Further to New Scientist asks What if we could talk to animals?
No one with horse sense should be surprised by this:
Horses share some surprisingly similar facial expressions to humans and chimps, according to new University of Sussex research.
Mammal communication researchers have shown that, like humans, horses use muscles underlying various facial features – including their nostrils, lips and eyes – to alter their facial expressions in a variety of social situations.
The findings, published in PLOS ONE today (05 August 2015), suggest evolutionary parallels in different species in how the face is used for communication.
The study builds on previous research showing that cues from the face are important for horses to communicate, by developing an objective coding system to identify different individual facial expressions on the basis of underlying muscle movement.
The Equine Facial Action Coding System (EquiFACS), as devised by the Sussex team in collaboration with researchers at the University of Portsmouth and Duquesne University, identified 17 “action units” (discrete facial movements) in horses. This compares with 27 in humans, 13 in chimps and 16 in dogs. More.
Note: If facial expression is the only criterion, much data will be lost. Dogs, horses (and cats) communicate via tail movements as well. Humans (and other animals) can read these messages. Chimpanzees don’t have tails, as humans do not, so there is nothing to read. Thus, the chimpanzee might be at an even greater disadvantage in communicating with humans—relative to dogs and horses—than facial data show.
Also, it’s possible that convergent evolution is involved. Do wolves and wild horses show the same characteristics as dogs and domestic horses?
Here’s the abstract:
Although previous studies of horses have investigated their facial expressions in specific contexts, e.g. pain, until now there has been no methodology available that documents all the possible facial movements of the horse and provides a way to record all potential facial configurations. This is essential for an objective description of horse facial expressions across a range of contexts that reflect different emotional states. Facial Action Coding Systems (FACS) provide a systematic methodology of identifying and coding facial expressions on the basis of underlying facial musculature and muscle movement. FACS are anatomically based and document all possible facial movements rather than a configuration of movements associated with a particular situation. Consequently, FACS can be applied as a tool for a wide range of research questions. We developed FACS for the domestic horse (Equus caballus) through anatomical investigation of the underlying musculature and subsequent analysis of naturally occurring behaviour captured on high quality video. Discrete facial movements were identified and described in terms of the underlying muscle contractions, in correspondence with previous FACS systems. The reliability of others to be able to learn this system (EquiFACS) and consistently code behavioural sequences was high—and this included people with no previous experience of horses. A wide range of facial movements were identified, including many that are also seen in primates and other domestic animals (dogs and cats). EquiFACS provides a method that can now be used to document the facial movements associated with different social contexts and thus to address questions relevant to understanding social cognition and comparative psychology, as well as informing current veterinary and animal welfare practices. Open access – ‘EquiFACS: The equine Facial Action Coding System by Jen Wathan, Anne Burrows, Bridget M Waller and Karen McComb is published in PLOS ONE on 05 August 2015 http://dx.plos.org/10.1371/journal.pone.0131738.
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