Paradox of Animal Sociality, - Clark University



Paradox of Animal Sociality,

Lecture #2003-11

THE PARADOX OF ANIMAL SOCIALITY: CAN A NEARLY WELL FORMED DARWINIAN STORY BE TOLD ABOUT ALTRUISM?

A.   Introduction

Some behaviors are easier to tell nearly well formed Darwinian stories about than others. An example of a behavior difficult to tell such a story about is the helping behavior of paper wasps.

Around the old sheds of my farm is a wasp, Polistes, who makes its living in the summer by capturing caterpillars off my cabbage plants. Polistes pursues the following rather odd reproductive cycle. The females are mated in the fall and winter over in crevices in buildings. These females begin to emerge as soon as the weather gets warm in the spring and make their way to the my sheds where each female begins to build a nest. At that time, remember, each is a fully functional reproductive. If she continued to build her nest and if it were to be successful, then all the offspring of that nest would be hers.

Then a bizarre thing happens. Some of the females -- perhaps even most of them -- leave their own nests and join other females on their nests and begin to help them raise their broods. In so doing they give up the possibility of ever reproducing themselves. In working on the other female's nest, they subordinate themselves, and this subordination produces a physiological regression. For whatever reason, in only a few days, the fertilized ovaries of these females begin to shrink and eventually these once fully functional reproductive females become “auxiliaries” -- non-reproductive workers that serve the reproduction of other females.

Now, we have no difficulty in seeing how this behavior is useful to the helped female. When one female works alone at the nest, she has to leave it unguarded when she goes off to forage for building materials and food. The nests of single females are thus left vulnerable to predation or plundering of building materials by other species or by other Polistes. The second female is thus a tremendous help in that she can go off and do the foraging, while the reproductive female stays home and does the building and guards the nest and begins to lay eggs. This arrangement is surely one that leads to the production of more wasps. Without working together, the wasps could produce at most a few young each. Working together, the auxiliaries give up the few young they would have produced, but because of this sacrifice, the foundress produces dozens of young. Overall, it seems like a very sensible arrangement.

However, figuring out how a behavior might be sensible is not the same as figuring out how natural selection might bring it about. To explain how natural selection might have produced and maintained a behavior, we have to show how that behavior resulted in the production of more wasps with that behavior. There lies the problem: the wasps, which display the behavior, don't have any offspring. They are too busy helping to raise the offspring of wasps who don’t display the behavior! How then, has the behavior been produced and maintained in the population?

Behavior like that of Polistes has been termed altruistic. We will spend much of this lecture trying to get a handle on this controversial term. For the moment, we can understand that it is behavior that provides benefits to a competitor at a cost to the to the individual performing the behavior. Benefits, you will recall, are always reproductive benefits.

Lets put the puzzle in a more general form. Lets imagine that in a social organization there are Donors and Beneficiaries. Lets further imagine that Donors give to beneficiaries some of their reproductive output. They might accomplish this generosity in a variety of ways, some extreme, some subtle. In the extreme case, they might submit to cannibalism. More subtly, they might not fight so hard to defend their own territory against the territory of a fellow species member, so that their offspring ended up with less food than their neighbors as a consequence. The mechanism is really irrelevant. All that is necessary is that Donorship is an inherited trait and that Donors, as a group, are at a reproductive disadvantage to beneficiaries on account of their donorship. The paradox is, how could donorship be produced and maintained in the population?

Given that (1) a Darwinian story is one that attributes the traits of contemporary animals to the fact that trait bearers have more offspring than non-trait bearers, and given that (2) altruism is defined as a behavior that provides reproductive benefits that lead to the greater reproduction of trait bearers by comparison with non-traitbearers, we can easily see why telling nearly well founded Darwinian stories that explain altruism is difficult. In fact the opposite is true: easily told are Darwinian stories that show that altruism should not evolve and, if it ever did evolve, should be rapidly be replaced by selfish behavior.

