For quite an interesting read on this idea of empathy in animals, there’s the fascinating article “Evolutionary Aspects of Love and Empathy” in the Journal of Social and Evolutionary Systems, Volume 15 Number 4 353-370. The author says for instance that human love evolved on the basis of the mother/infant relation, dependent on empathy as a mode of perception of the infant’s state and needs. And he asserts widespread empathy among animals, similarly. But he doesn’t provide any specific examples.
I wanted to find more detail. In 1959, it turns out, a researcher trained rats to get food by pressing a lever. Remarkably, if they observed another rat getting electrically shocked at the same time, the observing rat would flinch and stop pressing the lever. This is open to interpretation as to the rat’s precise motivation, but still this is intriguing.
Since then other clever studies have shown evidence of empathy in mice, elephants and chimps, among others.