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Mirror Self-Recognition in Birds
Alfredo Pereira Jr
Thursday, 21 August 2008 14:25 UTC
Mirror-Induced Behavior in the Magpie (Pica pica): Evidence of Self-Recognition
Prior H, Schwarz A, Güntürkün O PLoS Biology Vol. 6, No. 8, e202 doi:10.1371/journal.pbio.0060202
Comparative studies suggest that at least some bird species have evolved mental skills similar to those found in humans and apes. This is indicated by feats such as tool use, episodic-like memory, and the ability to use one’s own experience in predicting the behavior of conspecifics. It is, however, not yet clear whether these skills are accompanied by an understanding of the self. In apes, self-directed behavior in response to a mirror has been taken as evidence of self-recognition. We investigated mirror-induced behavior in the magpie, a songbird species from the crow family. As in apes, some individuals behaved in front of the mirror as if they were testing behavioral contingencies. When provided with a mark, magpies showed spontaneous mark-directed behavior. Our findings provide the first evidence of mirror self-recognition in a non-mammalian species. They suggest that essential components of human self-recognition have evolved independently in different vertebrate classes with a separate evolutionary history.
Author Summary
A crucial step in the emergence of self-recognition is the understanding that one’s own mirror reflection does not represent another individual but oneself. In nonhuman species and in children, the “mark test” has been used as an indicator of self-recognition. In these experiments, subjects are placed in front of a mirror and provided with a mark that cannot be seen directly but is visible in the mirror. Mirror self-recognition has been shown in apes and, recently, in dolphins and elephants. Although experimental evidence in nonmammalian species has been lacking, some birds from the corvid family show skill in tasks that require perspective taking, a likely prerequisite for the occurrence of mirror self-recognition. Using the mark test, we obtained evidence for mirror self-recognition in the European Magpie, Pica pica. This finding shows that elaborate cognitive skills arose independently in corvids and primates, taxonomic groups with an evolutionary history that diverged about 300 million years ago. It further proves that the neocortex is not a prerequisite for self-recognition.
Introduction
Since the pioneering work by Gallup 1, a number of studies have investigated the occurrence of mirror-induced self-directed behavior in animals of a great range of species. Most animals exposed to a mirror respond with social behavior, e.g., aggressive displays, and continue to do so during repeated testing. In a few ape species, however, behavior changes over repeated presentations with a mirror. Social behavior decreases, and the mirror is used for exploration of the own body. This suggestive evidence of self-recognition is further corroborated by the mirror and mark test. If an individual is experimentally provided with a mark that cannot be directly seen but is, however, visible in the mirror, increased exploration of the own body and self-directed actions towards the mark suggest that the mirror image is being perceived as self. Fairly clear evidence of this has been obtained for chimpanzees 1, orang-utans 2, and pygmy chimpanzees 3. In gorillas and gibbons, some authors reported failure of self-recognition [4,5] whereas others reported positive findings in at least one individual [6,7]. It should be mentioned that even in the chimpanzee, the species most studied and with the most convincing findings, clear-cut evidence of self-recognition is not obtained in all individuals tested. Prevalence is about 75% in young adults and considerably less in young and aging individuals 8. Findings suggestive of self-recognition in mammals other than apes have been reported for dolphins 9 and elephants 10. In monkeys, nonprimate mammals, and in a number of bird species, exploration of the mirror and social displays were observed, but no hints at mirror-induced self-directed behavior have been obtained 5. Does this mean a cognitive Rubicon with apes and a few other species with complex social behavior on one side and the rest of the animal kingdom on the other side? This might imply that animal self-recognition is restricted to mammals with large brains and highly evolved social cognition but absent from animals without a neocortex.
Within humans and apes, self-recognition might reflect a homologous trait, whereas findings in other mammals hint at a convergent evolution. A likely reason for such convergent evolution of self-recognition in dolphins and elephants is the convergent evolution of complex social understanding and empathetic behavior 10. If self-recognition is linked to highly developed social understanding, some birds species, in particular from the corvid family, are likely candidates for self-recognition, too. A number of studies from the past years have demonstrated an elaborated understanding of social relations, in particular during competition for food. It has been shown that own experience in pilfering caches facilitates predicting similar behavior in others 11, and that magpies 12 and scrub jays 13 remember who of their conspecifics observed them during storing. Thus, food-storing birds might be particularly apt in empathy and perspective taking, which have been suggested to coevolve with mirror self-recognition 14.
