Over the decades, scientists have held a literal mirror up to various animals to find out if their minds have some sort of representation of themselves.
Elephantsmonkeys, dolphinsEurasian reefs and cleaner wrasse are just some of the menagerie to join humans and chimpanzees in this exclusive club, each reacting to its reflection in a way that shows understanding that it represents itself.
Scientists have now put Adélie penguins to the test, with mixed results. Although it may be premature to conclude that penguins have a sense of self-awareness, the research team still believes there is enough evidence to consider it plausible.
Created in the 1970s by Gordon Gallup, the mirror test has become a classic experiment to demonstrate self-awareness in animals. The method is relatively straightforward. Animals are first habituated to a mirror to get used to its presence and reflectivity. When the test subject is sedated, a clear mark is placed somewhere on the body, where they cannot see it directly. By seeing the mark in the mirror, a self-aware animal will behave in a way that shows they are aware that it is their body that is being marked, and not another individual.
As intuitive as it may seem to assume that reactions to a reflection under different circumstances may indicate some kind of distinction within the self, the test is not without its limitations. Yet it remains one of the few ways we can begin to probe the thoughts of another mind.
In a preliminary study awaiting peer review, a team led by Prabir Ghosh Dastidar of India’s Ministry of Geosciences introduced wild Adélie penguins (Pygoscelis adeliae) to his own reflections during a series of experiments.
Penguins are highly social animals, with Antarctic species relying on colonial whining to endure the freezing extremes of winter. These animals are also relatively easy to test in a wild situation, unlike many other mirror tests that have required the animals to be in captivity.
A waddling of 12 penguins was exposed to the mirror under different conditions. When exposed as a group, there was little reaction, but when isolated by cardboard enclosures and individually exposed to the mirror, the animals examined their reflections.
“The penguins made rapid movements of their heads, flippers or bodies, some of which appeared to be gestures,” the team writes in the paper. “Many of these gestures and movements were quickly repeated, but strikingly, the visual attention of all the penguins in question was fixed on their images throughout their performance.”
The birds did not attempt to contact or show any aggression towards their reflection, suggesting that perhaps they “knew” on some level that the bird in the mirror was neither friend nor foe, leaving only themselves.
When they were ‘tagged’ with a red bib, the penguins failed to react to the change in appearance.
The team admits that there is anecdotal evidence that not all penguins can even see red, so they are not sure about this result.
“Such experiments should be better designed in the future,” suggest Dastidar and colleagues, however, “our investigations lead us to tentatively suggest that Adélie penguins may be self-aware, as indicated by their responses to their own images in a mirror.”
Since its inception half a century ago, there has been growing evidence that the mirror test is not as clear-cut as suggested. Many animals known to be highly social fail the test, including monkeys, unless they are first trained to use a mirror.
Animals that we’re pretty sure are self-aware have failed it too, including gorillas.
Take dogs for example. They are capable of empathy, a quality that also involves a sense of self and others, but they usually fail the mirror test.
“I thought that because dogs are much less sensitive to visual stimuli than, for example, humans and many monkeys are, it is likely that the failure of this and other species in the mirror test is mainly due to the sensory modality chosen by the investigator to test self-awareness and not necessarily to the absence of this latter,” Tomsk State University evolutionary biologist Roberto Cazzolla Gatti explained in 2015.
Gatti tested this with a sniff test similar to the mirror test for dogs. The dogs were tested to see how they reacted to displaced snow that was marked with their own or other dogs’ urine. Sure enough, the canines spent much more time smelling the urine samples of the other dogs.
“This test provides significant evidence of self-awareness in dogs and may play a crucial role in showing that this capacity is not a specific trait of only great apes, humans and a few other animals, but it depends on the way scientists try to confirm it, Gatti said.
Other tests have since supported the idea that dogs have a clear sense of self, although it may not be visually based.
Moreover, even our own children can fail to pass the mirror test, with a number not passing until the age of six in some countries. Thus, although the mirror test may be able to indicate the presence of some self-awareness, if it fails, it does not seem to confirm the lack of this quality which is so important in social intercourse.
The original creator of the mirror test is skeptical of the penguin results so far.
“Penguins may actually be capable of self-recognition,” Gallup said New Scientist. “But that would require a lot more serious science than what’s in this paper.”
In light of its complexity, it may be that, like many other traits, self-awareness exists as a spectrum rather than a dichotomy as the mirror test suggests. This would mean that we need new experiments to investigate this aspect of consciousness.
This research can be read through bioRxiv and is awaiting peer review.