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| Blue streaked cleaner wrasse (Labroides dimidiatus) |
It's been a long time now since we began to realise that humans are not the only intelligent species. Astonishingly though, we still find creationists and even sane mainstream Christians citing the 'uniqueness' of human intelligence and consciousness as evidence that humans were specially created, separate from other animals, so can't possibly share a common ancestor with them.
First, we discovered that chimpanzees could recognise themselves in a mirror, and Jane Goodall famously saw then fashioning tools from sticks. Hardly surprising given that they are our nearest evolutionary relatives. Over the years, more and more animals have been added to the list of intelligent, even tool-making species. The list now includes dolphins, elephants, different crow species, pigeons even ants, and manta rays have displayed unusual behaviour in front of mirrors.
Dolphins will even have sex in front of a mirror apparently for the fun of watching themselves do it, so there is no doubt that they recognise themselves and their partners.
And now we may have to add another species - a small, finger-long fish to the list of self-aware species.
A story which has popped back into the social media again, following an belated article in The Japan Times, raises some interesting questions about the uniqueness or otherwise of self-awareness (and so a level of intelligence) in animals other than humans. This is the report published last August that a small fish, the blue streaked cleaner wrasse (Labroides dimidiatus) passed the 'mirror test'. The experiment was set up by a mixed team or German and Japanese researchers working in Osaka, Japan.
Abstract
The ability to perceive and recognise a reflected mirror image as self (mirror self-recognition, MSR) is considered a hallmark of cognition across species. Although MSR has been reported in mammals and birds, it is not known to occur in any other major taxon. A factor potentially limiting the ability to test for MSR is that the established assay for MSR, the mark test, shows an interpretation bias towards animals with the dexterity (or limbs) required to touch a mark. Here, we show that the cleaner wrasse fish, Labroides dimidiatus, passes through all phases of the mark test: (i) social reactions towards the reflection, (ii) repeated idiosyncratic behaviours towards the mirror (contingency testing), and (iii) frequent observation of their reflection. When subsequently provided with a coloured tag, individuals attempt to remove the mark in the presence of a mirror but show no response towards transparent marks, or to coloured marks in the absence of a mirror. This remarkable finding presents a challenge to our interpretation of the mark test – do we accept that these behavioural responses in the mark test, which are taken as evidence of self-recognition in other species, mean that fish are self-aware? Or do we conclude that these behavioural patterns have a basis in a cognitive process other than self-recognition? If the former, what does this mean for our understanding of animal intelligence? If the latter, what does this mean for our application and interpretation of the mark test as a metric for animal cognitive abilities?
Masanori Kohda, Hatta Takashi, Tmohiro Takeyama, Satoshi Awata, Hirokazu Tanaka, Jun-ya Asai, Alex Jordan
Cleaner wrasse pass the mark test. What are the implications for consciousness and self-awareness testing in animals?
PLoS Biol 17(2): e3000021. https://doi.org/10.1371/journal.pbio.3000021
Copyright: © 2018 The authors/funders
Open Access.
Reprinted under a Creative Commons Attribution 4.0 International License (CC-BY 4.0).
The experiment was simple in concept. Wrasse were tagged with a markers, some visible and some invisible. Some were placed in a tank with a mirror and some without.
Those with visible tags, having seen themselves in a mirror, tried to remove the tag by rubbing themselves against rocks. Those with no mirror displayed no such behaviour. Those with invisible tags made no attempt to remove the tags either in the presence of mirror or when mirrors were absent.
Although this experiment is not conclusive, it is highly suggestive that these small fish have self-awareness as defined by the mirror test.
So where does that leave theists with their view that humans are uniquely self-aware, conscious and intelligent?
It leaves it in tatters, of course, just as did the recognition of the close relationship between humans and the African great apes based on multiple strands of evidence, not just the fossil record showing gradual divergence, but on the genetic, physiological, anatomical and geographical evidence.
On the day after Charles Darwin's birthday, it is a pleasure to be able to report that humans, like the rest of nature, are a product of an evolutionary process that connects us to the rest of life on Earth, as did the report I commented upon yesterday that added yet more confirmation of our closeness to our close cousins, the chimpanzee.
It's a pleasure to show the arrogant anthropocentrism of Bible-based superstition, that has done so much harm to our planet home, to be absolutely and comprehensively wrong.
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