Bird Brains: Size Doesn't Matter But Number of Neurons Does

New research shows avian intelligence is based on neurons in the telencephalon

Posted Jul 16, 2016

Birds are smart. A large empirical database on their cognitive capacities supports this claim, and readers of Psychology Today can learn more about this topic from the excellent essays posted under Avian Einsteins by John Marzluff and Tony Angell (please also see "Bird Minds: An Outstanding Book About Australian Natives").

A question of interest to many researchers centers on the neural bases of avian intelligence. Bird brains can be pretty small and many have assumed this would mean they couldn't process information as well as larger brained animals. I wrote about this topic in an essay called "The Birds and the Bees and Their Brains: Size Doesn't Matter" in which I noted, "Big brains and high EQ's [encephalization quotients] may be useful for those animals who need them to be card-carrying members of their species, but small-brained animals do very well as long as they can do what they need to do to survive and thrive in their own worlds. The notion that small-brained animals are 'less intelligent' than big-brained animals and 'suffer less' also needs to be revisited as it's surely a myth." (For more on this topic please also see "Animals as Persons: Can We Scale Intelligence or Sentience?")

Along these lines, in an essay called "Does Brain Size Matter?" Psychology Today writer Frederick Coolidge similarly wrote, "We have established that brain size alone doesn’t predict intelligence in modern folk, and it probably didn’t predict intelligence in our cousins, the Neandertals, and Homo sapiens living at that same time."

If size doesn't matter, what does?

If brain size, in and of itself, is not related to intelligence, what is? A recent essay published in the Proceedings of the National Academy of Sciences by Seweryn Olkowicz and his colleagues called "Birds have primate-like numbers of neurons in the forebrain" seems to have answered this question (popular accounts of this research can be read here). Their paper is available online and the authors summarize their landmark findings succinctly as follows. They summarize the significance of their research as follows: 

Birds are remarkably intelligent, although their brains are small. Corvids and some parrots are capable of cognitive feats comparable to those of great apes. How do birds achieve impressive cognitive prowess with walnut-sized brains? We investigated the cellular composition of the brains of 28 avian species, uncovering a straightforward solution to the puzzle: brains of songbirds and parrots contain very large numbers of neurons, at neuronal densities considerably exceeding those found in mammals. Because these “extra” neurons are predominantly located in the forebrain, large parrots and corvids have the same or greater forebrain neuron counts as monkeys with much larger brains. Avian brains thus have the potential to provide much higher “cognitive power” per unit mass than do mammalian brains.

Their abstract reads:

Some birds achieve primate-like levels of cognition, even though their brains tend to be much smaller in absolute size. This poses a fundamental problem in comparative and computational neuroscience, because small brains are expected to have a lower information-processing capacity. Using the isotropic fractionator to determine numbers of neurons in specific brain regions, here we show that the brains of parrots and songbirds contain on average twice as many neurons as primate brains of the same mass, indicating that avian brains have higher neuron packing densities than mammalian brains. Additionally, corvids and parrots have much higher proportions of brain neurons located in the pallial telencephalon compared with primates or other mammals and birds. Thus, large-brained parrots and corvids have forebrain neuron counts equal to or greater than primates with much larger brains. We suggest that the large numbers of neurons concentrated in high densities in the telencephalon substantially contribute to the neural basis of avian intelligence.

Being called a "birdbrain" can be a most-welcomed compliment 

This research makes a significant contribution to comparative studies of animal cognition and shows that being called a "birdbrain" can be a most-welcomed compliment deserving of a "thank you very much," and that we need to keep the door open to "surprises" stemming from research on the cognitive and emotional lives of other animals. There really is so much to learn and just when we think we know it all ...

Marc Bekoff's latest books are Jasper's Story: Saving Moon Bears (with Jill Robinson), Ignoring Nature No More: The Case for Compassionate Conservation, Why Dogs Hump and Bees Get Depressed: The Fascinating Science of Animal Intelligence, Emotions, Friendship, and Conservation, Rewilding Our Hearts: Building Pathways of Compassion and Coexistence, and The Jane Effect: Celebrating Jane Goodall (edited with Dale Peterson). The Animals' Agenda: Freedom, Compassion, and Coexistence in the Human Age (with Jessica Pierce) will be published in early 2017. (Homepage: marcbekoff.com; @MarcBekoff)

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