A controversial research suggests that certain dinosaurs may have had intelligence comparable to that of current apes.

 

A controversial research suggests that certain dinosaurs may have had intelligence comparable to that of current apes

Did the Tyrannosaurus rex have the same level of intelligence as a baboon? It is not in the nature of scientists to make comparisons of intellect across other species (everyone is unique, after all), but a recent research that has generated a lot of controversy claims that certain dinosaur brains were as densely packed with neurons as those of contemporary primates. If this is the case, it would indicate that they were very clever, even more so than what scientists had previously believed, and they may have accomplished things that are only possible for exceptionally intelligent creatures and humans, such as utilizing tools.

The results, which were published in the Journal of Comparative Neurology only the previous week, are causing a stir among paleontologists on social media and elsewhere. Others contend that the neuron estimations are inaccurate, which casts doubt on the findings of the research. However, other individuals are praising the work as an excellent first step toward better comprehending the intelligence of dinosaurs.

It has never been a simple task to determine the level of intelligence possessed by dinosaurs. Historically, scientists have used a metric known as the encephalization quotient (EQ), which compares the total volume of an animal's brain to the total volume of its body. Some people believe that since the EQ of a T. rex was around 2.4, but the EQ of a German shepherd dog is 3.1 and the EQ of a person is 7.8, that it must have been at least somewhat intelligent.

However, EQ is not infallible by any means. According to Ashley Morhardt, a paleoneurologist at the Washington University School of Medicine in St. Louis who was not engaged in the study, body size changes separately from brain size in many species. Morhardt was not involved in the research. "EQ is a problematic statistic, particularly in the context of researching extinct animals."

Suzana Herculano-Houzel, a neuroanatomist at Vanderbilt University, was looking for an alternative that was more reliable, so she turned to a different measure: the density of neurons in the cortex. The cortex is a wrinkled outer area of the brain that is essential to most intelligence-related tasks. She had assessed the number of neurons in the brains of a variety of animal species, including humans, in the past by dissolving brains in a detergent solution, which she referred to as "brain soup," and then measuring the number of neurons in various regions of the brain.

Using dinosaur brains would not allow for such to happen. But Herculano-Houzel saw an opportunity when researchers released a vast database demonstrating that, in comparison to reptiles, birds (and mammals) had substantially larger density of neurons in their cortices. This took place the previous year. Herculano-Houzel wanted to find out whether she could use certain comparative anatomy tactics to estimate the neuronal density of dinosaurs since modern birds are connected to extinct theropods, which are a group of predatory dinosaurs that includes T. rex. Theropods are related to modern birds.

She developed an equation that correlates the brain mass of an animal with the approximate number of neurons in the cerebrum, which includes the cortex, by using estimated brain masses obtained with CT scans of dinosaur skulls (see 3D model, below), as well as a large database of brain masses of birds and reptiles from the previous year. The 3D model can be found below. She discovered that the brains of theropod dinosaurs, such as Brachiosaurus, roughly follow the same rules as the brains of modern birds that are warm-blooded, such as ostriches, whereas the brains of sauropod dinosaurs, such as Brachiosaurus, are more similar to those in modern reptiles that are cold-blooded. Depending on the species, ornithischian dinosaurs, another group of dinosaurs that includes Triceratops, and certain pterosaurs followed either the first or the second brain equation. After that, she did some calculations and came up with a number of different estimates for the neuronal densities of a range of different dinosaur species.

According to Herculano-Houzel, "It's great, quite honestly, to be able to acquire these figures for these beautiful species who don't exist any more and to be able to contribute something to the jigsaw of what were their lives like... before the asteroid."

Alioramus, a theropod that was six meters in length and lived in what is now Mongolia around 70 million years ago, had somewhat more than one billion neurons in its brain, making it comparable to capuchin monkeys in this regard. According to Herculano-research, Houzel's the brain of the T. rex contained an estimated 3.3 billion cortical neurons while weighing just a third of a kilogram, making its neuronal density greater than that of baboons.

She quotes herself as saying, "I have a whole newfound respect for T. rex." "Something that massive with those fangs that had the cognitive capabilities, numberwise, of a baboon... that is really dangerous," said the researcher.

A strong concept is presented in the study, according to the experts. According to Fabien Knoll, a paleontologist with the Aragonese Foundation for Research and Development at Dinópolis, a paleontological museum located in Teruel, Spain, "Until now, we didn't have any idea of the possible number of neurons dinosaurs could have," says Knoll. Dinópolis is a paleontological museum.

"It's really refreshing to actually have a neurologist looking at paleontological data," says Stig Walsh, senior curator of vertebrate paleobiology at the National Museums of Scotland, who was also not involved in the work. "It's really refreshing to actually have a neurologist looking at paleontological data." In spite of this, he claims that there are "an awful number of inferences or recommendations based on what is basically one single extrapolation."

As an evolutionary scientist at Johns Hopkins University, Amy Balanoff has mixed feelings about the results. "It's good to have these sorts of facts to back that," she adds, referring to the fact that she believes the T. rex was probably a quite nimble and reasonably clever predator. She points out that a significant portion of the data that Herculano-Houzel used to arrive at her estimations of brain mass are already many years old. The data that Herculano-Houzel utilized originate from data sets that were released in 2013 or before. While Balanoff and colleagues published a big data collection in 2020 that included numerous brain mass estimations for birds and dinosaurs, Herculano-data Houzel's came from previous data sets. According to her and other researchers, the report most certainly understates the actual quantities of dinosaur brains.

Herculano-Houzel predicted that it would have taken a T. rex between four and five years to reach sexual maturity, and that it could have lived up to a maximum of 49 years—which is also comparable to the lifespan of baboons. He arrived at this conclusion by combining previous research with the new estimates of neuron density. If this is the case, it is possible that certain dinosaurs utilized tools (possibly in a manner similar to the way in which crows use sticks to trawl for insects) and passed on their expertise from one generation to the next, much as some current primates do.

However, according to Morhardt, assertions of this unusual kind need a great deal more data to support them. We would need further information from the fossil record. Knoll acknowledges that the usage of tools in particular is "very implausible."

Even if the estimates of neuronal density are able to be sorted out, according to Morhardt, they will not reveal the complete tale of the intelligence of dinosaurs. There are further features of brain physiology that are relevant, such as the manner in which neurons interact with one another. However, she is ecstatic about the prospect that a deeper grasp of the mental acuity of dinosaurs may be attainable as a result of her research. She explains that "studies like this one will only continue to sharpen our grasp of what was and wasn't feasible for incredible beasts like as T. rex."