support more neurons than mammal brains of the same size is a high priority for the researchers.
But, for now, next time you want to call someone a bird brain, you might want to save it for people who are really efficient thinkers.
Clare Kenyon is a science journalist for Cosmos. An ex-high school teacher, she is currently wrangling the death throes of her PhD in astrophysics, has a Masters in astronomy and another in education. Clare also has diplomas in music and criminology and a graduate certificate of leadership and learning.
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