B.    Darwinian stories are easy to tell that explain why altruism could never occur.

In the previous lecture, we learned to render Darwinian stories as games tables in which two alternative traits are pitted against one another. In this section, we develop some models that will make clear why it is so difficult to tell well-founded Darwinian stories concerning altruistic behavior. Here is one:

Because hens are highly social animals that have for many generations been selected for the amount and size of the eggs they can produce, they make a useful model for illustrating the paradox of animal sociality. Hens have strict dominance hierarchies and making particularly large and numerous eggs presumably requires the resources that only a particularly dominant hen can obtain. Unless hens are raised alone in individual cages, their egg production is going to depend largely upon their aggressiveness. A hen that can lay many eggs is a hen that can secure more than her share of the food, and such a hen is likely to be an aggressive hen.

Consequently, when hens are selected for individual egg production, flock productivity suffers. The reason is that, while the most aggressive chickens lay the most eggs, the associates of the most aggressive chickens are likely to lay fewer eggs than they would because of the interference from their more aggressive colleagues. Now, imagine a farmer who got to wondering if he wouldn’t get more eggs from his flock as a whole if he selected for less aggressive hens. In order to get this program started, he substitutes a less aggressive breed for half of the chickens in his coop and then measures the productivity of his flock as a whole. To his delight, the chickens suffer fewer injuries and spend less time pecking each other and more time consuming mash and laying eggs. He has fewer "star" hens that individually produce large numbers of eggs, but egg production for the whole flock rises because the "supporting cast" is more productive. However, not being prepared to let matters rest there, the farmer starts selecting his new flock for individual egg-production. An evolutionary games table makes clear what would happen.

| | | |

|Payoff received by |Against individuals playing | |

| | | |

|Individual hens…. …. | | |

| | | | |

| |Nice with probability p |Nasty with probability (1 - p) |Total |

| | | |Payoff |

|Playing | | R | S | |

| | | | |(p)(b-c)+(1-p)(-c)= |

| |Nice |(p)(b-c) |(1-p)(-c) |pb-pc+(-c)-(-pc)= |

| | | | |pb –c |

| | | T | P | |

| |Nasty |p(b) |(1-p)( 0) |( p)(b)+(1-p)( 0)= |

| | | | |pb |

|Nice Hens will come to characterize the population ONLY if the total payoff to Nice Hens is greater than the total payoff to Nasty ones: i.e., |

|when pb-c > pb or when (-c) > 0: i.e., ONLY if the cost is actually a benefit! |

Being nice has both costs and benefits. The benefits might be increased time to spend at eating and laying eggs and fewer injuries: the costs might be less access to food. Thus, the situation bears some resemblance to the table at the end of the previous lecture where we evaluated the circumstances under which an inherited behavior that conveyed both costs and benefits would come to characterize the species. But unlike the situation in the previous chapter where the costs and benefits both accrue to the trait-bearer, in this case, the benefits accrue to both the Nice and the Nasty chickens, while the costs accrue only to the Nice ones. (You can see this if you compare the two tables: notice that while both costs and benefits occur in the upper left cell of the table, only costs occur in the upper right corner where they are experienced by the Nice chickens and only benefits are felt in the lower left cell of the table where they are experienced by Nasty chickens).

Also, if we make just a few assumptions about the sizes of the benefits and the costs, this table becomes a cooperation dilemma table. Recall that a table is a Cooperation Dilemma table if the cells have payoffs in the magnitudes T>R>P>S and 2R (T+S). If we assume that benefits are greater than costs, that benefits are positive and costs are negative, then it follows that (b) > (b-c) > 0 > (-c) and (2[b-c]) ≥ ([b-c]+[b-c]), which meets the conditions for a cooperation dilemma table. So what we have, here, is an evolutionary co-operation dilemma table.

In an evolutionary cooperation dilemma table, since the benefits accrue to both types, they have no effect on their relative fitness and, and the outcome of the game depends entirely on the costs. The totals column shows that the nice chickens will lose ground in the species if there is any cost to the behavior. This rule applies no matter how great the benefits, and no matter how trivial the cost.

