What research has been done on attachment types in other primates?
Jaak Panksepp, in Affective Neuroscience: The Foundations of Human and Animal Emotions, describes seven brain systems, "raw feels", that are shared among human and non-human primates. One of these systems is PANIC (he capitalizes the systems' name to differentiate them from the similar terms used in speaking about emotions). He says, "a separation distress PANIC system is important in the elaboration of social-emotional processes related to attachment".