Two new studies show that chimpanzees may be aware of the concept of death and may recognize when others have died. These studies were reported in the April 27 issue of Current Biology. Behaviors that suggest this have been exhibited in both wild and captive chimps. The studies point to the behaviors of other chimps leading up to and after the death of a captive chimp. The surviving chimps refused to lay in the spot where the chimp was laying when she died for several days. They also were less active and did not eat as much. The studies also pointed to two wild mother chimps who carried their dead babies for 68 and 19 days respectively.
Chimps are very intelligent creatures. It makes a lot of sense that they would be able to recognize and be aware of the concept of death. The sense of denial exhibited by the two mothers is reminiscent of behaviors shown by humans. They don't want to admit what has happened so they continue on as if it never occurred at all. It is also against the nature of the mothers to abandon their infants. So that adds another even stronger attachment to the equation.