An investigation of self-recognition in corvids is not only of interest regarding the convergent evolution of social intelligence, it is also valuable for an understanding of the general principles that govern cognitive evolution and their underlying neural mechanisms. Mammals and birds inherited the same brain components from their last common ancestor nearly 300 million years ago and have since then independently developed a relatively large forebrain pallium. However, both classes differ substantially with regard to the internal organization of their pallium, with birds lacking a laminated cortex but having developed an organization of clustered forebrain entities instead 15. In some groups of birds and mammals, such as corvids and apes, respectively, brain to-body ratios are especially high 16, and these animals are able to generate the same complex cognitive skills 17. This is indicated by feats such as tool use and tool manufacture [18,19], episodic-like memory 20, and the ability to use own experience in predicting the behavior of conspecifics 11. Although it has been shown that some birds, e.g., Grey Parrots 21, use mirrors with skill in order to localize and discriminate objects, no experimental evidence of self-recognition has been obtained in birds so far.
In the present study, magpies were chosen for several reasons. They are food-storing corvids that compete with conspecifics for individually cached and memorized hoards. They thus live under ecological conditions that favor the evolution of social intelligence [12,17]. They achieve the highest level of Piagetian object permanence 22, which is also achieved by apes, but not by monkeys. In addition to showing social understanding during competition for food 12, magpies are curious and prone to approach new situations, making them ideally suited for an experiment that requires spontaneous interaction with a new and puzzling context.
Mirror behavior in animals goes through several stages. In all species tested so far, inspection of the mirror and social behavior has been observed. In species with mirror self-recognition, some of the individuals also show evidence of inspection of their own body and testing for behavioral contingencies after familiarization with the mirror. For example, they move back and forth in front of the mirror, and this might indicate that they check to which degree the mirror image is coupled to their own movement. Individuals achieving this stage often also pass the mirror and mark test.
(Thanks to Malcolm Dean for forwarding the notice to me)
Updated 21 August 2008 14:25 UTC
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[Michael Butler]
“In terms of the definition or use of the word consciousness/unconsciousness, I haven’t been in the philosophical discussion on this subject and so could not comment – indeed I left philosophy because I got bored of such discussions. On the other hand you appear to be preaching to the converted – I certainly would not wish to advocate a dualist perspective of life and nor I think would many people on this forum, but I also would not wish to deny other people’s beliefs whilst we do not have a standard modern physical theory”….
[Philip Benjamin]
I practically agree with everything in your post [except, I am responsible only for whatever is in my name Philip Benjamin. There are many,I know, particularly in the medical field who view Bio Dark-matter as a refreshing frontier for investigation. There are others who find “substance” in the Dark Body for their world views. There are people from different religious or faith backgrounds who are constantly in touch with me over the Invisible Homo sapiens- curiously skeptical!! Trash for one is treaure for another].
[Michael Butler]
Theoretical physics such as supersymmetry (SUSY), dark matter, bioelectromagnetics etc. are all currently uncertain, incompletely confirmed or investigated in a biased fashion – all I wished to say was that one should keep one’s mind open, since there are currently a lot of theories without much actual progress. In such circumstances it is surely safer to err on scepticism when it comes to meta-theories which seek to unify these.
[Philip Benjamin]
I am in perfect agreement. I am only proposing the feasibility of a bio dark-matter realm. It may or may not be the same as what astrophysics or theoretical physics is after. Perhaps axion-like particles may suffice all requirements for all fields. If so, it is rather “awkward”, to berate the least, that such humongous cosmic quantities of dark matter has nothing to do with the biosphere!! One way of interaction is the “subjective”(i.e. mystic) mode.A few physicists have put out some literature attributing mystic or paranormal powers to Dark Matter. The other way is the “objective” bio-physico-chemical mode. That has to come through dark- matter chemistry.
Chemistry means “chemical bonds”, which in turn mean “electron configurations of duets and octets”, which point to electron “spin”, the exclusion princioples etc. Monopoles could be the force carrying particles. Then there is the possibility of “bond stretching”, “bond dissociation” etc involving EM and non-EM linkages, opening up possibilities of explaining such bio phenomena as ELF photons, and paranormal events as OBE etc.
I wish you look into these seriously, since you are more oriented toward the “physical” than the metaphysical.
[Michael Butler]
Although your comment that subjective speculations should not be ‘elevated to science’ is of course true for an enterprise (i.e. science) which prises itself on objectivity, I think most people here are interested in uncovering the physical/biological foundations of such subjectivity.
[Philip Benjamin]
I cannot agree with you more! It seems I have given the false impression of being a “gadfly” for consciousness studies. That is disappointing. Far from it. I only point out that “phlogiston” turned out to be “oxygen” and “vitalist Energy” turned out to be just “Heat” at least for the conversion of ammonium cyanate (inorganic)to urea (organic). [Writing from memory, the spellings and specifics may be wrong, pardon me].
