Look at all those people in that thread going "I dont know if animals have the same emotions or just similar ones" or "we can't prove that plants dont feel pain too!" and then splitting hairs in the most asinine pseudophilisophical debates, just so they dont have to engage with the core of the issue, that what they're doing is fucked up.
They know it, deep down, as did I before I went vegan, but it's eye-opening to see it "from the other side".
Yes. Science is the difference between knowing and feeling.
We feel like animals have emotions but is often because we are projecting ourselves on them. We inject emotional motivations on them because of how it makes us feel. Breaking that illusion would likely reduce the emotional benefit we experience from allowing these little creatures in our homes.
From all this research, it seems that the similarities between human and animal emotions might be closer than we would have expected a few decades ago. Animals react to their environments much as humans do. They respond emotionally to others and they evaluate situations in a similar way, becoming stressed and anxious in times of danger. While we may never know exactly how animals feel, studies have found that there are definite behavioural and physiological similarities in emotional expressions between humans and animals. We can thus infer, with quite some confidence, that animals can feel emotions. The more we discover about the behavioural and physiological components of emotions in animals, the more we understand about emotions, including our own ones, and how they affect the way we behave in our world.
You're right, but in that vein it's incredibly difficult to scientifically confirm that other humans have emotions outside of explicit communication. If you follow that line of thinking, you might as well assume that babies can't really feel pain or something (which up until somewhat recently was the going assumption). You might not know, but it's not unreasonable to assume they do unless proven otherwise, even if you don't know what they're feeling or to what extent.