Raccoons Are Rather Smart With Less Than 3% As Many Neurons as Humans

 A recent article in the Independent is entitled "I studied the brains of raccoons. Here’s what it tells us about human intelligence." We have an article written by a neuroscientist (Kelly Lambert) who correctly describes how smart raccoons are; but her article may lead to wrong ideas about the brains of raccoons. 

Speaking of raccoons, the neuroscientist states, "the species – Procyon lotor – is known for its impressive intelligence, curiosity and problem-solving skills." We have part of the article suggesting that raccoons were so clever that they were not used as research subjects, because the raccoons kept figuring out ways to escape through ventilation ducts in research laboratories.  We read this:

"And the role confusion continues today with glimpses of humanlike behaviors in raccoons as they enter our living spaces. One report described raccoons interacting with playground equipment at a child care center on Canada’s west coast in ways similar to human children, and even breaking into classrooms as if they were auditing the morning lesson....After introducing young raccoons to slinkies, puzzles and blocks, I sat in awe as they interacted with these objects with the focused enthusiasm of preschoolers on a mission....Early behavioral research suggested that raccoons can learn a task, walk away and later return to solve it accurately – as if having mentally rehearsed the solution. In contrast, other species, including dogs and rats, needed to maintain continuous focus. Scientists have speculated that raccoons have mental imagery capabilities similar to humans."

But none of this should be possible, according to "brains make minds" claims -- because raccoons have fewer than 3% of the cerebral cortex neurons that humans have. Humans are believed to have about 86 billion neurons, with about 20 billion of them in the cerebral cortex. But according to a paper co-authored by Lambert, "The raccoon cerebral cortex has an average 438 million neurons." 

Does Lambert tell us in her Independent article that raccoons have less than 3% of the cerebral cortex neurons of humans? She does not. Instead she gives us the following paragraph that seems designed to give us the wrong idea about raccoon brains: 

"Working with neuroscientist Suzana Herculano-Houzel, my laboratory at the University of Richmond has found that raccoons pack an astonishing number of neurons – an amount comparable to primates – into their brains. Scaled up to size, a raccoon brain would contain roughly the same number of neurons as a human brain."

The statement seems designed to give the casual reader the idea that raccoons have neurons numbers similar to humans. They do not. Raccoons have less than 3% of the cerebral cortex neurons of humans. And comparing total neurons in raccoons and humans, we find that the total number of neurons in raccoons (about 2 billion) is less than 3% of the total number of neurons in humans.  The page here gives the total numbers. 

Trying to explain why raccoons with so few neurons can be so smart, Lambert states this: 

"In collaboration with ecologist Sara Benson-Abram’s research team, we also found that raccoons with more sophisticated cognitive abilities had more neural cells in the hippocampus, reinforcing the idea that their learning and memory capacities map onto similar brain systems as those in people. Taxi drivers in London, who frequently use their knowledge of the 25,000 streets in London, also have a larger hippocampal area."

We have no paper reference for these claims, which are not well-founded. The first claim by Lambert is probably referring to the paper here, co-authored by her, Sara Benson-Abram and others. Its study group sizes were way too small for the study to qualify as any decent evidence for the claim that "that raccoons with more sophisticated cognitive abilities had more neural cells in the hippocampus." The study group size corresponding to "raccoons with more sophisticated cognitive abilities" was a study group of only 7 animals. No claim about a greater number of hippocampal neurons should be taken seriously unless that study group was 2 or 3 times larger, consisting of at least 15 or 20 animals. 

There is also no robust evidence that "taxi drivers in London, who frequently use their knowledge of the 25,000 streets in London, also have a larger hippocampal area." Such claims are based on the study  “Navigation-related structural change in the hippocampi of taxi drivers” which found no notable difference outside of the hippocampus, a tiny region of the brain. Even in that area, the study says “the analysis revealed no difference in the overall volume of the hippocampi between taxi drivers and controls.” The study's unremarkable results are shown in the graph below. 

The anterior part of the left half of the hippocampus was about 25% smaller for taxi drivers (100 versus 80), but the posterior part of the right half of the hippocampus was slightly larger (about 77 versus 67). Overall, the hippocampus of the taxi drivers was about the same as for the controls who were not taxi drivers, as we can see from the graph above, in which the dark bars have about the same area as the lighter bars. 