So much excellent work has been done by so many, even taking there name and fame in their hands! But, is it necessary to load a simple English word as “consciousness” with so much magic and mist? All such thunder and wonder over a single word is beyond comprehension. Almost all of these loaded meanings can be explained “objectively” via Dark Matter Chemistries and all its ramifications.
[Michael Butler]We cannot deny that we feel, think and behave as subjects, whether these feelings and thoughts are emergent properties of physics (or not), and so we must eventually find a way to fit social and cultural aspects into science otherwise we will not have a complete understanding of our daily reality. This may be biased towards which subject matter we focus upon, but, as long as we realise this, who cares?
[Philip Benjamin]
What seems to be beyond “Light” neuro-science may be within the reach of “Dark” Neuroscience. Is that a “gadfly” spoiling the “apothecary’s ointment”? What “Ordinary” materialism cannot grasp, “Extraordinary” materialism can effectively grapple. What is being touted as the mysterious “consciousness” loaded with out-of-the-earth adjectives may be a total body phenomenon of ‘entangled’ resonance relationships beteween “light” bodies and their “dark” counterparts. Phlogiston is out. Oxygen is in.
That is all.
Best regards,
Philip Benjamin.
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Hi Philip,
Great, glad we agree, but I think we’ll just have to agree to disagree on the dark matter subject! I’m happy enough with the basic idea, but I think there is still so much we do not know about ‘normal’ condensed matter in biological systems that I wouldn’t want to jump to conclusions from a perspective of theoretical particle/unified theory physics. For instance there may be simpler solutions to account for strange perceptive experiences such as OBE – as an example there is indirect evidence that low frequency acoustic standing waves may account for the experience of ghosts. I agree that we must understand the interactions of all types energy (photons, matter waves, gravity etc.) when it comes to biology but it will have to be tested one step at a time!
All the best,
Michael -
[Michael Butler] Earlier post:
“Although your comment that subjective speculations should not be ‘elevated to science’ is of course true for an enterprise (i.e. science) which prises itself on objectivity, I think most people here are interested in uncovering the physical/biological foundations of such subjectivity”.[Philip Benjamin]
Very true. But suddenly for no rhyme or reason, the “physical” is anything but physical! It takes the “monstrous”, nebulous, dualistic, metaphysical, mystical,holy-macaronic, Platonic “form” expressed by the simple English word “consciousness” which is loaded with unseemely attributes, appropriations and approximations never before heard of or meant for. In simple terms, it is de facto a “Dark Matter” of some kind- the bio kind- that they are dealing with. Just call it so and proceed on a reduction ad absurdum basis with that. Suppose it exists (with no reference to Astrophysics or theoretical physics), then will there be a Dark Chemistry?
[Michael Butler] Recent Post:
Great, glad we agree, but I think we’ll just have to agree to disagree on the dark matter subject! I’m happy enough with the basic idea, but I think there is still so much we do not know about ‘normal’ condensed matter in biological systems that I wouldn’t want to jump to conclusions from a perspective of theoretical particle/unified theory physics.
[Philip Benjamin]
I am not talking about the dark matter of physics. It may or may not be the same. That is besides the point. What I am suggesting is let Chemical Biology and Biochemistry be ‘bold’ just as Astrophysics or Theoretical Physics is, to assume that a Dark Bio-Matter exists.
[Michael Butler]
For instance, there may be simpler solutions to account for strange perceptive experiences such as OBE – as an example there is indirect evidence that low frequency acoustic standing waves may account for the experience of GHOSTS. I agree that we must understand the interactions of all types energy (photons, matter waves, gravity etc.) when it comes to biology but it will have to be tested one step at a time!
[Philip Benjamin]
I am familiar with the work of Professor Michael Persinger, Laurentian University, Canada (your Link). Nothing can be “simpler” than to look for ‘dark chemical bonds’ dissociating to various degrees under complex weak magnetic fields. This is testable if biophoton emission rates are also included. It easily predicts a ratio of biophoton emission rate (an order of magnitude) between plants and humans which closely agrees with all experimental values. That is “testing one step at atime”.
Mirror Self-Recognition in Birds by Alfredo Pereira Jr is an attempt to look for a physical basis. But, how does it lead to the “SELF”? What is the response of the animals to parallel mirror images? How do they respond to a series of TV camera images? Ratiocination is unknown to animals and plants.
There is a graded “dimensional” difference between the taxa. That can be explained in simple physical terms when bio dark matter particles are incorporated in a differential manner governed by genetics.
Biophysics should serious consider the quantum aspects of Dark Matter Chemistry with the ‘forgotten’ monopoles substituting for electric charges. They are inseparable cousins!
All the best,
Philip Benjamin
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