Was T. rex Smarter Than A Baboon?

There are few questions that fascinate us as much as the behavior of these now-extinct giant creatures

People think that the greatest thing that can happen to a paleontologist is to find a rare fossil that helps us understand evolution in a unique way. And well, don’t get me wrong—we LOVE that, especially because this degree of uniqueness isn’t so common anymore. But no, there is something we like even better: coming up with a credible theory of an extinct creature’s behavior. Double points if it is something as charismatic as a Tyrannosaurus rex.

Imagine that we could travel back to the Mesozoic era, navigating a world where dinosaur roaring fills the air. Among the gigantic creatures, the T. rex stands as one of the most terrifying terrestrial predators of all time. I bet that any paleontologist (or enthusiast) who’d be put in this situation would be eager to answer these questions: how smart was T. rex? Were they social? Well, recent scientific research brings some fascinating insights into the cognitive world of dinosaurs, particularly the T. rex.

In 2023, Suzana Herculano-Houzel, a neuroscientist at Vanderbilt University, shook the paleontological community with a groundbreaking claim. Published in the Journal of Comparative Neurology, her research suggested that theropod dinosaurs like the T. rex might have been as intelligent as baboons, equipped with a high number of neurons that could potentially support complex behaviors such as tool use.

However, not everyone was convinced. Scientists don’t just say that they don’t buy something right away. They first perform the necessary tests and then come up with counter ideas. Hence, an international team of paleontologists, neuroanatomists, and cognitive psychologists felt the theory needed some serious straightening. This group, led by Dr. Caspar from the University of Düsseldorf, embarked on a mission to empirically reassess the claims about T. rex’s brainpower.

Their findings, published in The Anatomical Record, take us on a multi-discipline study of the anatomy and capabilities of the T. rex brain. The team revisited the methods used to estimate the dinosaur’s neuron counts and brain size. They found several critical flaws in the previous assumptions and methodologies, which led to the overestimation of T. rex’s cognitive abilities.

Unlike the depiction by Herculano-Houzel, the team’s research suggests that T. rex and its theropod cousins were more on par with modern reptiles like crocodiles and alligators in terms of intelligence, not primates. Doug Wylie, a neurobiologist coauthor in the research from the University of Alberta, explained that dinosaur brains, much like those of other reptiles, don’t fully fill up the skull cavity and are packed more loosely with neurons compared to mammal and bird brains.

This study, though, wasn’t just about debunking a myth; it’s about understanding the biological constraints that shaped the lives of theropod dinosaurs. Herculano-Houzel’s claim came from the fact that theropod dinosaurs had similar neuron density to some primates. However, the new team suggests that this could be a matter of different sizes. For instance, an adult male baboon, who is highly intelligent by non-human standards, weighs between 14 and 40 kilograms and sports a brain bustling with neurons. In contrast, a T. rex, which could weigh about 7 tons, could have required a similar neuron density not because of its enhanced cognitive abilities, but to manage its enormous body and basic survival functions—leaving little room for the complex cognitive functions suggested by the earlier study.

That is, to achieve these cognitive abilities, they would require either a bigger brain or a different brain architecture more densely packed with neurons. This is because the correlation between neuron density and cognitive capabilities is significant in determining an animal’s intellectual capacity.

But you may ask, why does this matter? Well, the way we think about dinosaur brains affects more than just the plot of the next Jurassic Park movie. It influences our understanding of how intelligence has evolved across different groups of animals and helps scientists piece together the ecological networks in fossil ecosystems.

Moreover, this research underscores the importance of interdisciplinary collaboration in science. Combining the expertise of paleontologists who know the ins and outs of dinosaur anatomy with neurobiologists skilled in brain physiology and cognitive psychologists who understand behavior leads to more robust and reliable science. As Wylie points out, the project was a mammoth task, requiring coordination and cooperation across fields to challenge established ideas effectively.

In essence, while the idea of a T. rex crafting tools and passing down cultural traditions might be something that we want to entertain for the next Dinosaur Train episode, the reality supported by current scientific evidence paints a different picture. Therapod dinosaurs were certainly successful in their ecological niches, dominating the landscape for millions of years, but their success was unlikely due to their exceptional cognitive abilities.

Even more, what this discussion highlights is the dynamic and accountable nature of scientific research — ideas are constantly questioned, tested, debated, and revised. Further, as new tools and technologies emerge, our understanding of the fossil record will continue to evolve. So, the next time you have the opportunity to admire a T. rex in a museum, consider not just its fearsome teeth and powerful legs, but also the ongoing journey to uncover the secrets locked within its fossilized bones (and depositional environment). This isn’t just about dinosaurs; it’s about exploring the very limits of what we can learn from the remnants of a world long gone.