[Animals] Why are some animals smarter than others?

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American Crow (Corvus brachyrhynchos) at the Sutton Avian Research Centre. There are 40 different species of raven.

 

From jackdaws breaking the shell of a nut by throwing it on the ground, to sparrows blocking the sensors of supermarket doors to steal food or blue tits opening the milk cans that the delivery man leaves at the doors of the houses. Even with brains the size of a nut, these animals achieved behaviors and learning that have been studied for decades.

Among birds, ravens are considered the most intelligent animals in the world, surpassing even some children and primates. In fact, various studies have found in recent years that ravens make and use tools or solve puzzles, and other species, such as parrots, have a very diverse vocabulary.

Science has already proven that these birds make good use of their brain cavities and, in fact, have more neurons than many mammals. But what then makes some animals smarter than others?

(Related: They show that the intelligence of crows is comparable to that of chimpanzees)

Years ago it was believed that intelligence was related to brain size. This theory, called the encephalization theory, argues that the 'extra' brain tissue of a larger brain allows more neurons to be dedicated to cognitive tasks, according to researchers from the Center for Ecological Research and Forestry Applications (CREAF).

 

However, until now no scientific evidence was available due, in part, to the difficulty of accounting for neuronal density in different animal species.

Do animals have the capacity to innovate?
Now, new work published in the journal Nature Ecology and Evolution shows, for the first time, that a higher number of neurons is related to one of the main forms of intelligence: the ability to innovate. In turn, this number of neurons is related to a larger brain, both relative to the body and in absolute terms.

"Our results suggest that in corvids and parrots the accumulation of neurons in the pallium is the result of lengthening the time that the chicken needs to develop, once hatched", says Daniel Sol, a scientist at the Higher Council for Scientific Research (CSIC). ) ) and CREAF.

 

THE INCREDIBLE INTELLIGENCE OF NEW CALEDONIAN CROWS
New Caledonian crows are known to use sticks to lure prey out of hiding. However, a recent study suggests that ravens can create better tools with those sticks. These ravens have developed the habit of carving a hook at the end of a branch to better reach their prey. The scientists tested whether the birds distinguished a straight branch from a hooked one. They found that the hook limb is up to 10 times more effective than the straight limb. Ravens not only modify and improve their designs, they probably share their knowledge with other ravens.
Therefore, these results show that the number of neurons in the pallium - an area of the brain that corresponds to higher functions such as learning, different types of memory, intelligence, emotions, language, etc. - are a fine predictor of cognitive ability. of a kind. That is, a greater number of neurons in the pallium implies a greater capacity for innovation. "These results are consistent with the hypothesis that the accumulation of neurons in the pallium takes place in late phases of development," says Sol.

“In turn, the accumulation of neurons in the pallium causes the brain to grow both in absolute and relative terms. Thus, among all the species and lineages studied, the scientists highlight that corvids and parrots are the birds that have a larger brain in relation to the body and also more neurons in the pallium. They are also the ones that have a longer maturation time”, they explain.

(Related: This Amusement Park Uses Disturbance Jackdaws to Pick Up Trash)

On the other hand, “in groups such as pheasants and pigeons, the stage of postnatal development is shorter, which does not allow them to accumulate as many neurons in the pallium. This may explain why they have relatively small brains and are less innovative in their behavior."

 

Towards a new evolutionary model
Also, both corvids and parrots have a longer lifespan. "Living longer increases the value of solving problems through innovation because the time you spend learning a new behavior is offset if the behavior offers benefits for longer." Until now, there was controversy about whether the size of the brain was more important in absolute terms or in relative terms.

"Elephants have a larger brain than humans in absolute terms," says Louis Lefebvre, a psychologist at McGill University (Montreal, Canada) and co-leader of the study; “Does this mean that they are more intelligent than humans? However, what matters most is the relative size of the brain. The human brain contains more neurons in the pallium, making it larger in proportion to our size than that of elephants."

 

Link: https://www.nationalgeographic.es/animales/2022/07/por-que-algunos-animales-son-mas-inteligentes-que-otros