Animals also 'commit suicide' because of loneliness

Many scientific studies have shown that animals - from primates to dolphins, even squid - are self-aware, so whether or not suicide is they are questions that challenge researchers for years.

According to conventional thinking, 'suicide' is a concept only for humans, medical historian Duncan Wilson at the University of Manchester (UK) said.

However, a series of stories of suicide animals that appeared in the late 1800s will probably make many people look back. It is the case of dogs who seek death right near their master's grave, a cat who also kills himself when his child is gone, or the suicidal horses after years of abuse.

'In animals, when they are born they have certain survival skills , ' Wilson said. For an act classified as suicide, animals know that what they are doing will end their lives.

This kind of abstract thinking can go beyond animal awareness. They will inadvertently find some way to end all when they are in a state of sadness, boredom or loneliness. For example, when losing a friend, dogs sometimes fall into a state of "depression" and give up eating until they "close their eyes".

Thus, suicide is a fairly common phenomenon in the natural world. Thomas Joiner has outlined some specific examples in his book 'Myths of Suicide' .

He pointed out that the body of aphids spontaneously inflated when they felt threatened, protected their brothers or even killed the aphid. In this case, suicide is said to be a survival instinct, a way they 'sacrifice' to protect the community.