How Do Chimpanzees Mourn Their Dead?

A baby chimpanzee was killed by a male chimpanzee yesterday at the Los Angeles Zoo (link).

This is yet another case of infanticide in chimpanzees, which is a behavioural trait frequently observed both in the wild and captivity.  In almost every observed case of chimpanzee infanticide, the killer is an adult male and the victim is not their offspring.  That is why when this Los Angeles Zoo killing hit my radar I was not surprised to find out that the perpetrator was an adult male and the infant was not his.  Although this is a tragedy for the zoo, as stated above, infanticide is fairly common in chimpanzee society and likely represents an evolutionary adaptation for males to improve individual fitness.

However, what did interest me about this story was how the chimpanzee mother reacted to the death of her 3 month old infant.

Primatologists have recently become interested in thanatology – the study of death.  It is believed that by studying the way our closest relatives learn about and cope with death, we can gain insights into the development of how humans learn and cope with death.  At the Los Angeles Zoo the mother and grandmother of the murdered infant were allowed to keep the infant over night in order to mourn their loss.  The Great Ape Team in charge of the chimpanzees claimed that the mother and grandmother have been inconsolably sobbing.  Although it is impossible to fully understand their thought process, it is obvious that they understand that their infant is dead – not sleeping – and will not be waking up.

Mourning the death of a loved one is something most people think of as a solely a human ability.  However, chimpanzees clearly demonstrate that they understand death to some extent and mourn their dead.  In one of the most amazing chimpanzee videos available on the internet, captured by the Max Planck Institute for Evolutionary Anthropology, you get to watch as a mother comes to the realization that her infant is dead and will not be waking up.  She sits by her infant for hours as she comes to this realization before carrying her infant on her back and joining the rest of the troop.  In the morning it was discovered that she had left the infant behind.  Her mourning period was over.  You can watch the video:

Although it is clear that chimpanzees mourn their dead in unique, and perhaps culturally influenced ways, monkeys do not seem to mourn their dead or acknowledge death in the same way.  Baboons, for example, seem to continue to treat a dead infant – or individual – in a similar way to someone who is sleeping.  A mother will carry their infant as they would a healthy infant for a period of time before realizing that the infant is non-responsive.  Eventually the dead individual will be left behind, but no monkey in the group mourns.  A colleague of mine who has done work in Ghana echoed this fact to me earlier in the year when she recalled an experience studying colobus monkeys.

So what does this mean?  Well, more research on the way our closest ancestors mourn death is obviously necessary, but from what we know it is clear that they recognize death and death severely impacts their life.  Also, individuals clearly display a prolonged mourning period if the individual that died was important to them or related to them.  What I am interested in knowing (and I’ll admit it may be impossible to know) is do chimpanzees realize they will die one day?  When a mother loses her infant, she is clearly traumatized when she understands that he/she won’t wake up again but while realizing this does she also realize that death is inevitable?  My guess is as good as anyones but if I was a betting man I’d say no.

I think what this tells us is that there are several behavioural similarities between humans and chimpanzees in terms of how we deal with death and cope with death.  However, I think it is also likely that chimpanzees do not experience the crushing reality that death is inevitable.  This is probably uniquely human.  I think once a species realizes that death is inevitable there have to be evolutionary mechanisms to deal with this mentally.  For humans, I think that evolutionary mechanism was spirituality and/or religion.  While chimpanzees show no signs of ‘spiritual behaviour’, there is definitely evidence that humans are hard wired for it.  From an evolutionary perspective it is obvious why more spiritually inclined individuals would be selected for once we began to realize that death was inevitable.  This selection process was probably a quick and powerful one, which could also be why religious belief is still exceptionally strong today, despite the overwhelming evidence that no religion is true.

I’m sure I will revisit this topic at another point, I feel like there is a lot to unpack and discuss, but for now I will leave you with one more thing to ponder.  If we are spiritual and our closest ancestors don’t seem to be, at what point in our evolutionary history did this transition occur?

 

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About Cadell Last
I am a science educator, freelance science writer, and founder of The Advanced Apes based in Toronto, Ontario. In the past my academic research focused on the evolution, ecology, and behaviour of non-human primates (i.e., chimpanzees, gorillas, ring-tailed lemurs). Currently, my official blog, The Ratchet, can be found via The Advanced Apes and Svbtle. I enjoy exploring recent research in human evolutionary sciences, as well as biology, ecology, astronomy, physics, and computer science. My work has been featured in Scientific American, American Humanist, Richard Dawkins Foundation for Reason and Science, and Jane Goodall Institute of Canada. I am also exploring science popularization in new mediums in collaboration with PBS Digital Studios with an animated YouTube channel. You can contact me on Twitter (@cadelllast) or via email: cadell.last@gmail.com

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