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I had a rough idea of a species that has a tendency to blackmail other species into feeding it. The concept was a tree-dwelling species, a larger one that has few predators among the trees to worry about, that will harass a stronger land-based species into feeding it by threatening to help a predator find it otherwise. For now call this tree species a 'monkey' just to avoid pronoun confusion below, though I'm not committed to it looking or behaving exactly as a monkey.

These 'monkeys' prey on at least one smaller land based predator that relies heavily on camouflage, for example a lynx or other smaller feline. Call this species a 'cat', though again it doesn't have to be feline in nature.

When the 'cat' secures a kill the monkey will show up at a lower branch and effectively demand the cat offer it a small amount of meat from its kill. If the cat doesn't provide the monkey a bribe the monkey will follow it from above and make a constant call that a predator will be attracted to. Effectively the monkey will help larger land predators to find, stalk, and kill the cat unless/until the cat bribes the monkey to go away with food.

In this scenario the monkey is a threat because it can follow the cat anywhere and the cat's camouflage doesn't work as well against a birds eye view as it does against land predators. Thus a species that usually survives by hiding from its predators now has something giving away its presence to those predators. The cat could potentially still get away from the monkey before a predator reaches it if it moves fast enough to out pace the monkey, but the cat usually has excess meat after a kill (it can't eat all of its prey at once) and is more likely to sacrifice some of that excess to the monkey then risk the monkey trying to get it killed. The monkey feels safe to draw this attention because nothing on the ground is a threat to it while it is in the trees, and it doesn't have larger tree-based predators it's afraid of drawing the attention of.

I'm wondering if this could evolve and work on a partially instinctual level. That is to say none of these species is sapient or capable of advanced reasoning skills, though some of the behaviors could be taught by parents it should still be mostly habitual by now. Blackmail is simply an instinctual part of the monkeys means of collecting food, and the cat simply knows that if he doesn't feed the monkey something bad will happen when it shows up, without the monkey having to explain it's threat...

I'm wondering if such a species could exist in the wild, and if so how it would evolve in the first place (there is a chicken and the egg problem with such complex behaviors becoming habitual, how do each of the three species, monkey, cat, and larger predator, evolve a habitual understand of what the monkey is doing well enough to play its part?)

My current thought is that originally the monkey evolved a symbiotic relationship with the larger predator, to help it find and secure kills, in exchange for getting first dibs on the predator's 'left-overs'. Eventually the cats, having evolved a fear of monkeys due to their bringing predators to attack them, evolved the instinct to 'bribe' the monkey to shut it up. The monkey got his food at less cost then chasing the cat around waiting for a predator to kill it, and so accepts the bribe, and eventually food from bribes became their primary source rather then food after helping the predator secure a kill. Still, I'm not sure if this can be an evolutionary stable dynamic?

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    $\begingroup$ Just in case anyone makes the same mistake I did, I believe this question is about a tree-dwelling animal species, not a highly-evolved form of plant life. $\endgroup$ – DoctorDestructo Feb 2 '17 at 23:02
  • $\begingroup$ @DoctorDestructo Me too. Title edited. $\endgroup$ – Ben Sutton Feb 2 '17 at 23:27
  • $\begingroup$ Wierder things have happened - facebook.com/Historical.Honeybee.Articles/videos/… $\endgroup$ – KalleMP Feb 3 '17 at 6:23
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This actually sounds like something a monkey might do. Monkeys have been known to steal things and not give them back until bribed with food. All it takes is one innovative monkey, or a monkey that stumbles into this situation for it to become an established habit. Primates will teach each other, so if one monkey like species finds this to be an effective strategy then it will quickly spread. Primates can even learn the concept of money and target / steal money.

The most likely scenario I can imagine is this "monkey" species as scavengers that stalk the "lynx" waiting to either gather in numbers high enough to steal the food or just wait until the lynx leaves. One clever or just lucky "monkey" realizes that if it makes enough noise the lynx will be driven off by a higher order predator, leaving the food. Noise => Food. The lynx would likely form sympathetic habits of either eating quickly, or allowing the "monkey" to steal some of the food to prevent the noise.