The challenge to Darwinism would seem to be profound. If selection for chicken egg production cannot generate nice chickens, how could selection for wasp egg production ever have generated Polistes wasps that help one another to the degree that auxiliary wasps help foundresses? To see what the problem is, lets assume that the foundresses and auxiliaries are distinct genetic types and consider what would happen in a population composed of 50 auxiliary types and 50 foundress types (p = (1 – p) = 50/100). Auxiliary types help other wasps at random, unless they themselves receive an offer of help, in which case they act like foundresses. Foundress types act only as foundresses. Let’s assume, for the purposes of argument, that the population is neither increasing nor decreasing – thus the average reproductive rate across the whole population is 1, including the males (i.e., a reproductive rate of 2 per female). Assume, for the purposes of demonstration, that each auxiliary decreases its own reproductive output by 1 (cost = -1) and increases the reproductive output of the individual it associates with by 2 (benefit = +2. Thus, (b-c) is 1, -c is -1, b is 2, and 0, is, of course 0. Factoring in the relative frequencies of the two types in the population, auxiaries will receive a net benefit of 0 from their interactions with the two other types of individuals, whereas foundresses will be receiving a net benefit of 1, as the table below demonstrates.

|Given that p = 0.5, | | |

|b = +2, c = -1, |…against wasps playing … | |

|payoff received by | | |

|Individual wasps… | | |

| | | | |

| |auxilliary with probability .5 |foundress with probability .5 |Total |

| | | |Payoff |

|Playing | | | | |

| | | | | |

| |auxiliary |(.5)(2-1)=(.5) |(1-.5)(-1)=(-.5) |pb -c=(.5)(2)-1= (0) |

| | | | | |

| |foundress |(.5)(2)=(1) |(1-p)( 0) |pb=(.5)(0) = (1) |

|Assuming that foundresses only build their own nests and auxiliaries, unless they themselves are helped, help other wasps build nests at random, and|

|assume that each helping auxiliary gives a benefit of 2 and incurs a cost of -1 by helping, the nasty will increase by 1 per individual while the |

|nice types stand still [1]. |

Notice that in just one generation, the number of foundress types would increase from 50 percent of the population to 60% (from 50/100 to 150/250) while the auxiliary types would decrease to from 50% of the population to 40% (from 50/100 to 150/250)[2]. This difference would lead eventually to the elimination of the auxiliary type. In fact, as the previous table shows, if being an auxiliary entails any cost, it would lead to elimination of the auxiliary type. How, then, did Polistes come to evolve this social organization? Can we ever tell a "nearly well formed" Darwinian story that will explain such behavior? Or does Darwinism need to be abandoned to accommodate the facts of animal social life.

C.    The role of altruism in Darwinian Stories.

Behavior such as that displayed by Polistes Auxiliaries, behavior that seems to benefit the performer of the behavior less than it benefits others, is often referred to in evolutionary arguments as Altruistic. The basic meaning of altruism is acting against self-interest. Thus, one class of models that are deeply entangled in the paradox is "-interest" models. I put the hyphen before the word interest because the word is coupled with a range of entities, such as "self-interest", "national-interest, "corporate-interest" etc. Such interests are often subdivided. That is, amongst an individual’s "self -interests" we might recognize "health-interests", financial-interests, social interest, etc. The core meaning that appears to unify all these usages is that for each entity before the hyphen in an "-interest" attribution, the attribution identifies some class of events that will make that entity "better off" if a member of that class occurs. So, if we say that it is in the interests of Jones health for him to drink milk every day or get a checkup every year, we are including "drinking milk" and "getting a checkup" amongst the class of events which, if occurs, will be good for Jones's health. Similarly, if we say that it would be in "AT&T's financial interest to obtain Viacom" we would be implying that "obtaining Viacom was amongst a class of events which, if it occurs, would be good for the balance sheet of AT&T. Also implicit in interest attributions is a scale of value by which effects are evaluated. The presence of such scales of value in the argument is often not evident because they are so obvious. For instance, we all assume that a positive effect on the balance sheet of AT&T would be an increase in the amount or dollars represented there.

