Can pets read human emotions?

I have always believed without a doubt that animals can read your emotions! I can feel what my animals are thinking and they seem to be able to sense the same thing about me. I also think that there might be a biological component to some of their awareness into our emotions as well, such as smelling certain kinds of chemical changes in our bodies when our emotions change. I also think that body language says a lot to our animals. I think that they are much more aware of emotions than people may realize.