By claiming that "taxi drivers in London, who frequently use their knowledge of the 25,000 streets in London, also have a larger hippocampal area," Lambert is repeating one of the groundless "old wives' tales" of neuroscience, which is something that neuroscientists frequently do. 

Raccoons are not the only species that acts in a very smart way, despite having less than 3% of the neurons of humans.  Ravens show a wealth of high-level cognitive abilities, even though they have only about as many neurons as raccoons -- about 2 billion, which is less than 3% of the number of neurons that humans have. 

Postscript: Speaking of organisms that do mighty mental feats with tiny brains, below is a quote from a scientific paper:

"Who knew that bees with their tiny brains could memorize flowers and also human faces, solve problems of arithmetic, and learn to use tools. Until the last few years it was thought that social insects were governed only by instinct. It was all nothing more than innate behaviors. But recent research tells us something very different. As Princeton Professor Lars Chittka explains, 'Much of the workings of the bee’s mind can be understood only when one considers the natural challenges of the constantly changing market economy in which it must operate. The pressures of operating in this setting are often expressed in terms of physical performance. For example, a bee can carry its own body weight in nectar and or pollen; it may need to visit 1,000 flowers and fly 10 kilometers to fill its honey stomach only once; and 100 such trips may be required to generate a teaspoon of honey. Less appreciated are the mental efforts required along the way: in visiting 1,000 flowers, the bee has to work 1,000 floral ‘puzzle boxes’ whose mechanics can be as complicated as operating a lock and no two flowers species are quite alike in the mechanics that have to learned to gain access.'  Similarly, Monarch butterflies with brains the size of the head of a straight pin somehow in their annual 2,500 mile migration from the U.S. and Canada to the forests of central Mexico where they hibernate, fly day by day from the same tree their parents flew to the next tree their parents stopped for the night. And if that tree falls or is cut down, the next generation will pick a new tree and their progeny will stop there as well. How can they possibly even know which direction to fly, let alone identify one tree from another as they travel?"

When They Get Data Suggesting Brains Don't Make Minds, They Repackage It As "Brains Make Minds"

The "brains make minds" dogma is so entrenched in academia that many scientists feel afraid to challenge it, on the grounds that becoming a heretic is not a good career move.  What often happens is that scientists will get some observational result that is inconsistent with the dogma that brains make minds, and such scientists will try to repackage this result as a "brains make minds" result.  Examples of this can be found in the discussion of humans who think very well and have good intelligence despite having lost half, most or almost all of their brains because of disease or surgery to stop severe seizures. Rather than listening to what nature is suggesting by such cases (that the brain is not the source of the mind), our scientists may try to repackage such results as something like "evidence of the amazing plasticity of the brain, which can work well even when most of it has been lost."  Similarly, if someone claims your teeth produce your mind, and you lose most of your teeth, he may say, "Well, isn't that amazing: it requires just a few teeth for you to be smart!" 

In today's science news, we have an example of such repackaging of results to fit the standard narrative (even when the results suggest that narrative is wrong). It is a news story entitled "Surprise! Complex Decision Making Found in Predatory Worms With Just 302 Neurons."  No evidence has been produced that such decision-making occurs through neurons. We read, "Instead of looking at actual neurons and cell connections for signs of decision making, the team looked at the behavior of P. pacificus instead – specifically, how it chose to use its biting capabilities when confronted with different types of threat."  We read about the worms taking "two different strategies" when biting, one involving "biting to devour" and the other involving "biting to deter."  We read this:

"By observing where P. pacificus worms laid their eggs, and how their behavior changed when a bacterial food source was nearby, the scientists determined that bites on adult C. elegans were intended to drive them away – in other words, they weren't simply failed attempts to kill these competitors. While we're used to such decision making from vertebrates, it hasn't previously been clear that worms had the brainpower to proverbially weigh up the pros, cons, and consequences of particular actions in this way."

If we knew such worms produced such "complex decision making" by the action of neurons, would we then be entitled to say, "Complex decision making can arise from only 302 neurons"?  No, not at all. Very many or most of the neurons of any organism are presumably dedicated to things such as muscle movement, sensory perception and autonomic function. We should presume that 90% of the neurons in such worms are tied up in such things. If you then wanted to claim that complex decision making came from the neurons of such worms, you would have to presume that a mere 30 or so neurons were producing such complex decisions. 

