In a debate my father said that only humans do things that are not directly linked to survival(painting, playing musical instruments, singing etc). He said that this is because we are "special" and not like other animals on the planet.
I said that this is only because we have much more developed brain than other animals. But now I'm also interested in one question.
Are there animals who do similar things(not exactly same, of course) not for mating/survival but just because they like it?
I see that Gerardo has said effectively what I was going to: animals don't do things because they have reasoned out that these things will help them survive; they engage in behaviors because these behaviors lead to reward circuitry response and animals who find general categories of behavior rewarding have tended to survive better. Sometimes behaviors that are not directly related to survival trigger the same circuitry.
(P.S.: this is exactly what is happening in humans, too.)
Masturbation is one example, as above; so are animals that 'adopt' either conspecific or heterospecific juveniles who don't belong to them, which is not uncommon in many species. (Barn cats in particular do this often; aside from all the cute Youtube pictures of cats who think ducklings are kittens, it's very common for queens with kittens about the same age to co-nurse them.) You can argue that sociality and taking pleasure in altruistic activities with no immediate personal benefit is a survival adaptation, but that's not a calculation the animal is consciously making at the time.
Animals often have strong aesthetic preferences, especially for conspecifics; female and male animals often prefer traits that don't have anything obvious to do with survival in potential mates, and there is an entire discipline of sexual selection in biology devoted to teasing out why. It's worth noting, however, that in many species it turns out that females have preferences that vary widely for a number of traits, and that female preferences do not always line up to male reality...
Outside of naturalistic social behavior, numerous examples of elephants and chimpanzees creating drawings or paintings in their enclosures without any conscious reinforcement from their keepers have proved interesting reading. There are also examples of animals who keep "pets", including the famous case of Koko the gorilla and her pet kittens. You may find this article, with descriptions and citations of several animals who may or may not be engaging "art" for its own sake, to be a useful read.
Arguably, yes. There numerous species of non-human animals which have been observed to masturbate wikipedia. Non-human animals will frequently choose less-healthy foods over healthy foods. (Offer a cat a raw fish and a can of tuna, most of them will choose the canned tuna every trial even though a diet of only canned tuna would be disastrous due to the high salt content.)
Arguably, these are just instinctive behaviors firing outside the ideal circumstances, but that plus endorphins or species-specific analogues may be as good a definition of acting purely for pleasure as any.
