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Ancient Maya sculptures with discernible faces and contexts from different archaeological sites. Source: Science Advances

Study of Maya Statues Shows That Facial Expressions Are Universal

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Researchers have developed a unique experiment to determine the universality of certain emotional expression in the human face. It has long been debated by experts whether emotional expressions can be understood across cultures, or if they can only be understood within a specific social context. Thanks to a selection of Maya sculptures , alongside the latest machine learning tools, an American team has finally been able to prove that many expressions of emotions are indeed universal.

Two American researchers from Berkley University of California, Alan Cowen and Dacher Keltnerset, set out to determine if human expressions are universal, formed as a result of our genetic make-up, or if they are conditioned by our social contexts and values. This problem has proven surprisingly difficult to resolve. Previous tests on this issue have involved the presence of a researcher, which has inadvertently resulted in them “incidentally skewing answers by offering rewards for what they want to find,” reports Phys.Org. In order to ensure objective results, there was a need to collect data from people without contact with the researcher and who were very different from modern Westerners.

Attaining Objective Results Using Maya Sculptures

The researchers decided to select a culture that was very different from modern Western culture. They chose to use examples from Maya culture , one of the greatest Mesoamerican cultures, which flourished centuries ago in what is now the Yucatan, Mexico, Guatemala, and Honduras. The Maya peoples managed to create a unique civilization in an inhospitable environment in the period from 1500 BC to 1600 AD, building spectacular stepped pyramids.

Naturally, no photographs survive from the Maya era, but the Maya were accomplished sculptors and carvers. The researchers focused on sculptures and figures with facial expressions that conveyed basic and easily understandable emotions such as pain, anger, and happiness. In Science Advances they explain that “artistic portrayals of emotional expression in the West have parallels within the ancient Americas, long preceding contact between Western and ancient American civilizations.”

Mapping sculptures along dimensions of perceived facial expression that tend to accord with predicted emotions. (Science Advances)

Mapping sculptures along dimensions of perceived facial expression that tend to accord with predicted emotions. ( Science Advances )

Categorizing the Facial Expressions of Maya Sculptures

Researchers selected 63 Maya figurines and sculptures that date back to 1500 BC, after examining hundreds to see if they were suitable. While these artifacts were long removed from their ancient settings, it is still possible to recognize their emotions. This is because of the naturalistic faces of the sculptures and because many are in poses associated with emotionally charged situations such as “ childbirth, playing a sport, or being held captive,” write the researchers in Science Advances . 

The researchers then categorized them into thirty categories or classes of emotion and eight contexts and took photographs of the figures. Eureka Alert reports that the next stage was to edit these photographs, during which they “separated each sculpture's expression from its context, producing, for example, one image of just the smile and one image of the mother holding the baby, with no expression visible.” They developed two samples of images, one with facial expression and one without.

Modern Americans and Maya

The pictures were then shown to a sample of 325 Amazon Mechanical Turk online workers. They asked the U.S. participants to categorize each image of facial expression and label it. On this label, they were to provide what they believed were the emotions being conveyed by the artwork. Then they were asked to identify the context of the sculpture and the emotions that they felt that they would most likely see. Their responses were analyzed using machine learning technology to determine if they matched the expressions on the Maya figures.

The study concluded that “Ancient American sculpture was found to portray at least three dimensions, or varieties, of facial expression that accord, in terms of the emotions they communicate to Westerners, with Western expectations for the emotions that might unfold in the eight contexts portrayed,” explains the article in Science Advances . For example, the participants labelled the expression of a mother with a child as “elated”. When they saw an image of a Maya mother with a child without any facial expression, they labelled it with the same word. This showed that “facial expressions depicted in 63 sculptures from the ancient Americas tend to accord with Western expectations for emotions that unfold in specific social contexts,” highlight the researchers in Science Advances .

Expression of Suffering. Fold-out plate of weeping children and babies from Darwin's “The Expression of the Emotions in Man and Animals”, his third major work on evolutionary theory. (Wellcome Library / CC BY 4.0)

Expression of Suffering. Fold-out plate of weeping children and babies from Darwin's “The Expression of the Emotions in Man and Animals”, his third major work on evolutionary theory. (Wellcome Library / CC BY 4.0 )

Nature or Nurture: Are Emotional Facial Expressions Universal?

The AAAS release published by Eureka Alert states that “this suggests that emotional expressions can be inferred through universal human themes.” The fact that modern English-speaking people who live in a technologically advanced society can understand the emotions expressed in Ancient Maya art, provides proof that many emotions and facial expressions are indeed universal and that we are programmed by nature to understand them.

The researchers hope to expand the scope of their research. Albert Cowen told Eureka Alert that they “would eventually be interested in replicating this work in other cultures.” Their machine learning tools can help them to determine if emotional expressions are common across different cultures in different eras. This could once and for all resolve the debate over the universality of human emotions and provide a key insight into our nature.

Top image: Ancient Maya sculptures with discernible faces and contexts from different archaeological sites. Source:  Science Advances

By Ed Whelan

Comments

Pete Wagner's picture

But yet there is also a critical distinction, as highlighted in old historical depictions (e.g., old Norse fables), differentiating between loving or innocent smiles and sinister ones, where the latter appear somewhat reptile-like (for lack of a better description).  While this distinction is not politically correct in today’s light, it may date back to the time when ancient Greek statues were destroyed by hammering off the noses, so the upward (innocent) or downward (sinister) turn of them is obfuscated.  May also relate to a “mark of Cain” distinction.  Where Maya relics do not show this distinction, they were not likely dealing with the same good vs. bad dynamics.

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