I once heard former President Clinton speak at Middlebury College and he delivered a speech about the importance of seeing each other and how studies had shown that in the end all humans are genetically 99.9% the same. And, that we should therefore forget our differences and concentrate on our commonalities. I loved this speech for many reasons and was sharing it with a friend, who asked "But do we have to be same for this to matter?"
I was taken aback by her question because to me this really hadn't been the point, but I could understand what she meant. At the same time, we can only understand in the ways that we understand, through the means that we already have. Hence statements like "you can't truly understand someone until you have walked ten miles in his shoes, etc."
Someone, some creature, some thing does not have to be like me for me to respect it, but I will only identify with it and understand it by comparing it to something I already understand -- it is metaphor and simile and we need them to make the connections, to have any insight into things that otherwise are unfamiliar, so while Joan's pug Grifles may not mourn her puppies as they leave one by one in the same way that a human mother would grieve or worry over the absence of a child, she seems to feel something and I call that thing grief because it is all that I know to call it. Alfie may not be human, but when I look in her eyes I see "Alfie" and when I look at Waffles I see "Waffles" and the things that make them unique. Is it behaviors or instincts at work that make them act in the individual ways that they do? Perhaps, but we can also debate whether it is behavior or instincts at work in us as well. What makes us human? What makes them canine? We can debate the theological and philosophical nature of the soul, but I know when I look at my niece, Ellie, her child soul looks back at me and when I look at my pug, Alfie, her soul looks back as well. I have no other words for it. It is a metaphor I understand.