When someone near you looks at something in the surroundings, you tend to instinctively look in the same direction. This behavior is observed in mammals, birds, and even reptiles. It’s a useful way to gather information about what has caught the attention of others, which you might have missed otherwise. However, a more advanced behavior is to follow someone’s gaze even when the object they are looking at is initially hidden from your view. By moving yourself to a position where you can see what the other person sees, you demonstrate an understanding that they have a different perspective. This ability is called visual perspective taking and develops in children between the ages of one-and-a-half to two years. It lays the groundwork for understanding referential communication and recognizing that others have thoughts and perspectives that may differ from your own.
Visual perspective taking has been observed in only a few species so far, including apes, some monkeys, dogs, and crows. However, the evolutionary origins of this important social skill are not well understood. To shed light on this topic, a team of researchers from Lund University conducted a study to investigate the potential early emergence of visual perspective taking in dinosaurs. They compared alligators with the most primitive living birds called palaeognaths. The researchers discovered that visual perspective taking likely originated in the dinosaur lineage, possibly as early as 60 million years ago or even earlier, predating its appearance in mammals. This suggests that this ability was present in dinosaurs long before it evolved in other groups of animals.
Crocodilians, which include crocodiles and alligators, are the closest living relatives to birds. Their neuroanatomy has remained mostly unchanged for hundreds of millions of years and is similar to the common ancestor of dinosaurs and crocodilians. Palaeognath birds, such as ostriches, emus, rheas, and flighted tinamous, share similarities in brain structure with their dinosaur ancestors, particularly the non-avian paravian dinosaurs, which include famous species like velociraptors. By comparing these two groups of animals, researchers can gain insights into the evolutionary lineage of dinosaurs that eventually led to the development of modern birds. It helps create a framework to understand the extinct lineage of dinosaurs leading up to present-day avian species.
The study found that alligators do not exhibit visual perspective taking, although they do follow the gaze of others to a location that is visible. On the other hand, all tested bird species showed evidence of visual perspective taking. Additionally, the birds demonstrated a behavior called “checking back,” where the observer looks back into the eyes of the individual whose gaze they followed. If they couldn’t find anything in the initial direction of the gaze, they would re-track the gaze to ensure they didn’t miss anything. This behavior indicates an expectation that the gaze is referring to something specific in the environment. Previously, this behavior had only been observed in humans, apes, monkeys, and ravens, so the findings highlight the remarkable cognitive abilities of birds in understanding the intentions and perspectives of others.
The emergence of palaeognath birds, which occurred 110 million years ago, predates the development of visual perspective taking in two mammalian groups: primates and dogs, by approximately 60 million years. Considering the similarities in neuroanatomy between these birds and their non-avian dinosaur ancestors, it is plausible that this skill originated even earlier in the dinosaur lineage. However, it is less likely to have been present in the earliest dinosaurs, as their brains were more similar to those of alligators. Future research may reveal that visual perspective taking is more widespread among mammals than currently known, but even in that case, it would likely still be preceded by its origin in dinosaurs. Interestingly, the emergence of visual perspective taking in dinosaurs, including birds, aligns with their superior visual capabilities compared to many mammals that historically adapted for nocturnal activities. It was only with the evolution of primates and certain carnivorous mammals that our visual abilities improved.
Indeed, this finding challenges the prevailing view that mammals were the primary drivers of complex cognition and suggests that they may not be the sole standard for comparing cognitive abilities in animals. The growing body of research on avian dinosaurs, specifically birds, highlights their remarkable neurocognitive capacities. This raises the possibility of reevaluating our understanding of the evolutionary history of cognition. It prompts us to consider that avian dinosaurs, with their unique cognitive abilities, may have played a significant role in shaping the natural history of cognitive development. This shift in perspective encourages a broader exploration of cognitive capabilities across different animal groups and the recognition of the diverse pathways to complex cognition in the animal kingdom.
Comments from the authors:
Senior author, prof. Mathias Osvath:
“Early in my career, crow birds earned the nickname “feathered apes”, due to numerous research findings that showcased their remarkable cognition. However, I’m beginning to question whether it would be more fitting to consider primates as honorary birds.”
First author (then PhD-student), Dr Claudia Zeiträg:
“Birds are commonly being overlooked when it comes to their cognitive skills. Our findings show that they do not only have several cognitive skills on par with those of apes, but that their forebearers most likely had these skills long before they evolved in mammals.”
Middle author, Dr Stephan Reber:
“Crocodilians are ideal models to study the evolutionary origins of cognitive capacities in birds. What they share most probably existed in the common ancestor of dinosaurs and crocodilians. If crocodilians lack an ability birds possess, it likely evolved in the dinosaur lineage after the split. This approach allows us to study the cognition of extinct species.”