Even in ordinary language, there is an ambiguity in interest models that can lead to confusion. If we say that it is in Bill Gates's financial interest to obtain Apple, the Bill Gates we imagine after the obtaining is the same Bill Gates we imagine before it. The same would probably true of our imaginings of the proposition that it is in Steve Jobs interest to obtain Microsoft or Microsoft's interest to obtain Apple. However, what of the proposition that it is Apple's interest to obtain Microsoft. Given how such mergers occur and the relative size of the two corporations, could we really imagine that the Apple Corporation that had obtained Microsoft would be the same after the merger? Could we really imagine that, after such a merger, Apple would continue to exist? Thus, the interest starts to break down when we are no longer sure that the entity that has the proposed interest would be the same entity after the interest had been actualized.

The same ambiguity concerning interest models exist in biology. Some such attributions seem uncontroversial. When we assert that it is in the interest of the hawk to catch the mouse (or in the interest of the mouse to escape the hawk), we assert that the hawk that eats the mouse or the mouse that escapes the hawk will be the better for it, but not so much better as to become a different creature. No problems here. However, other interest attributions in biology are much more troublesome. What, for instance, do we imply when we say that it is in the interest of the hawk or the mouse to breed and have offspring? The individual hawk, after breeding and mating, will not be the better for it. In fact, the breeding process is usually dangerous and debilitating. What's more, because of genetic recombination, the products of a breeding process are not the same entity, any more than an Apple that merged with a Microsoft would be the same Apple. So, when we are talking about an animal's mating and breeding, we are talking about a different sort of interest than when we are talking about its having a good meal and a good night's sleep.

Whatever sorts of interest this latter type is, it is the sort of interest that ought to concern a Darwinian. In Darwinism, the essential creative force is the differential reproduction of entities. Surely, therefore, the interest the organism has in courting, mating, and raising young, its "reproductive-interest", if you will, is the only interest that counts. Yet, because of the facts of reproduction, the entity produced is not the same entity as that to which we input the interest.

One solution to this difficulty would be to descend to the genetic level and speak of the interest of the genes for various traits. This is, of course, Dawkins's solution. Thus, altruism would be redefined as acting against the collective interest of one's genes. We might, for instance, say that it is in the interest of the hawk's hunting genes for the hawk to raise offspring, meaning that if the hawk died without bearing young, there would be no such genes. This way of speaking doesn’t raise the difficulty of a change in the entity that has an interest actualized because the "gene for" hunting in the hawk-parent is the same as the gene for hunting in those of its offspring that receive the gene and the offspring-rearing of the hawk helps to spread the hunting gene. To return to our corporate interest model, for moment, this solution would be like saying that a merger between Apple and Microsoft might be in the interest of Apple's stockholders, even though Apple would cease to exist as an entity. Apple stockholders receive Microsoft stock as part of the merger and they might well earn more money on their Microsoft stock than they had been on their Apple stock.

The metaphor seems at first to be promising. Like genes, stockholders are elements of corporations that survive important changes in the corporation. However, to make the metaphor work, we would have to overcome some obvious disanalogies. For stockholders to be like genes, each would have to control some feature of the corporation's structure; say, one stock holder might control the letter head, another type the choice of car in the corporate car fleet, a third the choice of airline flown by the corporations executives when they travel, and so forth. Some stockholders might have a hand in many decisions; others might collaborate to make a single decision. But each stockholder would have a competence that would affect the structure and behavior of the corporation in one or more particular ways.

