We can measure some of it, recreate it, but at the end of the day the very nature of observation is dependence what people have witnessed. We're not talking about a few anomalous incidents, however, but well known phenomena anyone who studies animal behavior rather than just anatomy can attest.

I wouldn't say they're NOTHING like ours, but perhaps we're getting into an area of semantics; it would be pointless to try and quantify the extent similarities are and aren't present, because emotion isn't something tangible and precisely measurable. My initial response was taking issue with the attitude I've observed in some biologists to reduce animals to nothing more than instinct and hormones while elevating the animal homo sapiens to some kind of qualitatively different status. In many respects I do see valid distinctions between us and other animals, but this isn't one of them, and I don't think any of them are anatomical or hereditary.