Do animals have emotions?

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Do you think animals have concrete emotions? Today I was petting one of my dogs, and I abruptly stopped, and went to give affection to my other dog. The first dog immediately got up and ran over to me and started rolling around on the floor at my feet, basically begging for attention. This has happened on multiple occassions, like it seems he was jealous. What do you think? Do animals have emotions? Or do they act solely on instinct?