In this episode of Discovering Darwin we tackle Chapter VIII - Joy, High Spirits, Love, Tender Feelings, Devotion in Darwin's book The Expression of the Emotions in Man and Animals. In this chapter Charles explores how we express ourselves when we are happy, in particular he discussed the two expressions associated with a happy mental state - smiling and laughing. Mark, Sarah and I explore what a "real" smile looks like, why we fake it sometimes, and why women more often fake it.
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| Clearly a Duchenne "D" smile |
The Duchenne smile is defined by the contraction of the obicular muscles that surround the eyes and the raising of the lips to expose the upper teeth. Darwin describes it as:
Dr. Duchenne repeatedly insists that, under the emotion of joy, the mouth is acted on exclusively by the great zygomatic muscles, which serve to draw the corners backwards and upwards; but judging from the manner in which the upper teeth are always exposed during laughter and broad smiling, as well as from my own sensations, I cannot doubt that some of the muscles running to the upper lip are likewise brought into moderate action. The upper and lower orbicular muscles of the eyes are at the same time more or less contracted...
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| Image from: https://www.earthslab.com/anatomy/orbicularis-oculi/ |
We also discussed laughter and how it may have evolved as a false alarm call. Laughter is found to be exhibited in other apes. Interestingly, the variation in the sounds apes like gorillas, chimpanzees, orangutans, bonobos, and humans make when being tickled follows the same pattern of relatedness seen in the phylogenetic tree based upon genetic relatedness.
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| From Ross, Owren, and Zimmermann (2009) |
Papers we discussed:
The opening and closing theme to Discovering Darwin is "May" by Jared C. Balogh.
Interlude music was Laugh from Lotusland: A musical comedy by Ian Whitcomb
