Self-awareness and language are two traits that scientists would say make us human, along with a sense of compassion or empathy, according to Scientific American.
Empathy is defined by Dutch primatologist and ethologist as Franz de Waal as, "the capacity to be affected by and share the emotional state of another, assess the reasons for the other's state and identify with the other, adopting his or her perspective."
How do we measure empathy in animals?
Discovery recently reported that elephants sooth each other by caressing each other with their trunks and emitting a chirp. Birds console each other after a fight and hold what seem to be funerals, according to Daily Mail. Rats enjoy being tickled by each other, gorillas will care for dolls and when one orangutan laughs, the others join in.
Pigs are considered intelligent, social animals, so researchers at Wageningen University in the Netherlands used swine to test pig empathy, according to Scientific American.
Scientists housed pigs in 16 groups of six, then took two pigs from each group and trained them to anticipate something good or something bad. The pigs that were trained to anticipate a good outcome were played music and given a treat. The pigs that were trained to anticipate something bad were also played music, but then given a negative experience like isolation. The music would serve as the trigger for the pigs' emotions, according to Scientific American.
Two of the "naïve pigs" - pigs that weren't trained - were put in with the trained pigs. A few trained pigs reacted as expected to the music (tail wagging and barking for positive or ears back, urinating or defecating for negative). Researchers found that the majority of trained pigs did not anticipate the outcome when they heard the music.
When returned to the pen of six, the naïve pigs demonstrated "emotional contagion" - they shared the emotional response of the other pigs. When a naïve pig was next to a stressed pig, their ears also went back. Even more of a reaction occurred when naïve pigs stood near a happy pig, even though the naïve pigs did not experience the reward or punishment that the trained pigs did.
Isolating pigs and stressing them out on purpose sounds cruel, but according to Scientific American, farming practices are unlikely to change without research like this.
