Crows may be the brains of birds, but feathered creatures can understand the very abstract concept of zero, new research suggests.
The concept of zero is used in the number system and was fully developed in human society around the 5th century AD, or potentially centuries ago. Live science previously reported.. For example, the concept of multiplying 8 by 0 or adding 0 to 10 did not appear before. The concept of “none” or no quantity has probably appeared earlier, but this is different from using zero as a separate “quantity” in its own right.
The idea may sound obvious, but according to the concept of zero as a number, Math It has undergone dramatic changes.
Andreas Nieder, a professor of animal physiology at the Institute of Neurobiology, University of Tubingen, Germany, said: “The special thing about zero is that it doesn’t fit into the routine of counting real objects, like real integers.” In other words, someone counts three apples (1, 2, 3) in a basket. You can, but if the basket is empty, there are no apples to count.
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Zero represents its emptiness, lack of apples, and “obviously very abstract thinking … thinking separated from empirical reality.”And now by looking into brain In the crow, Kneader and his colleagues discovered that avian nerve cells, or neurons, encode “zero” like any other number. The bird’s brain activity pattern also supports the idea that zero falls before the “1” on the number line of crows, so to speak.
The new study was published on June 2nd Journal of Neuroscience, The team conducted an experiment with two male carrion crows (Carrion crowMeanwhile, the bird sat on a perch on a tree and interacted with the computer monitor in front of him. On each trial, a gray screen popped up in front of the crow with 0-4 black dots. This “sample” image was followed by a “test” image containing the same or different numbers of dots.
Crows were trained to peck the screen, move their heads if the two images match, and stay stationary if they don’t match.
In a previous study using the same settings, according to a report published in the journal in 2015, crows received extensive training for experiments and then had a pair of matching and mismatched images in about 75% of the time. It was shown to be able to identify successfully Minutes of the National Academy of Sciences.. This previous study did not include an empty screen to replace zero, but for example, it showed that crows can distinguish between images with three dots and screens with five dots.
The greater the difference between the two sets of points, the more accurately the bird responded. In other words, birds confused closer amounts, such as 2 and 3, and mixed more often than more divergent amounts, such as 1 and 4. This phenomenon is known as the “numerical distance effect” and can be observed in monkeys and humans during similar tests, Kneader told Live Science.
A recent study involving a blank screen “after this training, we found that crows can distinguish zero from other countable numbers,” Kneader said. However, importantly, in trials involving empty screens, birds still showed a numerical distance effect.
This means that birds are more likely to confuse a 0-dot image with a 1-dot image than a 2-dot, 3-dot, or 4-dot image. “This shows that we treat an empty set not just as” nothing “vs.” something “, but actually as a number,” recognizes zero dots close to one dot.
To better understand the brain activity behind these behaviors, the team transplanted a small glass-coated wire into the bird’s brain to record electrical activity while the crow repeated behavioral tests. Did. The selected neurons were located behind the bird’s brain in an area called pallium that processes high levels of cognitive function.
The avian adventitia belongs to a larger brain region called the telencephalon.Humans also have a telencephalon, its cerebral cortex, wrinkled outer layer Human brain, Is a part. However, although both pallium and cortex are in the telencephalon, there are many similarities between the two structures. The cerebral cortex contains six different layers of brain tissue connected by intersecting wires, but the avian adventitia has no layers and instead places neurons in nuclear clusters, Kneader said. Says.
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In a previous 2015 study, the team collected records from Pallium and zoomed in on one important area, especially known as the Nidopalium Caudal (NCL). NCL receives sensory information, including information from the eyes, processes that data and sends it to areas of the brain related to motor function to coordinate physical behavior. (In primates, the prefrontal cortex plays the same role.)
At NCL, the team discovered that certain subgroups of neurons became wild when a certain number of dots were displayed on the screen. For example, some respond to two dots and start firing rapidly, while others kick off with four dots. These neurons appeared to be “tuned” to a certain number. And interestingly, the greater the distance between that preferred number and the number of dots on the screen, the less active those neurons were.
According to Kneader, these patterns of brain activity suggest how crows perceive numbers in relation to each other. “They essentially represent this normal aspect of the number line, and the order is along the number line, so one after two, two after three, and so on,” he says. I did.
In a new study, the team repeated this experiment with the addition of a zero-dot screen. In total, they took records from more than 500 neurons, 233 for one crow and 268 for the other. As before, they found that different subsets of NCL neurons light up in response to different numbers of dots, but in addition, another subset fired in response to a blank screen. These neurons became less active as more dots popped up on the screen, and increased in number as they moved away from zero.
In combination, the authors conclude that the observed patterns of behavior and brain activity do suggest that crows understand the concept of zero. Kneader told Live Science that it’s unclear what usefulness this has for animals. Being able to distinguish between one and two fruits can help with survival, but for example, “I don’t see the direct benefit of these animals not understanding anything in quantity,” he said. ..
Other behavioral studies show The rhesus monkey And Bees It also shows an understanding of zero. Regarding zero-linked brain activity Multiple the study Monkeys, like crows, show that they have neurons that are specially tuned to zero numbers.And more recently, Kneader and his colleagues have shown the same in humans, as described in the journal’s 2018 report. Neuron..
“Ask if an animal understands zero sounds a bit strange at first, because zero is a very special and almost magical number,” says Kneader. But now there is increasing evidence that more animals may understand the concept of zero than scientists initially realized.
Still, Kneader said it would be surprising if animals like amphibians and reptiles could perform mathematical calculations that depended on zero understanding because they were inconsistent with the learning abilities of mammals and birds. But given that birds and mammals split from a common ancestor long before the dinosaurs went extinct, the fact that they share overlapping cognitive abilities is also noteworthy, Kneader said.
“That’s the fascinating aspect. evolution Obviously, we have independently discovered different anatomical methods to equip those birds and mammals with high levels of cognitive function. ”
Originally published in Live Science.
Crows understand the “concept of zero” (despite the bird’s brain)
Source link Crows understand the “concept of zero” (despite the bird’s brain)