To make the corporate analogy work, we would also have to reconceptualize a merger. During a merger, each stockholder at Apple that controlled a given feature of the corporation would meet with his equal number at Microsoft, clone themselves a bunch of times, and then they would get distributed to a bunch of new corporations containing different combinations of Microsoft stockholders and the features they control with apple stock holders and the features they control. Thus, for instance, some companies might end up with Microsoft letterhead and Apple automobiles while other of these offspring companies might end up with Apple letterhead and Microsoft fleet of automobiles. These derivative companies would compete and the most productive would get to go on to the next merger.

Now, if we modify the corporate model in this way, what do we conclude about the statement that it would be in the stockholders' interest for Apple to merge with Microsoft? Well, the answer is, not in the interest of ALL stockholders. I think some stockholders would profit from the merger and some would not. Thus, there would be no single "stockholders" interest that the behavior of the corporation represents. Similarly, there is no single "genetic" interest that the behavior of the gene-bearer represents and altruism, therefore, cannot be understood as behavior that opposes -- or advances -- the interests of genes.

For all of these reasons, I conclude that because the concept of "blank-altruism" is rooted in the concept of "blank-interest", it is a concept that is not going to bear much weight. My policy, here, therefore will be to use the concept warily. In the context of this Darwinian argument, an entity (E) will be understood to have a Darwinian E-interest when I can imagine a state of affairs that would the reproduction of that entity. Recall that in this context a benefit is always an increase in reproduction over the competition. The entity could possibly be a gene, an individual, a group or species. I will measure the success at reproduction by counting the relative number of offspring, propogules, copies etc, of that entity that themselves reach reproductive age[3]. Any event that increases this number will be referred to as a benefit to E, any event that decreases this number, a cost.

With this conceptual equipment in place, I can now make a distinction between Darwinian Selfishness and Darwinian Altruism. I will call a trait selfish if is hereditable and governs the actualization of a Darwinian interest in the individual that bears the trait. I will call a trait altruistic when it actualizes the interest of one or more a competing entities and an entity a Darwinian altruist if it has a hereditable trait that governs the actualization of an interest for an entity other than the entity in question. The entity will be judged an altruist whether or not the receiver of the benefit is a relative or otherwise a bearer of the altruist trait. In fact, on this definition, the only other entities to which benefits can be conveyed without altruism are offspring.

Our focus on Darwinian interests does not, of course, preclude the possibility that there are other kinds of interests. For instance, we might speak of the somatic interest of an individual, referring to all the events that might occur or all the things the individual might do that would make that individual fatter, healthier, happier, etc. Very often, of course, somatic interests are in accord with Darwinian ones. But not always. You may have noticed that raising teenaged children (or putting them through college, for that matter) has not seemed to have made your parents fatter, healthier or happier, even though sociological and economic analysis would seem to suggest that it will increase the number of their direct descendants.

The paradox of animal sociality may now be restated as follows. If Darwinian natural selection favors only selfish entities (i.e., entities with selfish traits, or entities that actualize Darwinian interests), why is it that so much behavior is (or appears to be) altruistic?

-----------------------

[1]In case the numbers are bothering you, as well they might, here is how they work. The population started out with 50 “foundress-type” wasps and 50 “auxiliary-type” wasps. Assuming that the population was in balance before the auxiliary type was introduced, females working alone (as foundress types still do) have to be having two offspring, one for herself and one for the male who mated her. For auxiliaries (“cooperators”) their reproductive rate stays at 2, and their total output is therefore 100 wasps; for foundress-types (“defectors”) overall, the rate increases to 3 and their total output is 150 wasps. Thus at the end of one generation there will be 150 foundress-types(60%) and 100 (40%) auxiliary types.

[2] OK. I can hear my readers screaming, what about a trait that made sacrifices in the number of children to favor the number of grandchildren. Wouldn’t that be in the Darwinian interest of the trait-bearer. I agree. So a Darwinian interest actually refers iteratively to the number of descendants in the direct pedigree of the traitbearer. For most purposes, this number is fairly represented by the number of offspring. Not always, though, as we shall seen in the next lecture.

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