Further elucidation in response to comments:

This type of complex social relationship would require an amount of social cognizance not typical in most animals. This type of intelligence would likely be on the level of primates, corvids, elephants, dolphins, pigs, and border collies.

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    $\begingroup$ Basically this can arise if both species are capable of social evolution and passing down complex learned behaviours. This does not require the species are particularly social, many solitary predators have a long period of learning skills from their parent before becoming solitary adults. (Added as comment since not enough new to make a separate answer of value.) $\endgroup$ – Ville Niemi Feb 2 '17 at 17:34
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    $\begingroup$ Following on to @Ville comment: I agree with this answer if we assume a sufficiently cognizant cat. For this to be stable, the cat has to learn the value of feeding the monkey... it has to be smart enough to look ahead and see the advantage of giving away food now for lack of abuse later. Doesn't work on dumb cats. $\endgroup$ – SRM Feb 2 '17 at 18:40
  • $\begingroup$ I think I made these assumptions, but failed to enumerate them. Thanks for the comments. $\endgroup$ – user2259716 Feb 2 '17 at 19:04
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    $\begingroup$ Natural selection could do this - those who realize that their giving the monkey meat allows them to survive could teach their children. Also, monkeys are known to develop complex intraspecies social relationships, so bribery could be developed in theory. $\endgroup$ – detrivore Feb 2 '17 at 23:39
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    $\begingroup$ Although not exactly the same behaviour as the one you are describing, the Honeyguide is a bird that has a relationship between itself and other animals, including humans. It makes calls that allow other animals to track it to nests of bees and in the case of people they harvest the honey and the bird picks through the combs leftover for grubs etc. They also have a relationship with the honey badger This clip might be of interest to you.m.youtube.com/watch?v=mVtSYRmlirg $\endgroup$ – Sarriesfan Feb 3 '17 at 14:09
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You're coming at it from the wrong direction. Everyone has to adapt.

First, it's the predator which kills the lynx that has to adapt. This predator learns that the particular sound that the monkeys make means that there is a vulnerable lynx in that location with a fresh kill. Monkeys already instinctively call and have a a language for specific things. Once the predator learns that--the lynx will learn, likely accidently, that they better find a way to shut up the monkeys.

One lynx or a few can learn this and pass it on to their offspring. This will be a learned behavior, not a matter of evolution. However, all the ones that don't learn it, are more likely die, so any stupid lynx that cannot, will be eliminated from the gene pool. So the behavior might not be instinctual or genetic, but the smarts to learn it WILL be.

Now, the other problem is this: the higher order predator may just kill steal--that is, they may not bother with the lynx at all, and will just eat what they have killed once they are driven off.

The monkeys may be smart enough to know that, so I would allow them a softer call at first--letting the lynx know they are there and want their take, but not so loud (yet) as to call the higher order predator. Also, if the kill isn't large, one monkey may not want to share with the others. You have the problem of, if one monkey is satisfied and there are like 50 in the trees, or even a dozen, even a large kill might not be enough.

The higher order predator, meanwhile, has taught their offspring to listen for the call, even if it is faint, because it means food.

One of two things will happen--either the higher-level predator will adapt to the new bribery system and still be able to find the lynx in this way (albeit a little later) OR the higher level predator will forget the meaning of the call at all. Meanwhile, the lynx may still be teaching their offspring this behavior, even though it doesn't have an advantage. Eventually, the behavior of the lynx, of giving the bribe, may actually fade away, unless the higher-order predator still uses the low call from the monkeys to hunt. Whether it is genetic or learned, if there's not advantage or edge to the bribery behavior for the lynx, eventually they might not engage in that behavior any more.

You do want to look at the higher-order predator and THEIR response to this, because that informs how all the others will adapt.

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So, I think this is a cool idea. To make it simpler, let's scale down the question a bit, because you're asking if it "can be an evolutionary stable dynamic."

