Scientists have looked closely at the brains of various birds and come to an unexpected conclusion, due to the high density of neurons in their brains, they are actually not so ‘simple’ after all.
Bird Brain – No longer an insult?
If someone does something stupid or thoughtless, a typical insult would be ‘you bird-brain’. This was based on the assumption that birds, with their small heads and therefore small brains were not the ‘sharpest tools in the box’.
Well, it appears you may need to think again, and perhaps change your vocabulary, as it may turn out that ‘bird-brain’ is actually a compliment.
Traditional assumptions were based on both actual and relative size of their brains. The human brain makes up 2% of the total body mass, compared with under 1% for most birds. Yet recently there has been evidence that some birds, especially crows and ravens, can recognize themselves in a mirror, use tools and save food. How is this possible?
New study gives fresh insight on birds’ brains
A new study published in the Proceedings of the National Academy has shed some new light on how birds’ brains are composed and how we may have significantly underestimated our feathered friends.
The study dissected the brain of 28 species of bird and counted the number of neurons by coloring them with dye.
For pure numbers, the birds do not fare well. A human brain has over 86 billion neurons, whereas the top ranked bird was the raven with just 2.17 billion. The blackbird has just 0.38 billion neurons.
It’s all relative
But where the data needs further analysis is the the density of these neurons. In general birds brains are crammed full of neurons, with far more neurons per gram than most animals.
This density helps their brains to make more connections, which in turn increases capacity for processing information.
For neurons per gram in the brain, the human is just 57, the raven 154 and the blackbird 201. Birds also have a much higher density than other animals of a comparable size like rats and mice. Humans rank below the emu (brain just 0.7% of body mass) and the squirrel.
Where the neurons are located
As we have all seen on diagrams of the brain, different parts are used for different tasks or things. The brains of birds, especially parrots and larger songbirds tended to have relatively more neurons in the pallium.
The pallium is the layers of grey and white matter that cloak (pallium is actually Latin for cloak) the top of the forebrain. This area of the brain is associated with voluntary actions.
Birds have less neurons in other parts of the brain like the cerebellum which is associated with coordination and regulation of muscle movement.
They also have a smaller number of non-neuronal cells, like glial cells or white matter which are essential for the human ability to acquire and understand knowledge – thinking basically.
Why the difference
No one is yet fully able to understand the differences or why they came out about. It is likely that the birds brain has evolved to give greater control over their week and feet. The high density of neurons allow for greater learning in a smaller brain area.
As the physics of flying dictate that the brain can only be a certain size and weight, they need to maximize all available space and this is why they can still manipulate tools, learn and recognize different mating calls and songs.
