This is actually debatable on several fronts.
The “catch all” is that there are entire scores of animals and animal behaviors humans haven’t observed, animals often surprise us even after centuries of observation.
But regardless of what we haven’t seen- we have seen behaviors that could be seen as some sort of “proxy” conflict etc.
Nothing quite so straight forward an analog as a kingdom of ants disguising their soldiers as another hives, or a group of baboons sensing weapons to an unrelated group to fight an enemy. But we do see animals using other animals and other species as tools in their conflicts, even instigating conflict.
Crows and Dolphins are two of nature’s well known manipulators. They at least appear to be able to understand and recognize behavioral patterns on some level, and can and will seemingly manipulate other species to do work on their behalf, even kill for them. This is not the same behavior as we see with scavengers and symbiotic hunting. This is using lures, baits, behavioral triggers, to get another creature to solve a problem.
One species of bird at least, has developed a relationship with human hunters. It quite literally has a specific call it uses to get humans attention. Once the humans follow, it indicates proximity to its goal using different specific calls to signify “warmer.” It locates bee hives. Humans then smoke the bees which allows the humans and the birds to get in to the hive. In many animals exists behavior we could call symbiotic, in which one animal uses the interests of another to achieve its own goals. The bird, near as we know, doesn’t care if the humans achieve what they want- it just needs to use the humans to get what it wants.
In a sense, we could call proxy war a type of symbiotic, or perhaps parasitic relationship. In most proxy wars, either government A supplies B with things like material or knowledge to benefit a conflict that B believes is in its own interests, because the war serves the interests of A; or government A manipulates B into a conflict it may or Kay not have become involved in, because it suits A, but A does not provide any support.
We see these sorts of scenarios in the animal kingdom all the time. Now, there are a couple important things about the barely understood field of animal cognition that apply to this analysis. 1. We don’t know, and without better means cannot definitively prove any sort of intent or even knowledge of consequence on the part of the animals. So unlike humans, it is arguable of an animal understands on any deep level that it is putting another animal at risk or causing harm, or if the animal merely understands its actions as prudent or to its own benefit.
We know animals like Dolphins sometimes, at least SEEM to rescue other animals. Dolphins have, for example, swam to whales trapped in inland water bodies and calling distress, and helped these whales swim out to sea. While this doesn’t prove Dolphins have a greater sort of morality or empathy, it indicates that they may well have some sense of it, as the direct benefit or reasoning for their “rescue” efforts are often not obvious to us beyond simply wanting to help another creature in distress. Which implies they understand some concept of mortality or at least suffering, and can apply it to creatures that aren’t Dolphins.
2. Animal cognition is ripe for assumptions and fallacies. We must understand that firstly, not all shared behaviors or traits that seem the same, are from the same origins. Animals can evolve physical traits or behaviors that are very similar but just happened to appear in both species. Many creatures fly, birds, bugs, bats, squirrels and lizards both glide. But these traits just happened to appear in more than one species, they didn’t come from the same origin. Secondly, two animals may exhibit seemingly identical behavior under seemingly identical scenarios, but the mechanisms that produce those behaviors and the “motivations” can be very different.
An example in humans, is that three humans might watch a news story saying that a certain candidate has won the election. All three start crying. But one is crying because they are overjoyed their candidate won. Another is crying because they are devastated theirs lost, and a third is crying because they feel ashamed their fellow countrymen would vote for the winner. This is 3 members of the same species, reacting to the same stimulus, seemingly the same way, but through very different reasons.
An example in humans, is that three humans might watch a news story saying that a certain candidate has won the election. All three start crying. But one is crying because they are overjoyed their candidate won. Another is crying because they are devastated theirs lost, and a third is crying because they feel ashamed their fellow countrymen would vote for the winner. This is 3 members of the same species, reacting to the same stimulus, seemingly the same way, but through very different reasons.
Now, if we take a human and a dog, the human may be waiting all day, looking out the window for the mail carrier because they are waiting for a very important delivery. Their dog may be waiting all day, looking out the window too. When the mail carrier arrives, both the human and dog might get excited, Juno up and down, run to the door, enthusiastically greet the mail carrier. The dog and human appear to be behaving the same. But is the dog even aware the mail carrier has a function, or what it is? Is the dog watching for a package and enthusiastic to pick it up? Likely not. The dog is likely watching because it’s nature is to keep awareness of its territory and watch for intruders or danger. It goes to greet the mail carrier for possibly many reasons, but one is usually instinct- curiosity, etc etc.
So things become very dicey when we speak about animals, their motivations, a third (3.) thing to keep in mind is that in all but logical terms of organization and very broad relation- most animals and humans differ SUBSTANTIALLY in how we interact with other species, our own, the environment, etc. animals generally (as fat as we know) have no concept of countries or governments. Some have sorts of social orders, some have territories, but even in broad terms these things can mean something completely different to them. Some species for example only care when others from their own species “violate” their space, while others are aggressive to any creature or certain type, etc etc.
So we can’t really compare more complex social interactions and global politics in such ways. The number of animals that are known to produce tools is relatively small, when you look at the the number of animals that produce tools in preparation for an anticipated problem- like a war, that number drops to basically... humans.
Now, let’s just agree and say that only humans fight proxy wars. But what else is on the list of things only humans do? How many animals that lack the biological ability to fly have gained sustained flight? How many animals go to the moon? Do any other animals have organizations dedicated to helping out others in need? Do they try to conserve other species? A debatable one- do other animals create and enjoy and advance art? Music? Do any other animals have systems of morality and philosophy?
For some of these things- maybe? Like my opening says, there’s a lot we don’t know or understand about animals. But near as we can tell- animals don’t seem to have most of these things. So when we asses our species compared to others- we have to be thoughtful. I mean- animals don’t ever run out of gas for their cars, but they also don’t have cars. Because they don’t have cars, they don’t fight wars for fuel right? But there’s two sides to that coin and we can’t just say animals are better because they don’t have cars, or worse because they don’t have cars.
One other thing to understand is that animals, social animals, tend to have an established order. Usually it comes down to whoever is strongest, biggest, most dominant; or a familial hierarchy. Animals tend to form societies based on natural order, whereas humans have all sorts of artificial and symbolic means to determine hierarchy. The leader of the dog pack is whoever takes the role. Genetics is one of the primary components there. Humans, we don’t have such simple rules as those. Ultimately we can distill almost any facet of human society and behavior down to a simple instinct or drive, but there is more to it.
So yes, humans hurt each other and use proxies and such. But we also don’t in a society that is primarily dictated by “law of the jungle.” We have things like elections, trials, debates. If you look at humanity and want to see the bad you will, if you only want to see the good you will. The truth is more complex. There is good and bad. The noble and the repugnant, and often we do one type of deed for the other type of reason. So I don’t know that I can really say this sentiment rings true.
The “catch all” is that there are entire scores of animals and animal behaviors humans haven’t observed, animals often surprise us even after centuries of observation.
But regardless of what we haven’t seen- we have seen behaviors that could be seen as some sort of “proxy” conflict etc.