Let's have a plant and an ant. The ant colony hunts Red Mites, and as such, they gain a red pigment as well. This, unfortunately, has the effect of giving their position away. Through chance, the ants stash part of their Red Mite supplies in a pitcher-plant style plant. This plant, digesting the mites, also gains a red coloring. Ants learn that it's safe to congregate on the red plant, and the plants that are red are the plants that they store mites in, and if they can learn how to avoid being eaten themselves (or, at least, only lose acceptable casualties) they can become co-dependent.

Now, this is way simpler than your question, but the solution comes out to be very similar: you could say the pitcher plant is "demanding a bribe" from the ants; because if the ants stop feeding it red mites, it's color is going to return to normal. The ants don't know what's going on; there's no intentional communication going on here. But, yes, this could end up being evolutionarliy stable. Perhaps the plant becomes more reddish by default, to allow the ants more leeway in it's bribes. Or maybe the best adaptation is to gain a blueish, or some other contrasting, color, which makes the ants even MORE visible to predators unless they keep the pitcher plant fed and, therefore, colored.

So we know it's viable. How about higher level creatures, like your monkey, cat, and tree?

So, let's actually make it a monkey, squirrel, and tree. The predator is the cat. Cats can access trees, and they prey on squirrels. These monkeys, being bigger and more adapted to trees, can easily evade the cats, while the squirrels, who must spend a lot of time on the ground and lower branches of the tree, are preyed upon.

The squirrels are well known for collecting tons of food. They eat acorns which fall from this species of tree. They are well adapted to it, but the monkeys are not. They generally eat fruits from nearby trees.

So how does the bribe work in? Well, say this acorn contains a small amount of THC, nicotine, or some other chemical that the monkeys enjoy. It has no effect on the squirrels (they process it just fine), but it makes monkeys happy. They, therefore, want to steal acorns from the squirrels. Not really being adapted to the land, they don't want to leave the trees. The acorns aren't really ripe and ready for the monkey until they've been on the ground for a few weeks.

The squirrel, of course, doesn't want to give up it's acorns. So the monkeys, suffering from acorn withdrawl, start calling the cat. The cats learn that when the monkeys are behaving in a specific way, squirrels are nearby, and they start hunting the squirrels.

Through natural selection or by accident, the squirrel ends up giving the monkeys some acorns, and amazingly enough, the monkeys chill out and stop making noise. The cats have optimized to hunt in areas where the monkeys are misbehaving, so keeping the monkeys happy is a good survival strategy for the squirrels. They collect acorns, select the best ones for the monkeys, and hand them off, turning off the monkeys, who leave them alone.

This can become an even better deal for the squirrel, because the monkeys learn that protecting the squirrels also protects their source of acorns. So not only do they NOT misbehave and catch the cat's attentions, but they use their higher vantage point to scope out cats in the area, and either warn the squirrel, or scare off the cat (a few well placed pinecones should do it).

Yes, I just turned squirrels into drug dealers, and the monkeys into the mob. But this ends up being the bribing situation you wanted. If the squirrels don't "pay up," the monkeys will assist the cat to hunt them; if the squirrels pay the protection money, the monkeys may actually assist the squirrel. The monkeys get the acorns they want and the squirrel gets to avoid being lunch. Sounds like a pretty good strategy for both.

A completely unrelated comic.

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    $\begingroup$ I think you deserve an extra point just for the comic $\endgroup$ – Samwise Feb 4 '17 at 1:05
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Creatures with sufficient cognitive ability could develop this type of codependency through a variety of cause-effect mechanisms (mostly likely accidental and/or forced in the right direction by environment variables). As mentioned in other answers, primates can be "taught" the concept of money and bribe etc by environmental factors. For example, any setup that results in the "cat" seeing the causal relationship between fully eating their food (which is one way to make an "offering") and arrival of predators would eventually teach them (by natural selection, if nothing else).

