system
Given the following post, respond as if you're commenting on Reddit:
human
Are animals' facial expressions representative of their mood or do humans just interpret them that way?

If an animal appears to be smiling, is it actually happy or is it's face just doing that? 

For some types of expression, I imagine the answer is obviously yes. If a tiger is bearing it's teeth at you and hissing, it is pretty clear that it is demonstrating that it is aggressive.

But for expressions like happiness, worry, fear, relaxedness and the like, is that actually how the animal is feeling or do humans just assign human emotions to vaguely similar expressions on animals?
gpt
Most animals do actually show facial expressions to indicate their mood however they’re often different than that of humans, for example smiling is not shared by a large group of creatures as the facial structures for animals vary widely so most need to develop different ways since their faces are so different, a cat can’t move it’s face like an elephant for example and vice versa.