Animals behave suicidally as humans do, according to new research that suggests they could be models for our own behaviour, whether it’s a depressed horse or a whale beaching itself inexplicably. “You begin to challenge the definition of suicide. The body and mind are so damaged by stress and so it leads to self destruction. It’s not necessarily even a choice,” Edmund Ramsden, one of the authors of the study published in the journal Endeavour, told Discovery News. In fact, it leads others to see suicides not as willful acts, but as responses to conditions. In one case, dating back to 1845, a Newfoundland dog was reported to be acting less lively, then threw himself in the water, keeping his limbs still and his head under until he eventually drowned. And pea aphids, when threatened by a lady bud, can explode themselves, protecting their families and sometimes killing the lady bug. Several organisms self-destruct, usually to protect their relatives or save their genes, but in modern humans, it can go wrong: millions of suicides around the world benefit no one, they say. This tells us that suicide is “a fatal consequence of biologically-based and extremely serious illness,” says psychologist Thomas Joiner of Florida State University.