I’ve always said that we are the only species whose members know they’re going to die. I’m not sure that’s true, of course, but there have been suggestions that some mammals, even if they don’t grasp their own personal mortality, at least understand that death is something final and unique.
Two years ago, Natalie Angier of The New York Times had a piece on this issue, prompted by the death of a baby gorilla in a German zoo whose mother continued to carry the corpse for days, refusing to surrender it to keepers. Angier mentioned work by Karen McComb and her colleagues showing that African elephants preferentially fondle the bones of dead elephants as opposed to bones from other species.
The latest issue of Current Biology has two thanatological notes (thanatology is the scientific study of death) suggesting that chimps, our closest relatives, perceive death as something unique. The first, by Dora Biro et al., is straightforwardly called “Chimpanzee mothers at Bossou, Guinea carry the mummified remains of their dead infants.” The authors report that, in 2003, a respiratory disease killed several chimps in a free-living colony in Bossou. Two of the dead were infants, 1.2 and 2.6 years old. In both cases the mothers continued to carry the dead babies around for several weeks, despite the putrefaction of the corpses. Mothers continued to treat the bodies (which eventually mummified) with care, grooming them and chasing away flies, as well as carrying them in a unique way, gripping the arms of the dead infant between the mother’s head and shoulders (Fig. 1).
Fig. 1. A. Mother carries corpse of her baby who died 17 days earlier. Notice the unique carrying posture. B. Head of mummified infant who was carried for 68 days after death.
The authors speculate that the mothers knew the babies were dead:
An obvious and fascinating question concerns the extent to which Jire and Vuavua “understood” that their offspring were dead. In many ways they treated the corpses as live infants, particularly in the initial phase following death. Nevertheless they may well have been aware that the bodies were inanimate, consequently adopting carrying techniques never normally employed with healthy young (although mothers of handicapped young have also been known to respond appropriately).
I’m not sure that carrying a corpse in a unique way betokens an understanding of death; maybe it’s just the best way to tote around a nonmoving infant who doesn’t smell too good. But it is intriguing.
The second report, “Pan thanatology,” describes the behavior of a group of captive chimps when one of their members, a 50-year old female called Pansy, expired peacefully. After describing the behaviors, the authors reiterate them, drawing parallels with human behavior:
During Pansy’s final days the others were quiet and attentive to her, and they altered their nesting arrangements (respect, care, anticipatory grief). When Pansy died they appeared to test for signs of life by closely inspecting her mouth and manipulating her limbs (test for pulse or breath). Shortly afterwards, the adult male attacked the dead female, possibly attempting to rouse her  (attempted resuscitation); attacks may also have expressed anger or frustration (denial, feelings of anger towards the deceased). The adult daughter remained near the mother’s corpse throughout the night (night-time vigil), while Blossom groomed Chippy [Blossom’s son] for an extraordinary amount of time (consolation, social support). All three chimpanzees changed posture frequently during the night (disturbed sleep). They removed straw from Pansy’s body the next morning (cleaning the body). For weeks post-death, the survivors remained lethargic and quiet, and they ate less than normal (grief, mourning). They avoided sleeping on the deathbed platform for several days (leaving objects or places associated with the deceased untouched).
This is a bit anthropomorphic to me, but doesn’t exceed the bounds of informed speculation. Indeed, the BBC News headline this description as “Chimps ‘feel death like humans'”, and of course it shows nothing of the sort. (The BBC link has a video of the death, which, unfortunately, you can’t access in the U.S. If you do have access to Current Biology, you can see two videos here, including a male attacking Pansy’s body.) UPDATE: The videos are now on YouTube and I’ve embedded them below.
What the BBC headline misses is the ineluctable fact that even if we observe behaviors in other species that are similar to our own, we cannot understand what is going on in the consciousness of chimps. Are they grieving? We won’t know until we can teach chimps to communicate in a sophisticated way with humans, or, more easily but less usefully, observe a similarity in brain activity between the two species evoked by the occurrence of a death.
Although many atheists see our knowledge of death as a blessing, making us realize that life is ephemeral and we should live it to the fullest, I see it as a curse. It takes a certain amount of courage to face the fact that one day we will lose everything we have. Few of us, I think, are enough like Socrates to accept our mortality with equanimity. Yes, our consciousness is gone when we die, and yes, we don’t agonize about our absence from the scene before we were born, but I for one would choose immortality or, barring that, at least merciful ignorance of my finitude.
Three chimps surround Pansy as she dies:
A male attacks Pansy’s corpse:
Anderson, J. R., A. Gillies, and L. C. Lock. 2010. Pan thanatology. Current Biology 20:R349-R351.
Biro, D., T. Humle, K. Koops, C. Sousa, M. Hayashi and T. Matsuzawa. 2010. Chimpanzee mothers at Bossou, Guinea carry the mummified remains of their dead infants. Current Biology 20:R351-R352.
h/t: Matthew Cobb’s Z-letter.