But let's say we are talking about species with zero or nominal intelligence (plants without brains and animals/insects working purely on instincts), which is also more interesting and "evolutionary". Here is one solution -

  1. Let's say that we have the following setup -
    • A carnivorous pitcher plant (the ones that look like an open pitcher in which a prey would fall into) that blooms brightly colored/fragranced flowers to attract/trap other insects/animals when the plant is hungry. It's big and tall enough to allow an ecosystem of other animals.
    • Bees that are attracted to the flowers bloomed on the pitcher plant.
    • Koalas that eat those Bees and tend to be around wherever Bees usually congregate.
    • Cats similar to the Cat in your example living on the trees. Initially it doesn't know or care about the plant.
    • Bears that prey on of Koala. They would normally prefer to eat only Koala but could opportunistically also eat the Cats if any are around.

So, to summarize - Plant creates flowers when hungry -> Bees eat flowers -> Koala eat Bees -> Bears eat Koala and Cat.

Finally, let's consider a few mechanisms for the Cats to "offer" the food -

  • Some Cats are prone to accidentally dropping little pieces of their foods as they eat them and these pieces fall into the pitcher.
  • Or alternatively, the Cats catch bigger animals that they can eat at a time and tend to leave leftovers that drop into the pitchers.
  • Or, placing the kills in the pitchers result in the food to become pre-digested or better tasting or something; this means the Cats are actually rewarded for "offering" their kills for a few hours before retrieving it
    All would work but going with the first one one for this example.

Now, in this setup, if the Cats don't drop any pieces of food in the pitcher, the plant blooms flowers which in turn attract Bees which in turn attract Koala which in turns attracts the Bear which also threatens the Cats. If the Cats drop pieces of food, the plant doesn't bloom and doesn't attract anything. Over a long period of time, natural selection will do its thing and only those groups of Cats will survive that instinctively drop pieces of their food (or, in other words, "offer some of their food"). With some environmental nudge, the actual expression of the behavior of "dropping pieces of the food" may evolve to look like an actual offering being made (as we humans understand the concept of offerings). Eventually even the Bears may learn to respond to the blooming and skip the intermediaries - Koalas and Birds.

The cool part about this solution is that neither the plants nor cats is consciously aware of all this (at least initially), it's all driven by natural selection.

We can have a lot of fun tweaking this solution, for example -

  1. How to make the plant ask for a specific offering - we can say that the plant starts blooming when it "smells" the pheromones of a rabbit (because, let's say rabbit pheromones have a chemical structure similar to some enzyme or whatever prerequisite for blooming). It stops blooming if it gets to eat a rabbit. Now, seemingly amazingly, evolution is going to teach the Cats to make offerings of rabbits whenever rabbits are around.

  2. How to make the plant to "call" predators in a more fantastical way - Let's say the predators (Bears) can't get to the Cats because Cats live very high up. Now we can claim that the when the plant doesn't get a specific protein (that can be obtained only from the offerings), its branches droop down (or result in aerial prop roots like that of a Banyan tree) making it climbable by the Bears. Now, it'd look to the outsiders that when Cats stop making offerings, the tree creates a way for Bears to climb

The possibilities are endless...

UPDATE: I realized that the question doesn't ask for a plant that forces an animal into offering food. Here is a solution for that version - Let's just add monkeys (zero intelligence animals unlike the ones in our world) to the plant in my previous setup and make the tree non-carnivore. Let's also say that if monkeys don't find better food, they start attacking the plant's unbloomed flowers which results in a mess that attracts a certain type of bees which eventually attract bears that threaten the cats. If the cats "offer" some of their food, the monkeys stay satiated and don't mess with the flowers. Its the same setup, the tree is still signaling the predator but now monkeys are interacting with the tree a certain way when they don't get food offered.

The above process still works without any of the party to be too smart. I think I've a bunch of variations of this in my mind, I'll probably replace the whole previous "intelligent tree" answer with this one if I get time.

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First the cats eat monkeys whenever they get the chance.

The monkeys are smart and cautious and develop strategies like having their lookouts follow any cat around being loud. Cats try to avoid the monkeys and find sufficient other prey, but they still are bothered by losing days to monkey harassment.

