A recent study of a colony of Nazca boobies, a seabird living in the eastern tropical Pacific Ocean, discovered that these birds perpetuate a "cycle of violence". This is a fascinating and very important finding because "It is the first evidence from a wild animal that, as in humans, 'child abuse' can be socially transmitted down the generations". The researchers postulate that "... being a victim of abuse raises levels of stress hormones, and these hormonal levels later trigger aggressive behavior ..." Further research in other species is needed to see how robust this finding is, but once again we see that there is so much we can learn from studying the emotional lives of other animals. 

Teaser image is from here.