As anybody who has grieved inconsolably over the death of a loved one can attest, extended mourning is, in part, a perverse kind of optimism. Surely this bottomless, unwavering sorrow will amount to something, goes the tape loop. Surely if I keep it up long enough I’ll accomplish my goal, and the person will stop being dead.

Last week the Internet and European news outlets were flooded with poignant photographs of Gana, an 11-year-old gorilla at the Münster Zoo in Germany, holding up the body of her dead baby, Claudio, and pursing her lips toward his lifeless fingers. Claudio died at the age of 3 months of an apparent heart defect, and for days Gana refused to surrender his corpse to zookeepers, a saga that provoked among her throngs of human onlookers admiration and compassion and murmurings that, you see? Gorillas, and probably a lot of other animals as well, have a grasp of their mortality and will grieve for the dead and are really just like us after all.

Nobody knows what emotions swept through Gana’s head and heart as she persisted in cradling and nuzzling the remains of her son. But primatologists do know this: Among nearly all species of apes and monkeys in the wild, a mother will react to the death of her infant as Gana did — by clutching the little decedent to her breast and treating it as though it were still alive. For days or even weeks afterward, she will take it with her everywhere and fight off anything that threatens to snatch it away. “The only time I was ever mobbed by langurs was when I tried to inspect a baby corpse,” said the primatologist Sarah Hrdy. Only gradually will she allow the distance between herself and the ever-gnarlier carcass to grow.