Such a claim would be laughable. Humans have no understanding of how billions of neurons in a human brain could produce any such thing as thinking, understanding or decision making. To claim that complex decision making can come from only a very small number of neurons in a worm seems absurd, rather like thinking that someone with only a few dozen muscle cells could lift an air conditioner up above his head.

The writer of today's new story should have recognized that these results conflict with claims that minds are produced by brains. Instead, the results were repackaged to conform with the "brains make minds" dogma. So the beginning of the news story read like this:

"As scientists continue to discover more about the brain and how it works, it can help to know just how much brain matter is required to perform certain functions – and to be able to make complex decisions, it turns out just 302 neurons may be required."

See here for another example of complex thought from tiny animals (ravens). An article in Knowable Magazine suggests that tiny spiders are capable of complex thought. We read this:

"There is this general idea that probably spiders are too small, that you need some kind of a critical mass of brain tissue to be able to perform complex behaviors,' says arachnologist and evolutionary biologist Dimitar Dimitrov of the University Museum of Bergen in Norway. 'But I think spiders are one case where this general idea is challenged. Some small things are actually capable of doing very complex stuff.'  Behaviors that can be described as 'cognitive,' as opposed to automatic responses, could be fairly common among spiders, says Dimitrov, coauthor of a study on spider diversity published in the 2021 Annual Review of Entomology."

In one test of intelligence, tiny mouse lemurs with brains 1/200 the size of chimpanzees did about as well as the chimpanzees  We read this:

"The results of the new study show that despite their smaller brains lemurs' average cognitive performance in the tests of the PCTB was not fundamentally different from the performances of the other primate species. This is even true for mouse lemurs, which have brains about 200 times smaller than those of chimpanzees and orangutans."

This result is what we might expect under the hypothesis that brains do not make minds, but not at all what we would expect under the claim that brains make minds. 

Raven Smarts Defy Prevailing Brain Dogmas

 Professors who lack any understanding of how a brain could produce intelligence like to use localization claims to try to impress us. When a localization claim occurs, a professor will try to impress us with his understanding by claiming that some particular mental function comes from some particular part of a brain.  After hearing such claims, someone might say, "These guys may not the how of cognition, but at least they know the where."  But such localization claims do not hold up well to scrutiny. 

One of the main localization claims that has long been made by neuroscientists is a claim that thought or decision making come from the front top part of the brain, the prefrontal cortex. In my post here I cite many neuroscience papers giving evidence that conflicts with such a claim.  For example, the scientific paper here tells us that patients with prefrontal damage "often have a remarkable absence of intellectual impairment, as measured by conventional IQ tests." The paper here tested IQ for 156 Vietnam veterans who had undergone frontal lobe brain injury during combat. If you do the math using Figure 5 in this paper, you get an average IQ of 98, only two points lower than average. You could plausibly explain that 2 point difference purely by assuming that those who got injured had a very slightly lower average intelligence (a plausible assumption given that smarter people would be more likely to have smart behavior reducing their chance of injury). Similarly, this study checked the IQ of 7 patients with prefrontal cortex damage, and found that they had an average IQ of 101.

Claims that thought comes from the prefrontal cortex have always been inconsistent with the observational reality that certain birds behave with a rather keen intelligence, despite a lack of any cerebral cortex. An article on Aeon mentions how there is little correlation between brain size and intelligence, or a correlation between intelligence and the size of a frontal cortex. The article states the following:

"Some of the most perspicacious animals are the corvids – crows, ravens, and rooks – which have brains less than 1 per cent the size of a human brain, but still perform feats of cognition comparable to chimpanzees and gorillas. Behavioural studies have shown that these birds can make and use tools, and recognise people on the street, feats that even many primates are not known to achieve."

An article on the Science Daily site states the following:

"Some birds are capable of astonishing cognitive performances to rival those of higher developed mammals such as primates. For example, ravens recognise themselves in the mirror and plan for the future. They are also able to put themselves in the position of others, recognise causalities and draw conclusions. Pigeons can learn English spelling up to the level of six-year-old children."

There are two separate reasons why the cognitive abilities of ravens, crows and rooks argue against prevailing brain dogmas:  

(1) According to prevailing brain dogmas, animals such as ravens with so tiny a brain should not be anywhere near as smart as they are.

