The Bowerbirds and the Bees: Miller on Art, Altruism and Sexual Selection. Catherine Driscoll* Dept. of Philosophy. North Carolina State University

Transcription

1 Miller on Art, Altruism and Sexual Selection 1 The Bowerbirds and the Bees: Miller on Art, Altruism and Sexual Selection Catherine Driscoll* Dept. of Philosophy North Carolina State University *Many thanks to Stephen Stich and Walter Sinnott-Armstrong for many comments on earlier drafts of this paper; and to Iris Oved and the participants in the Rutgers graduate seminar on the Evolution of Cognition for their feedback on some earlier versions of ideas I discuss here. Address for correspondence: Department of Philosophy, North Carolina State University, Campus Box 8103, Raleigh NC catherinedriscol@hotmail.com

2 Miller on Art, Altruism and Sexual Selection 2 The Bowerbirds and the Bees: Miller on Art, Altruism and Sexual Selection Abstract Geoffrey Miller argues that we can account for the evolution of human art and altruism via the action of sexual selection. He identifies five characteristics supposedly unique to sexual adaptations: fitness indicating cost; involvement in courtship; heritability; variability and sexual differentiation. Miller claims that art and altruism possess these characteristics. I argue that not only does he not demonstrate that art and altruism possess these characteristics; one can also explain the origins of altruism via a form of group selection and traits with the five characteristics in terms of a process I call cultural sexual selection.

3 Miller on Art, Altruism and Sexual Selection 3 The Bowerbirds and the Bees: Miller on Art, Altruism and Sexual Selection 1. Introduction Explanations of the origins of human psychological and behavioral traits in terms of sexual selection have not been very common in the evolutionary behavioral sciences. Sexual selection is a process by which the sexual choice of individuals and/or the competition between individuals for mates drives the evolution of characters within a population. The question Geoffrey Miller addresses in his book "the Mating Mind" (2000) is whether such a process could account for some of the elements of "human nature" that have eluded other kinds of evolutionary explanations up to this point. Miller believes that human psychological mechanisms for producing art and/or artistic behavior are very good candidates to be sexual adaptations (i.e. traits present in a population because of the action of sexual selection); he believes the same is true for the more extreme forms of human altruism 1 - in particular those that involve making grand and wasteful altruistic gestures that are not easily explained using standard models of reciprocal altruism 2 and kin 1 The biological definition of an altruistic act is an act "where an animal behaves in such a way as to promote the advantages of other members of its species not its direct descendents at the expense of its own" (Hamilton, 1963) - i.e. altruistic acts involve taking fitness costs for oneself as a consequence of acting to benefit other member(s) of one's species. 2 Reciprocal altruism can be explained as follows: if the participants in any trade of costs and benefits are going to meet more than once, and if the interaction will lead to greater benefits to the recipient than costs to the donor (i.e. if the interaction is non-zero sum), then reciprocal altruism can evolve. If a participant's involvement in any given interaction is dependant on having received cooperation from the other participant in their previous interaction, then altruists who pay back the benefits they have derived from previous interactions are more fit than selfish individuals who do not. The selfish individuals are rapidly excluded from the benefits of altruistic interaction since they do not reciprocate, while altruists can continue to benefit. This is because they receive more benefit overall from engaging

