It’s challenging to decipher what birds might be ‘thinking’ while flying, but researchers in Australia and Canada are uncovering fascinating insights by examining the interiors of birds’ skulls.
It’s challenging to decipher what birds might be ‘thinking’ while flying, but researchers in Australia and Canada are uncovering fascinating insights by examining the interiors of birds’ skulls.
A collaborative effort between evolutionary biologists at Flinders University in South Australia and neuroscience experts at the University of Lethbridge in Canada has led to an innovative method for reconstructing both extinct and living birds’ brain structures. This has been achieved by creating digital ‘endocasts’ from the vacant cranial spaces of bird skeletons.
In a study published today in Biology Letters, researchers from the ‘Bones and Diversity Lab’ at Flinders and the Iwaniuk Lab at the University of Lethbridge revealed that even dry museum specimens of long-gone birds can provide intricate details about their brain structure, including metrics of the main centers linked to intelligence and agility.
This groundbreaking discovery stemmed from a comparison of historical microscopic brain samples with digital impressions of the inner braincase of birds, constituting the most extensive study of its kind with data on 136 species.
“We found a remarkable correlation between the two, which means we don’t need to examine the actual brain to understand the proportions within a bird’s brain,” stated Aubrey Keirnan, the study’s lead author and PhD candidate at Flinders University.
“The term ‘bird brain’ is often used pejoratively, but birds actually have large brains, almost making their braincase appear as their main feature, apart from their beaks. We wanted to investigate whether the skull’s imprint of the brain accurately reflects the proportions of two vital areas of the actual brain.”
The team, alongside colleagues from the Department of Neuroscience at the University of Lethbridge, used scans of the skulls of 136 bird species for which they also had microscopic brain analyses or literature references.
This enabled them to verify if the volumes of the forebrain and the cerebellum matched the surface areas of the endocasts.
Researchers were surprised by the remarkably close alignment between the actual brain volumes and the digital replicas.
“We employed computed microtomography to scan the bird skulls, which allowed us to digitally reconstruct the brain cavity to visualize the brain’s imprint, known as an endocast,” explained Associate Professor Vera Weisbecker, a senior co-author from Flinders University’s College of Science and Engineering.
“The correspondence was nearly 1:1, which we didn’t anticipate. However, this is fantastic news as it lets us explore the neuroanatomy of elusive, rare, and even extinct species without needing to access their actual brains.”
Associate Professor Weisbecker emphasized how advanced digital technologies are unlocking solutions to some long-standing mysteries in animal diversity.
“The advantage of digital endocasts is their non-destructive nature. Previously, researchers had to introduce liquid latex into a brain case, wait for it to solidify, and then destroy the skull to obtain the endocast.”
“Now, with non-destructive scanning, we can create endocasts even from the rarest birds and generate digital archives of skulls and endocasts to share with other scientists and the public.”
Having significant experience in avian brain research, University of Lethbridge Professor Andrew Iwaniuk, who co-led the study with Associate Professor Weisbecker, did not foresee such a strong relationship between the brain tissue and the endocasts.
“Most of the outer forebrain appears on the skull surface, but a significant part of the cerebellum is hidden in this area. Additionally, avian cerebella contain ‘folds’ that can be obstructed by a large blood vessel known as the occipital sinus,” remarked Professor Iwaniuk.
“Considering that the degree of obscurity can differ by species, I didn’t expect a robust correlation between the endocast surface area and the brain volume across all the examined species.”
He further noted that this research reinforces existing findings from other studies, which include critically endangered modern birds and potentially even species that have gone extinct.
However, the team cautions that it remains unclear how applicable their data will be to dinosaurs, which are the closest extinct relatives of birds.
“For instance, crocodiles are currently the nearest living kin to birds, yet their brains are vastly different from those of birds and don’t fit within the braincase adequately to yield informative data,” added Keirnan.