(2) According to prevailing brain dogmas, animals such as ravens with no brain cortex should not be anywhere near as smart as they are. 

In a recent "perspective" article in the journal Science,  a scientist makes a very strange attempt to get us to believe that crows have a cortex. The opinion piece is entitled, "Birds do have a brain cortex -- and think."  The author states that "birds, and particularly corvids (such as ravens), are as cognitively capable as monkeys and even great apes."  Using a tricky choice of words that might fool the average reader into thinking that some birds have more neurons than creatures such as humans, the author states, "Because their neurons are smaller, the pallium of songbirds and parrots actually comprises many more information-processing neuronal units than the equivalent-sized mammalian cortices."  Do not be fooled by this language.  The wikipedia.org page here lists the number of neurons in rooks, ravens and parrots as about  1 or 2 billion, and the number of neurons in a human as 86 billion. So humans have more than forty times more neurons than animals such as ravens and parrots. 

The author's attempt to argue that birds have a cortex is not persuasive.  Referrring to a part of the bird brain called the pallium, she states, "Birds do have a cerebral cortex, in the sense that both their pallium and the mammalian counterpart are enormous neuronal populations derived from the same dorsal half of the second neuromere in neural tube development."  But that's rather like saying that your ten-year-old owns an automobile, in the sense that a bicycle is a wheeled transportation vehicle capable of moving fast like an automobile.  The cortex is defined as a distinctive layer of cells on the outside edge of a brain.  Birds do not have such a distinctive layer of cells on the outside edge of their brains. So the very many scientists who have stated that birds do not have a cerebral cortex have spoken correctly. 

The author attempts to persuade us that the pallium of a bird's brain is kind of like a cortex, by making this dubious claim: "Nieder et al. show that the bird pallium has neurons that represent what it perceives—a hallmark of consciousness."  While we have good reason to think that the smarter birds such as ravens are conscious, there is no good evidence that any neurons of any organism represent something that the organism perceived.  When we look at the reference to the paper by Nieder and his colleagues, we find that it tested only two animals. 15 animals per study group is the minimum for a moderately reliable neuroscience experimental research paper. 

Another article in the journal Science is just as silly as the one I just discussed.  The article is entitled "Newfound brain structure explains why some birds are so smart—and maybe even self-aware." The article contradicts the other Science article by referring to a lack of a neocortex in birds.  The article refers to a paper by Onur Güntürkün and others that obscurely refers to "hitherto unknown neuroarchitecture of the avian sensory forebrain that is composed of iteratively organized canonical circuits within tangentially organized lamina-like and orthogonally positioned column-like entities."

Another article quotes this Onur Güntürkün speaking rather more clearly:

" 'Here, too, the structure was shown to consist of columns, in which signals are transmitted from top to bottom and vice versa, and long horizontal fibres,'  explains Onur Güntürkün. However, this structure is only found in the sensory areas of the avian brain. Other areas, such as associative areas, are organised in a different way."

Of course, the mere existence of such column-like structures does nothing at all to explain the smarts of birds like ravens, particularly since such structures are found only in sensory areas.  There is no possible physical arrangement of neurons that would do anything at all to explain anything like intelligence in any organism. So the  Science article headline claiming that  "newfound brain structure explains why some birds are so smart" is baloney. 

Postscript: A new scientific paper states that despite having tiny brains, mouse lemurs perform pretty much as well as primates with brains hundreds of times larger:

"Using a comprehensive standardized test series of cognitive experiments, the so-called 'Primate Cognition Test Battery' (PCTB), small children, great apes as well as baboons and macaques have already been tested for their cognitive abilities in the physical and social domain...For the first time, researchers of the 'Behavioral Ecology and Sociobiology Unit' of the DPZ have now tested three lemur species with the PCTB...The results of the new study show that despite their smaller brains lemurs' average cognitive performance in the tests of the PCTB was not fundamentally different from the performances of the other primate species. This is even true for mouse lemurs, which have brains about 200 times smaller than those of chimpanzees and orangutans. Only in tests examining spatial reasoning primate species with larger brains performed better. However, no systematic differences in species performances were ...found for the understanding of causal and numerical relationships nor in tests of the social domain."

Another study finds that even when ravens are only four months old, they have cognitive skills that rival those of great apes.