Posted by tags: cognition, behavior, self-recognition, self awareness, tool use, memory, brain architecture, birds, European magpie, Pica pica, researchblogging.org
Figure 1. European magpie, Pica pica, with yellow mark [larger view].
DOI: 10.1371/journal.pbio.0060202.
Birds have been disparaged publicly as “bird brains” for so long that most people have lost the ability to view them as intelligent and sentient beings. However, a group of researchers in Germany have conducted a series of studies with several captive European magpies, Pica pica, that challenge the average person’s view of birds and their cognitive abilities.
It is widely accepted in the scientific community that self-awareness is prerequisite for the development of consciousness. Previously, only mammals — humans and several of their cousins, chimpanzees and orangutans, as well as dolphins and elephants — were observed to have self-awareness by demonstrating that they could recognize themselves in a mirror.
However, a new study by a research group in Germany reveals that birds apparently also evolved self-recognition.
“[Our research] shows that the line leading to humans is not as special as many thought,” pointed out lead researcher Helmut Prior of the Institute of Psychology at Goethe University in Frankfurt, Germany.
To do their research, Prior and his colleagues carried out a series of tests with five hand-raised European magpies. In one test, the researchers placed yellow or red stickers on the birds so they could only be seen in a mirror (figure 1 & figure 2);
Figure 2. Examples of the Behaviors That Were Used for Quantitative
Analysis.
(A) Attempt to reach the mark with the beak; (B) touching the mark area with the foot; (C) touching the breast region outside the marked area; (D) touching other parts of the body. Behaviors (A) and (B) entered the analysis as mark-directed behavior; behaviors (C) and (D) and similar actions towards other parts of the body were considered self-directed, but not related to the mark.
DOI: 10.1371/journal.pbio.0060202.
As you can see in the above image, the magpies became focused on removing the stickers after they saw them in the mirror. The birds tried to scratch the stickers off with their claws and pick them off with their beaks. After the bird succeeded in removing a sticker, these behaviors stopped.
The researchers also found that the birds ignored the stickers when they could not see their reflection in a mirror (when the backside of the mirror faced them instead of the reflective surface), or when the stickers were black in color.
These studies demonstrate that the birds not only could recognize themselves in a mirror, but they also could use that information to remove a foreign object from their feathers.
Some people think that self-awareness is a function of brain size. This is often expressed as the percentage of an animals’ total body weight since otherwise, there is no realistic way to compare brain sizes between disparate taxa. Among mammals that show self-awareness, humans’ brains comprise 21 percent of their total body weight, while chimpanzees’ brains are only 8 percent of their total body weight, bottlenosed dolphins’ brains are 9 percent of their total body weight and elephants’ brains are the smallest at only 1.6 percent of their total body weight.
Compare these values to domestic housecats: their brain size is 8 percent of their total body weight, yet housecats do not convincingly demonstrate self-awareness.
Using this scale, birds have very large brains when compared to mammals. For example, the European magpie’s brain consists of 31 percent of their total body weight and the brain of African grey parrots is 22.6 percent of their total body weight. Irene Pepperberg’s talented talking parrot, Alex, was an African grey parrot.
In contrast, other people think that brain architecture itself is essential for the development of consciousness. Humans and other mammals possess a distinct layered brain, with an outer neocortex that is essential for higher cognitive functioning. Because birds lack a distinct neocortex, people have thought they were unable to think, therefore, they were given the misnomer, “bird brains.” Yet, as numerous behavioral studies have demonstrated, birds perceive the world similarly to mammals and have similar cognitive and neural processing abilities, and are even capable of making their own tools — a behavioral trait that nearly all mammals lack and thus, was long thought to separate humans from all other animals.
But these studies demonstrate that even though birds lack a neocortex, at least the corvids possess the ability to recognize themselves — a necessary prerequisite for consciousness.
“This is a remarkable capability that is at least a pre-requisite of self-recognition and might play a role in perspective taking,” the research team wrote in their paper.
During the previous decade, cognitive and neurobiological studies have demonstrated that birds and mammals faced similar selection pressures to develop complex cognitive abilities, resulting in the evolution of a comparable neural architecture of their forebrain association areas as well as their cognitive operations. This high degree of evolutionary convergence is especially visible for the cognitive abilities of corvids, such as magpies, and apes. By demonstrating self-recognition in the mirror, these magpies show that even the neural capacity for distinguishing self and others has evolved independently in the two vertebrate classes and that a mammalian-style neocortex is not a prerequisite for self-recognition.
“After finding this kind of intelligence in apes, many people thought it had developed once in one evolutionary line with humans at the end. The bird studies show it has developed at least twice.”
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Source
Prior, H., Schwarz, A., Güntürkün, O. (2008). Mirror-Induced Behavior in the Magpie (Pica pica): Evidence of Self-Recognition. PLoS Biology, 6(8), e202. DOI: 10.1371/journal.pbio.0060202.
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