I doubt there’s an organismal biologist alive who hasn’t wondered if some other species of animals know of their own mortality, and if so which ones. I’ve always thought it was the great and unique tragedy of the human species that we alone know that our own lives are finite. That of course, has given rise to all sorts of peculiar behaviors, including much religious doctrine.
Not having access to the consciousness of any creature except H. sapiens, we’re not sure. Certainly some animals act as if they understand death: dying chimps are surrounded by what looks to be caregivers, elephants fondle the bones of other elephants, and mother primates can cling to dead infants for days. I even once saw a squirrel dragging the carcass of another squirrel across the quad of my university, but had no idea what that meant. But none of these acts mean that these creatures conceive of death the way humans do. A piece at New Scientist, discussing the behavior of a mother gorilla and her dead infant, said this:
It could be grief, but it could equally be a morbid fascination with death. Or it could just be confusion.
A lifeless corpse of a conspecific could just engender curiosity, and a gorilla mother’s clinging to her dead baby could reflect maternal instinct gone awry. And even if animals do feel a kind of mourning, that doesn’t mean that they know that they themselves will one day pass on. In fact, I still think that we’re still the only species aware of our individual finitude.
But Matt Walker, editor of BBC Nature, has just revived this question in a piece called “Curious incident of a dead giraffe,” a summary of a paper by Fred Bercovitch that was just published online in the African Journal of Ecology (reference and link below). Bercovitch’s paper reports three incidents in which giraffe’s show “mourning behavior” similar to that of elephants and chimpanzees.
Here’s one report from the paper:
At the Soysambu Conservancy, Kenya, Muller (2010) observed a Rothschild’s giraffe, G. c. rothschildii, cow remaining vigilant in proximity to her dead calf over a period of four consecutive days. The neonatal calf had a deformed hind leg and its mother had remained within 20 m of her offspring for the duration of the calf’s life. When little over a month old, the calf apparently died from natural causes. When sighted, the calf carcass was surrounded by 17 extremely vigilant and agitated female giraffe, one of which was the calf’s mother. On the third day following the death, the half-eaten carcass was found about 50 m from the original location, with the mother standing vigilant next to it. On the next day, the carcass was no longer in the vicinity, but the mother was still in the area. Muller (2010) concluded that the extensive vigilance, nuzzling, sniffing and inspection of the carcass by the mother, as well as by other giraffe, indicates that closer family ties characterize giraffe than often assumed.
In a second case, a herd of giraffe stopped to inspect the 3-week-old carcass of a young female Namibian giraffe (G. c. angolensis), bending down in a way giraffes do only when drinking or feeding on soil or bones. The third case involved a young female giraffe who had just given birth to an infant, apparently stillborn. She sniffed the dead calf and apparently stayed in the vicinity of the calf for over two hours. Here’s a photo of her inspecting her infant:
The BBC Nature report says that this may imply that animals have a “mental model of death”:
The behaviour is striking for a number of reasons.
Females giraffes rarely spend any time alone, yet this individual spent hours with her dead calf away from other females.
Giraffes rarely splay their legs to bend down, apart from when to drink or feed.
And apart from two other similar incidences, giraffes have not been seen intensively investigating their dead.
But none of that convinces me that this is anything other than simple curiosity (“what is that thing that looks like us lying on the ground?”) or maternal behavior and puzzlement over a newborn not moving. Indeed, Bercovitch himself urges caution, calling for scientists to collect more data from other species on the reaction of animals to dead conspecifics. All he concludes from these observations is that “a mother/offspring bond develops from birth and is more pronounced than often presumed.”
Yet I’m not sure that even that collection of data can tell us what we want to know, which is what resides in the consciousness of animals faced with a dead conspecific. If primates show behavior similar to human mourning, though, one might at least conclude that they feel the loss of an individual they knew well. Whether that means that they know death in the way we do, though, would remain unresolved, as would the question of whether any animals besides us knows that our own lives are finite. To know that means probing the consciousness of other species, something that’s nearly impossible to do.
I am curious whether readers have experiences with animals that bear on this question.
h/t: Matthew Cobb
Bercovitch, F. B. 2012. Giraffe cow reaction to the death of her newborn calf. African J. Ecology. Online: DOI: 10.1111/aje.12016