4 Miller on Art, Altruism and Sexual Selection 4 selection 3 (nepotistic altruism). There are five main characteristics of sexually selected traits that are more or less unique to such traits. Miller claims that art and altruism show many or all of these characteristics, and are therefore likely to be sexual adaptations. My thesis in this paper is that Miller s case for the origin of these two traits via sexual selection, although original, is problematic. Miller s argument faces a variety of different problems, and these fall into three main classes. First, there is the problem of what kinds of traits he has in mind by art and altruism are these psychological capacities that humans possess, or certain types of behavior in which human beings engage, or indeed the products of artistic activity(e.g. paintings, sculptures, etc.) as the extended phenotypes of the artist? Second, it is not clear that art and altruism possess the five characteristics that Miller thinks identify sexually selected traits. Third, Miller s argument relies on there being no other process that could explain the presence of the five characteristics as well as sexual selection, but there is at least one cultural process that can also reliably generate traits with those characteristics. Finally, it appears from the literature that there is a much better explanation for the origin of altruistic behavior than sexual selection. In this paper I will proceed as follows. In Section 2 I describe the process of sexual selection. Section 3 will describe Miller s argument, including the five main characteristics that identify sexually selected traits. Then in Section 4 I will present the problems relating to Miller s definition of art and altruism. Section 5 attacks Miller s claim that art and altruism possess in reciprocal interactions than selfish individuals who cannot. 3 Kin selection occurs where genes for assisting relatives tend to increase themselves - close relatives of an organism that possesses a gene for helping relatives are likely to possess copies of the same genes. Thus an organism O that possess a gene for helping relatives G will tend to increase the survival or reproduction of other copies of G in the O's relatives.

5 Miller on Art, Altruism and Sexual Selection 5 the five characteristics. Section 6 will discuss an important alternative explanation for altruism and offer reasons for thinking this account is better than Miller s; in Section 7 I will present an alternative explanation for the origins of traits with Miller s five characteristics in terms of cultural evolution. 2. What is sexual selection? Sexual selection is often invoked to explain traits that arise in nature that are strange, extreme or otherwise costly to the organism that possesses them. Sexual selection is a process by which sexual choice or competition for mates among individual animals leads to certain traits increasing in the population; i.e. those traits which make the individuals that possess them more likely to win sexual competitions or to be preferred by members of the opposite sex. Sexual selection's most interesting characteristic is that it can cause a trait T to evolve even where T is otherwise not very fit - i.e. beyond its assistance in the competition for sexual opportunities, T does not help or even inhibits an animal's survival and reproduction. Thus sexual selection is often implicated in the evolution of big, showy, extravagant traits that seem as though they ought to reduce the fitness of the organism that possesses them. An example of such a trait would be the peacock's tail - it is big and showy, and it makes the peacock both more visible to predators and less agile and able to escape those predators. However, peahens like the tail; and this preference drives the tail's evolution. Sexual selection comes in two main forms: sexual selection by competition for mates and sexual selection by (usually female) choice. I will describe these two, and then explain how the process of runaway sexual selection can drive traits to surprising extremes.

6 Miller on Art, Altruism and Sexual Selection Sexual selection by competition Sexual selection by competition occurs in species where members of one sex compete among themselves for access to the other (usually males compete for females). Males that possess traits which allow them to win the sexual competition against other males gain access to more females or to fitter, healthier females than those that do not have these traits; they then pass on these successful traits to their (more numerous or healthier, more likely to survive) offspring. This can lead to these traits increasing in frequency in the population. A classic example would be the competitions between male red deer, who battle each other using their antlers. The winners of these battles usually the strongest males - gain mating access to herds of females Sexual selection by mate choice Sexual competition by mate choice occurs where the members of one sex choose mates from among the members of the opposite sex. Because females bear the greater part of the burden of reproductive investment they generally are the ones that choose which males to mate with. In species where there is monogamy, males may also choose which females to pair up with; this can lead to some sexual selection on females as well. Usually these choices take place on the basis of the female's preference for some male trait T; males with T will gain greater access to females than males without T. Therefore T will increase in prevalence in the population Feedback loops and "runaway sexual selection" The way in which sexual selection has the potential to produce the strange evolutionary phenomena I described earlier is via the phenomena of runaway sexual selection. Runaway sexual selection occurs because there is, in effect, a feedback loop between male traits and

