Gratitude: Uniquely Human or Shared with Animals?


"Two chimps had been shut out of their shelter by mistake during a cold rain storm. They were standing dejeted, water streaming down their shivering bodies, when Professor Köhler chanced to pass." Upon opening the door for the two chimps, Dr. James Leuba recounts, "instead of scampering in without more ado, as many a child would have done, each of them delayed entering the warm shelter long enough to throw its arms around his benefactor in a frenzy of satisfaction."

"Chimpanzees," primatologist Frans de Waal points out, "do not normally hug their caretakers for no reason." It's a compelling image, isn't it? The idea that at least some animals might be capable of feeling and communicating gratitude? If we wish to make an argument that some animals possess at least some sort of proto-gratitude, or the cognitive building blocks required for them to feel and express gratitude, we first have to decide what gratitude really means.

Impala are large antelopes native to Africa that groom eachother. Grooming exchanges among African impala are usually unsolicited: one individual grooms the neck of a second individual, and then the second individual returns the favor, and grooms the first individual for an equivalent amoung of time. Hart and Hart suggested that this mutual grooming behavior serves to remove ticks from parts of the body that an individual can't reach itself.

Vampire bats, as you might expect, survive only on blood, and most feed at least once every three days. And while adult vampire bats regularly miss meals, they need not worry, as other individuals will regurgitate blood to feed them.

While the impala and vampire bat examples are interesting, they can be explained by much a simpler mechanism than gratitude: symmetry-based reciprocity. That is, "if members of a species preferentially direct favors to close associates, the distribution of favors will automatically be reciprocal due to the symmetrical nature of association." In other words, the mutual back-scratching of the impala and blood-vomiting of the vampire bat could simply be correlational: individuals who hang out together will tend to engage in reciprocal interactions, but only because they tend to hang out together. These sorts of interactions do not require any sophisticated mental computation for directing repayment only at certain individuals or for keeping track of services received and rendered over time.

Perhaps it seems like your adopted dog or cat pays special attention to you, perhaps in gratitude for his or her rescue? Bonnie and de Waal write:

Even though we have all heard of (and the authors have personal experience with) pets adopted from a miserable stray existence into the comfort of modern homes, it is possible to tell if their greater-than-average appreciation (e.g. tail wagging, purring) of our care and food has anything to do with gratitude. The simpler alternative is that, after prolonged deprivation, there is a constrast effect that lasts a lifetime, making these animals show greater-than-average expressions of pleasure at receiving a full bowl of food. In humans, no one would confuse pleasure with gratitude. On the other hand, if the pleasure is expressed in a personal manner, aimed specifically at the individual who delivers it, are not we getting closer to gratitude?

ResearchBlogging.orgDe Waal observed the common exchange of food for grooming among chimpanzees in order to determine if the trade of food for grooming is simply the result of proximity (as in the impala or vampire bat), or good feelings (as in the adopted domestic dog), or if it is somehow more computationally intensive, such as requiring the ability to direct reciprocity at specific individuals.

Bundles of leaves and branches were placed into the chimpanzee enclosures after the researchers had identified the patterns of grooming on a specific day. The adult chimps were more likely to share food with individuals who had groomed them earlier that same day. Since the chimps shared their food only with their former grooming partners instead of with just anyone, de Waal reasoned, chimps must keep track of favors given and received, and they must be able to distinguish among different social partners. This form of reciprocity, then, is driven by more than just a good mood.

In another experiment, primatologists Seyfarth and Cheney played recordings of vervet monkey calls and measured the reaction of recently groomed individuals. The type of vocalization that they used was a call used to threaten enemies and to solicit the support of friends, in antipation of a conflict. When the recording was of a previous grooming partner, vervet monkeys paid more attention than when the recordings were of other individuals.

Taken together, these studies indicate that some non-human primates have the long-term memory abilities required for gratitude, as well as the ability to distinguish among individuals. These abilities may be necessary for gratitude, but are they sufficient?

But if gratitude is, as Bonnie and de Waal write, the "glue and lubricant" of human society, then there is one more prerequisite for gratitude: obligation. That is, upon receiving a favor, one must not only desire to repay it, but must be obligated to do so. To not do so would represent a social transgression, worthy of punishment. Indeed, a study of humans by Fehr and Gachter indicated that without the possibility for punishment, the cycle of cooperation breaks down. They interpret this finding as evidence that "altruistic punishment is a key force in the establishment of human cooperation, [and that their] study indicates that there is more at work in sustaining human cooperation" than is offered by mechanisms like kin selection or reciprocal altruism. It is possible, Bonnie and de Waal argue, that "gratitude appears to provide [for cooperation] support from one end, whereas punishment and retribution drive it from the other."

Do animals have gratitude? I think its still an open question. But it is clear that some animals, such as chimpanzees and other non-human primates, seem to possess at least a more basic form of proto-gratitude, based on their ability to keep track of favors given to and received from different individuals.

