Behavioural biology has fundamentally changed our scientific understanding of animals. We now doubtlessly better understand their thinking, feelings, and behaviour, and in the process are discovering how similar we really are to each other, indeed to a far greater extent than we could have even a few years ago imagined.
Admittedly, the degree to which this is true is not the same across all animals: we are clearly closer to chimpanzees, dolphins, dogs, or mice than we are to ants, starfish, snails, or amoebas. We are vertebrates, and we are mammals, and we share a comparable brain, hormones, and nervous system with all other creatures in this class. Thought, emotions, and behaviour are all ultimately functions of these systems. The more comparable living beings are in this respect, the more similar they are to each other.