Eventually a cat does something which distracts the monkey following it. Say digging up a new monkey food source or scaring off something defending one. It still can't get at the monkeys because there are almost certainly other lookouts about, but it can now get on with hunting other stuff in peace.

If the cat learns to do the distraction the behavior might be self reinforcing from both sides. The monkeys who associate the cat with the new food will follow and get food unavailable to the others, the cats with the distraction behavior don't get starved by monkey harassment. Even if the two species change to no longer have a predator-prey relationship at all the blackmail might last.

Of course the monkeys gaining behavior to entice the cats to them would be expected to happen sooner or later and that really would break the blackmail down to a simple trade.

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This seems like a very similar concept to the African drongo. (https://en.m.wikipedia.org/wiki/Fork-tailed_drongo)

This little bird mimics the meerkat in order to steal food. It starts off by correctly alerting the meerkats to approaching predators. However its end game is to falsely alert them and then take its pick of the food which the meerkat has obtained. You could use a very similar thing where the two species have a more symbiotic relationship. Essentially your tree dwelling species evolves as a warning bell to help the land based animal. If it is not kept adequately fed it ceases to help. The land animal dies a grizzley death at the hands of some fearsome predator. This is not direct blackmail but it is a reasonable adaptation you could see happen. Tree dweller gets fed and so carrys on its genes.

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One of the problems with blackmail is that it requires high level mental processes to process, both as blackmailer and victim. The other is that the victims sooner or later work out that "if ever you pay the Dangeld, you will never be rid of the Dane". It is an unstable social arrangement, not a stable one. War will replace payment.

So I don't think this relationship can exist purely by evolution. It requires intelligence approaching the human level, at which point evolution has given way to society.

There are quite a few cases where one species leads another species to prey, for mutual benefit. The bee-eater bird has a call that it only ever uses to communicate with people, who it leads to a bee nest. The people break it open to take the honey and the bird gets the leftovers.

I can certainly imagine something like this bird co-evolving with the prey. Maybe in the future there will be bees that feed bee-eaters like aphids feed ants, so the bird doesn't need to call humans in to destroy the nest, and instead protects "its" bees against other bee-eaters and small predator species. But in hard times if the bees cannot keep the bird adequately fed, it will switch to calling humans. This would look like blackmail, but would be missing mental calculation by the bees and communication of an ultimatum by the bird.

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  • $\begingroup$ This instability claim is only true if there is a way to go to war. Given that the "cat" species in the question cannot climb trees, the "monkey" is safe from retribution. Blackmail is stable when there's no way around it. See "water empire". en.wikipedia.org/wiki/Hydraulic_empire Although a lot of the archeology around these in ancient times is in question, there are some well documented ones more recently... they''re notoriously hard to rebel against, much like this blackmail scenario, because the rebellion needs help from the oppressors! $\endgroup$ – SRM Feb 5 '17 at 7:38
  • $\begingroup$ @SRM what am I missing? Seems to me a hydraulic empire has two parties: those who control the water monopoly and those who pay for it. Also, just one species, and sapience. $\endgroup$ – nigel222 Feb 5 '17 at 12:15
  • $\begingroup$ @SRM I can see co-evolution leading the cats to adopt a strategy that keeps the monkeys quiet by sharing their kills. But expanding this to monkeys actively threatening to fetch the cat-predators surely requires sapience. I'd expect evolution to arrive at mutual benefit instead: cats feeding monkeys and monkeys warning cats if the cat-predators approach. This is a positive-sum game with an obvious stable equilibrium. $\endgroup$ – nigel222 Feb 5 '17 at 12:28
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    $\begingroup$ I agree it is unlikely to appear in nature. BUT... if it DID appear in nature, you argued it was unstable. I'm saying that's where I think you have a flaw in your logic. The hydraulic empire was a metaphor to show a blackmail situation that is stable. Under that analogy, if the cat-predator cannot threaten the monkey-blackmailer, it's totally stable. Therefore, if you have sufficient sentience that somehow this pattern arises, I don't see the cats breaking it, barring some serious tech innovation. $\endgroup$ – SRM Feb 5 '17 at 14:02

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