Those faces you make when you taste something unexpectedly bitter? Your horse makes them, too.
That’s what researchers at the University of Lethbridge in Canada discovered by videotaping and analyzing the reactions of horses who had three different solutions delivered into their mouths via syringe: sweet sucrose, bitter quinine and plain water to serve as a control.
The researchers observed that horses responded to the sweet-tasting solution with “sucrose bobs,” pricking their ears, bobbing their heads and sticking out their tongues slightly, as if they were licking their lips. After the bitter solution was administered, the horses tended to pin their ears, open their mouths wide and stick their tongues out, an expression known as the “quinine gape.”
Previous research has shown that rodents as well as humans and other primates display the same facial reactions to these tastes. The fact that horses do, too, shows that expressions related to taste are widely displayed among animals and are enabled by common taste-receptor genes for sweet and bitter substances, say the researchers.
Reference: “Sucrose bobs and quinine gapes: Horse (Equus caballus) responses to taste support phylogenetic similarity in taste reactivity,” Behavioural Brain Research, November 2013
This article first appeared in EQUUS issue #441.