Krisin E. Bonnie, & Frans B. M. de Waal (2004). Primate Social Reciprocity and the Origin of Gratitude in Robert A. Emmons & Michael E. McCullough (eds.) The Psychology of Gratitude (Oxford University Press), 213-229

DEWAAL, F. (1997). The Chimpanzee's service economy: Food for grooming Evolution and Human Behavior, 18 (6), 375-386 DOI: 10.1016/S1090-5138(97)00085-8

Fehr, E., & Gächter, S. (2002). Altruistic punishment in humans Nature, 415 (6868), 137-140 DOI: 10.1038/415137a

HART, B., & HART, L. (1992). Reciprocal allogrooming in impala, Aepyceros melampus Animal Behaviour, 44 (6), 1073-1083 DOI: 10.1016/S0003-3472(05)80319-7

Wilkinson, G. (1984). Reciprocal food sharing in the vampire bat Nature, 308 (5955), 181-184 DOI: 10.1038/308181a0

Seyfarth RM, & Cheney DL (1984). Grooming, alliances and reciprocal altruism in vervet monkeys. Nature, 308 (5959), 541-3 PMID: 6709060

Image source.


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Do you not believe then that humans, now conditioned by our instant gratification of television and technological advances are in the same boat? I can see how the impala and vampire bat are examples of social mimicry, but on the other hand what the chimps did showed on their part an understanding of the circumstances. The chimps gave their caretaker a hung showing (or in essence what humans perceive) as gratitude because their situational circumstances had improved. Does that not justify the title of gratification?

We'd happily share "gratitude" with animals, but they wouldn't even say "thank you".

By NitricAcid (not verified) on 01 Dec 2010 #permalink

Perhaps human graditude is also just a trick to get cupcakes.

This certainly isn't scientific, but why does my horse, who I've had for 21 years, walk with me with him lips always brushing against the back of my hand? Somebody else feeds him and takes care of his primary needs, but he only does that with me. He drags everybody else who leads him all over the place. Is this affection?

Bonnie with the horse

I would venture to say it is. For the horse he knows that your touch means care and affection for him, so he is acknowledging your presence with his head but to your hand. I believe it is his way of saying, "Hello, wanna pet me today?"

Of course I am an animal lover so everything they do I see something in!

By Bonnie In Dallas (not verified) on 03 Dec 2010 #permalink

I've had cats for most of my life, and I've seen what I believe was an expression of gratitude from a cat exactly once. This happened years ago, but it stood out because it was so unusual.

At the time, I had two cats, and I'd just put down a dish of some kind of treat for them to share. They'd usually eat from the same dish without any problems, but this time one cat was crowding the other one out, so I put down another dish of food. The crowded-out cat moved to the second dish, but she made a detour to purr and nuzzle me first. This wasn't an attempt to get me to put more food down (the dish was already on the floor when she did this, and her actions weren't part of our normal feeding/treats routine), and I think it was more than a simple expression of happiness, since she actually delayed eating for a moment to do it.

I suppose it could have just been some random bit of cat behavior, but it really seemed at the time like she was saying "thank you".

Mathematical models of reciprocity demonstrate that the conditions for reciprocity are so restrictive that it is rarely if ever a robust explanation for observed social responses. Clutton-Brock has recently reviewed the literature on reciprocity concluding that most claims can be explained by simpler mechanisms, in particular, mutualism and manipulation. The work of Fehr and others leaves open the question of whether their models require "group selection" as well as requiring proponents of "altruistic punishment" to delineate the conditions under which the mechanism provides greater benefits than costs to the punisher's fitness. It is, also, important to recall that some primates are "tactile" species; chimps, which I have not studied, are apparently one of these. Ethologically, hugging might represent appeasement (conflict resolution) or tension reduction, etc. DeWaal, Goodall, and others have been criticized by mainstream scientists for many years because of their tendencies to anthropomorphize; these criticisms should require the application of Occam's Razor (principle of parsimony), considering whether simpler mechanisms (e.g., those suggested by Clutton-Brock or, possibly, mechanisms of associative learning) might be sufficient causative explanations for certain non-human primate behaviors. The same scientific principle should be applied to the study of human primate behavior.

By lara B. Jones (not verified) on 04 Dec 2010 #permalink

I think some animals are capable of basic gratitude, such as feeling less threatened by a person that feeds them, but I don't think an animal such as a horse or dog feels gratitude in the same way we do.

For example, dogs learn over their lifetimes the best ways in which to manipulate us into giving them things they desire. That puppy eyed look you get when it's normally "treat time" is simply the dog attempting to get you to give them a treat. They've learned through trial and error (if you had them since they were pups, you'll probably remember them attempting to persuade you with responses such as barks or agressive behavior) that displaying that expression on their face results in you giving them a treat. Yes, that makes them intelligent, but intelligence does not nessarily mean sophisticated emotions, in fact some animals are highly intelligent when it comes to one area of cognition (i.e social skills, audio cognition (i.e parrots), problem solving, etc).

There's also the fact that even if say, a dog, was nearly intelligent as a human, or at least had emotions sophisticated as a humans, do not kid yourself into thinking that a dog would be grateful towards you for imprisoning it in your house, feeding it food that likely tastes worse than stale cheerios, and worst of all, castrating it.

Since Chimpanzee's have a brain that is fairly close to that of humans, it's possible, and perhaps likely that they feel gratitude as we do, but I doubt much less developed animals, such as dogs or horses are capable of such diverse emotions. I'm not denying that many animals feel emotion (dogs included), but the emotion they feel is likely limited to carnal emotions: pleasure, fear and anger (some animals, i.e elephants, seem to indicate the ability to feel a basic sense of sadness at the loss of a fellow member of their 'tribe' or offspring).