Sunday, 24 August 2014

Chimp Eyes Show Evolution of Ethics

Chimps show empathy by mimicking pupil size - life - 22 August 2014 - New Scientist

More evidence guaranteed to trigger the avoidance reflex in creationists was published in PLOS ONE this week. It shows two things which any creation pseudo-scientist worthy of the name will need to misrepresent, lie about or ignore altogether. It shows evidence that humans and chimpanzees share a common ancestor and that chimpanzees too have empathetic ability - the basis of a ethics and the ability to make ethical decisions. In other words, chimpanzees have morality and they, along with us, very probably inherited this ability from our common anthropoid ancestor.

The paper showed for the first time that chimpanzees (Pan troglodytes), like humans, subconsciously change their pupil dilation in response to the pupils of the chimpanzee they are interacting with. Pupil dilation is an important clue to the feelings and state of mind of the other person. To see this for yourself, if you have a child, look into their eyes, smile and watch their pupils dilate. It works between two lovers too.


Group-living typically provides benefits to individual group members but also confers costs. To avoid incredulity and betrayal and allow trust and cooperation, individuals must understand the intentions and emotions of their group members. Humans attend to other's eyes and from gaze and pupil-size cues, infer information about the state of mind of the observed. In humans, pupil-size tends to mimic that of the observed. Here we tested whether pupil-mimicry exists in our closest relative, the chimpanzee (P. troglodytes). We conjectured that if pupil-mimicry has adaptive value, e.g. to promote swift communication of inner states and facilitate shared understanding and coordination, pupil-mimicry should emerge within but not across species. Pupillometry data was collected from human and chimpanzee subjects while they observed images of the eyes of both species with dilating/constricting pupils. Both species showed enhanced pupil-mimicry with members of their own species, with effects being strongest in humans and chimpanzee mothers. Pupil-mimicry may be deeply-rooted, but probably gained importance from the point in human evolution where the morphology of our eyes became more prominent. Humans' white sclera surrounding the iris, and the fine muscles around their eyes facilitate non-verbal communication via eye signals.

Kret ME, Tomonaga M, Matsuzawa T (2014) Chimpanzees and Humans Mimic Pupil-Size of Conspecifics. PLoS ONE 9(8): e104886. doi:10.1371/journal.pone.0104886

It has been known for more than a century that the human pupil dilates and contracts in response to mental and emotional activity as well as to changes in light intensity and for several decades that pupil size is related to the difficulty of the task. In 2010, Wolfgang Einhäuser-Treyer, a neurophysicist at Philipps University, Marburg, Germany showed that pupil dilation can betray an individual's decision before it is openly revealed.

All this suggests there was an adaptive advantage in human societies in giving out non-verbal signals showing what was going on at the conscious level inside the brain. It has been suggested that this is the reason why we evolved the white sclera to make the direction of gaze more obvious as well as bringing the pupil into sharper focus for the observer. We gained something by being able to read the mind of our companions and that something is what we call empathy. Empathy is what enables us to apply the 'Golden Rule' by judging the effects of our actions on others - something essential in forming cooperative groups and probably one of the most significant development in our evolution.

Now it seems chimpanzees also have this ability, though maybe not so highly developed because chimpanzees lack the ability to make as much use of more detailed information. But the fact that chimpanzees have the ability suggests they can also judge the effects of their actions on their companions and that that ability had an adaptive advantage. In other words, it suggests chimpanzee societies also requires ethical behaviour to work effectively.

Ethical behaviour (or morality) is, of course, something theologians like to pretend is unique to humans and inexplicable other than as an arbitrary set of rules handed down to mankind by their imaginary creator. Indeed, C.S. Lewis, in a laughable god of the gaps and an arrogant argument from personal incredulity, cited his inability to imagine any other reason for acting ethically other than because the god his parents happened to believe in said he should, as his reason for believing in that god.

It now seems that not only do chimpanzees have that ability but, because it is something they share with humans, so, almost certainly, did our shared common ancestor.

It must be increasingly difficult being a theologian unless one is prepared to adopt a morally and intellectually bankrupt approach to scientific facts.

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  1. Well then.... according to this article, Chimps are more evolved than most Christians.....!!!

  2. Interesting as usual, Rosa! I know of no traits that are unique for humans. Intelligence - at least some other species in the animal "kingdom" also have the same traits and use them too.

    For example empathy - many animals have it and use it. Or spiritual experiences - also other animals seem to have that kind of awe. So what's so special with humans? We who are said to be created in the image of God (ad imaginem Dei), by God Almighty? (Genesis 1:27)

    For those interested in the topic, see: . Here's a quote from that article:

    Since other animals, such as non-human primates, horses, cats and dogs, also possess similar brain structures, it is possible that they too experience mystical moments, and may even have a sense of spiritual oneness, according to [Kevin] Nelson. Marc Bekoff, a professor emeritus of ecology and evolutionary biology at the University of Colorado, Boulder, also believes animals have spiritual experiences, which he defines as experiences that are nonmaterial, intangible, introspective and comparable to what humans have. Both he and primatologist Jane Goodall have observed chimpanzees dancing with total abandon at waterfalls that emerge after heavy rains. Some of the chimps even appear to dance themselves into a trance-like state, as some humans do during religious and cultural rituals. Goodall wondered, "Is it not possible that these (chimpanzee) performances are stimulated by feelings akin to wonder and awe? After a waterfall display the performer may sit on a rock, his eyes following the falling water. What is it, this water?"

    And here's an intriguing article about empathy in animals: . This article is not only about elephants. You can also read about ravens, crows, magpies, scrub jays, mice. rats, cats, dogs, gorillas, orangutans and of course chimps.


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