Death in dolphins: do they understand they are mortal?

REPORTS of dolphins interacting with dead members of their pod are raising questions about whether cetaceans understand the concept of death. Bottlenose dolphins in western Greece have been seen reacting to death differently depending on whether a pod member has died suddenly or after a longer period of illness, New Scientist has learned.

Interpreting animal behaviour after the death of a companion is fraught with difficulty. Death is rarely observed in the wild, and it is easy to erroneously attribute human emotions to animals. Nevertheless, several species of intelligent, social animals, such as gorillas, chimps and elephants can display particular behaviours when an animal dies - behaviours which some have interpreted as akin to mourning. Taken together with a growing number of reports of cetaceans interacting with dead animals and the discovery that they have specialised neurons linked to empathy and intuition, the Greek study suggests dolphins may have a complex - and even sophisticated - reaction to death.

Joan Gonzalvo of the Tethys Research Institute based in Milan, Italy, has been observing the bottlenose dolphin (Tursiops truncatus) population in the Amvrakikos gulf since 2006. In July 2007, he and his team of Earthwatch Institute volunteers saw a mother interact with her dead newborn calf. She lifted the corpse above the surface, in an apparent attempt to get it to breathe (see photo). "This was repeated over and over again, sometimes frantically, during two days of observation," says Gonzalvo. "The mother never separated from her calf." The team heard her calling to it while she touched it with her snout and pectoral fins.

The newborn had a large bruise on its lower jaw, suggesting it may have been killed by another dolphin. "Infanticide has been reported in this species," says Gonzalvo. Aware of the dangers of investing animal behaviour with human emotions, he nonetheless suggests the mother may have been mourning the sudden death: "[She] seemed unable to accept the death."

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