The study of intelligence is an extremely difficult task, even in animals living today. In part, this is because much of the scientific jury is still out on what intelligence even is.
So estimating the intelligence of any now-extinct creature is a particularly difficult task. In the case of the dinosaurs, combine the fact that they have been extinct for tens of millions of years, and this task requires… even more brains and speculation.
However, scientists have pursued several different methods to address the question of dino intelligence.
Their approaches rely on a combination of morphological proxies for intelligence such as absolute and relative brain size and number of neurons, or mapping dinosaurs against their relatives on the evolutionary tree.
As an added challenge, the term dinosaur itself is a broad category. These creatures were distinguished by great diversity their morphologylifestyles and diets, meaning that some dinosaurs were probably much smarter than others.
Suffice to say, the debate is rife and the research methods mind-boggling.
How smart were the dinosaurs?
In the 1970s, when scientists first wondered if there was information to be gleaned about a dino’s intelligence from morphological traits—such as how big the brain was—they developed the EQ, because encephalization coefficient.
This calculation measures the weight of an animal’s brain compared to the size of the rest of its body, then contrasts that figure with other animals within its taxonomic group.
Humans, with their massive brains compared to their relatively small bodies, have an EQ of approximately 7.5.
The Dolphins are somewhere between 4.0 and 4.5. And chimpanzees land between 2.2 and 2.5.
Measuring the size of a dinosaur’s brain
As for the dino family, T-Rex it falls between 2.0 and 2.4 compared to other reptiles.
That’s probably what it means T. rex they may have been as smart as chimpanzees, according to the book The rise and fall of the dinosaurs by paleontologist Steve Brusat.
This seems to suggest that T. rex he wasn’t dumb at all.
Read more: Tyrannosaurus Rex: Scary. Smart. Social?
Encephalization coefficient methods
But while the encephalization ratio has been a great starting tool for scientists in recent decades, there is tension among scientists about how much it can actually be trusted.
“These animals were incredibly large, so I think you’re getting a pretty skewed view of what brain size means to the animal,” says Scott Rogers, a professor of neurobiology at the University of Utah. who also used brain morphology to learn more about dinosaur behavior.
One important consideration is that Brusatte’s calculation of T. rex brain is based on comparing it to modern reptiles, resulting in a high EQ number. If you compare it to birds instead, it’s actually extremely low, 0.1-0.2, according to a 2013 study.
Therefore, EQ comparisons between major groups of animals may not be as meaningful.
Brain mass revisited
On the other hand, brain mass is notoriously difficult to calculate.
Brusatte’s calculations suggest that 50 percent of an adult’s brain cavity T. rex was performed by the brain. But modern crocodiles fill only 30 percent of the space above their heads.
Also, when tested on living animals today, brain size does not match their cognitive abilities very well.
So, comparing T. rex intelligence to chimpanzee intelligence would be very misleading.
Read more: The human brain has been getting smaller since the stone age
Were dinosaurs intelligent?
In January of this year, a scientific article in Journal of Comparative Neurology claim that some dinos are much smarter than previously thought.
Tyrannosaurs and velociraptors can be called the “primates of their time,” Susanna Herculano-Housel, a neuroscientist at Vanderbilt University who authored the study said the Washington Post.
This is based in part on findings that they have approximately 3 billion cerebral neurons in a brain weighing 343 grams, more than baboons.
That would mean T. rex he didn’t look like the idiot we’d long thought him to be.
More, Kai Robert Caspar, a comparative cognition researcher at the Heinrich-Heine University in Düsseldorf, and many of his colleagues questioned these results. They are working on a research paper to debunk these findings.
Challenging neural theory
First, Kaspar says, there are errors in the article’s methods: Once again, it assumes T. rexThe brain of has filled the entire cranial cavity. It also suggests a neuronal density similar to that of some birds, which is not necessarily the case in the brain of T. rex.
Second, just like EQ, it may be inaccurate to make assumptions about intelligence based on quantity rather than quality.
“I’m quite skeptical about whether we should accept the number of neurons as a good proxy for cognitive ability,” Kaspar says. “The neuron can be the computational unit of the nervous system … it also matters how the neurons are interconnected and organized.”
Considering the living relatives of the dinosaurs
Let’s not forget that some animals alive today are distant relatives of dinosaurs.
These include birds that evolved from carnivorous dinosaurs called theropods (and including T. rex ) and crocodiles, which evolved from a dinosaur ancestor, the archosaurs (also known as ruling reptiles), also related to T. rex.
On the evolutionary tree, these animals sit on either side of the dinosaurs, so scientists can make comparisons and make educated guesses about what characteristics and traits from these creatures today were also present in the dinosaurs back then.
This technique is called phylogenetic bracketing.
“If you have a certain cognitive trait, if it’s present in both crocodilians and birds, then I think we can make an argument that it was present in dinosaurs as well,” Caspar says.
Read more: What species today are descendants of dinosaurs?
Compared to birds and crocodiles
According to this theory, scientists say that some dinosaurs were probably as smart as birds, and others were as smart as crocodiles.
But phylogenetic brackets don’t let you predict things like that, Kaspar says, because you have to take into account other lines of evidence.
For example, the morphology of the brain of T. rex is more similar to crocodiles than to birds, although it is more closely related to the latter. And this factor is much more indicative than evaluating a trait based on its presence or absence in living relatives.
Sizing of brain casts
Rogers of the University of Utah specializes in the use of internal measurements from dinosaur skulls — also known as “endocasts” — and compared them to brain models of their living relatives.
For example, when you take the Allosaurus brain cast (quite similar to T. rex ) and by placing it next to the model of what an alligator brain looks like, it becomes clear that they have very similar shapes.
“Bingo,” Rogers says, holding the two together. “Super good match.”
This, he says, is the most accurate “first evidence” of Allosaurus behavior, or T. rex they also showed how their brains work. This is because the method can reveal where the neurons were concentrated and compare it to the function of different areas of the brain in animals alive today.
Neural models like crocodiles
“[Like crocodiles,] the neurons were concentrated down here in the sensory part, the olfactory part. Not quite up where you’d expect the telencephalon to be,” Rogers says.
The latter region is much more developed in birds and mammals and is responsible for sensory processing and learning.
This now means that we can make rough assumptions that T. rex it was probably smart in the same way that crocodiles and alligators are smart.
“That’s the kind of comparison I find useful,” Rogers says. “Can we say it’s accurate? Well, of course not.”
Read more: These 7 new dinosaur species were discovered in 2022
The best IQ test
Moving forward, it’s imperative that scientists take an “integrative approach,” according to Caspar.
This means relying on as many different lines of evidence as possible, from neuron counts to endoskeletons to making comparisons with living animals.
After all, we just don’t know how smart dinosaurs could have been, according to Caspar.
Rogers adds that looking at context can provide some answers: “Intelligence is really more of an idea of adaptability. I mean, how successful are you in your environment?’
From his point of view, the dinosaurs were around for tens of millions of years and did “extremely well.”
“It took a pretty significant change in the environment to wipe them out,” he says. “To me, that suggests they were actually quite intelligent.”
Read more: What killed the dinosaurs?