 More recently, Jaak Panksepp (2004, 2005) has been conducting a research program that he calls “affective neuroscience” and that encompasses direct study of animal emotions (2004), exemplified for example in the experimental investigation of rats “laughing” and seeking further contact in response to tickling by humans (Panksepp &amp; Burgdorf 2003). Over several decades, his work (reviewed in Panksepp 2005) has elucidated the neuro- and molecular-physiological bases of several ‘core emotional systems’ including ‘seeking’, ‘fear’, ‘rage’, ‘lust’, ‘care’, ‘play’, and ‘panic’. Panksepp argues that these are shared by all mammals, and may be more widely shared among vertebrates. 