Suicide is empathy.

A rhesus monkey is rewarded with food if it pulls a chain. The chain, however, is connected with a device that shocks another rhesus monkey in an adjoining cage. Because the first monkey was able to recognize the suffering of the second, and the reason for the suffering, it refrained from pulling the chain. One participant stopped pulling the chain, and thus stopped eating, for five days. Another for twelve days.

Preston and de Waal write: “These monkeys were literally starving themselves to prevent the shock to the conspecific.”

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Preston and de Waal, “Empathy: Its Ultimate and Proximate Bases,” Behavioral & Brain Sciences 25, no. 1 (2002).