7 Miller on Art, Altruism and Sexual Selection 7 female preferences. The phenomenon of runaway sexual selection was described by R. A. Fisher (1930). His point was that sexual preferences are self-reinforcing, because when a female has a preference for a certain male trait, and mates preferentially based on that trait, she passes on both that male trait to her sons, and her own preference for that trait to her daughters, thereby increasing both the representation of the trait in the population and the representation of the preference for that trait. This "feedback loop" can make sexual selection proceed very rapidly. Runaway sexual selection has particularly noticeable effects where females prefer a trait that comes in degrees and where they prefer more of that trait to less of it. For example, suppose females like elaborate crests, and the more elaborate the crest the better. Every time a new, more extreme version of the trait arises, females choose males with that variant and the feedback loop drives the new version to fixation very quickly. It is this sort of runaway sexual selection that is likely to be responsible for some of the more extreme traits possessed by male animals - for example, the extremely elaborate plumage of male birds of paradise. So far I have described what sexual selection is supposed to be and some of the ways in which it can operate. I now want to briefly describe a major problem for sexual selection and its potential solution The problem of female choice As I described earlier, it is clear that in many cases sexual selection is acting against natural selection in that females are choosing traits that would, without the sexual preference, be clearly harmful to the males that possessed them - e.g. the peacock's tail. The problem here is that when females choose traits that may have a negative effect on the males that possess them, they pass on those negative traits to their sons; their preferences therefore give their sons a

8 Miller on Art, Altruism and Sexual Selection 8 fitness disadvantage. In other words, one could object that surely female choice is also capable of being the target of natural selection, and if so, extreme female choice must surely be selected against. Females that prefer males with traits which do not threaten the male's well being must have sons that are better off in non-sexual ways (and hence will probably live longer to participate in more sexual competitions). Since the mother also creates a feedback loop by passing on sensible preferences to her daughters, her sons have as much sexual success as those males whose mothers choose extreme traits, and they live longer because they are not burdened with a cumbersome sexual adaptation. Thus sensible female preferences must out-compete extreme female preferences. In other words, if we are to explain why extreme and costly traits arise in nature, we need more than merely ordinary sexual choice to be operating The handicap principle Amotz Zahavi (1975) proposed a solution to the problem of female choice. He claimed there was a way in which females who chose extreme traits in their mates could end up producing fitter sons. The idea is that extreme traits are good indicators of the overall fitness of the male that the female is choosing. Although an extreme trait may itself be detrimental to the male's fitness, he can only produce a complex or extreme trait really well if he is otherwise sufficiently genetically and physically sound. Sickly or genetically inferior males do not produce extreme traits or produce extreme traits that are less spectacular. This means that a female can use the quality of an extreme trait as an index of the male's overall genetic or physical health - and this is especially useful where there is no other way for a female to determine the overall quality of a male. So why do females that choose extreme traits out-compete females that choose sensible

9 Miller on Art, Altruism and Sexual Selection 9 traits? If a female chooses a male who has a superficial trait that is fitter - i.e. it is not extreme and costly - she is, in effect, passing on one positive trait to her sons. If a female chooses a male with a really extreme trait, she is passing on multiple positive traits to her sons, because she is choosing a male who has overall higher genetic quality. Extreme traits may individually have high fitness costs, but they are often good indicators of the overall quality of the male the female is choosing - they are good "fitness indicators". Miller claims that art and altruism have evolved as sexual adaptations in humans, as just these sorts of fitness indicator traits. I will now examine how Miller proposes to support this claim. 3. Miller s argument Miller identifies himself as an evolutionary psychologist. Evolutionary psychologists try to detect adaptations - traits that are present in the population due to the past action of natural selection - by looking for two basic sets of characteristics in the traits which they are interested in accounting for. Generally, evolutionary psychologists look for good design in psychological mechanisms (Cosmides and Tooby 1987, Tooby and Cosmides 1992). When they find good design in a trait T, evolutionary psychologists will argue that they have good evidence that T is an adaptation. The reason is that natural selection is the process most likely by far to produce good design in traits. In other words evolutionary psychologists are making an argument to the best explanation; that natural selection is the best explanation for traits that are optimal or welldesigned. Miller is using a similar sort of strategy in his argument that art and altruism are sexual adaptations. Traits with a certain suite of characteristics are most likely to have been produced by sexual selection; when we find those characteristics in a trait we have some good reason to think

10 Miller on Art, Altruism and Sexual Selection 10 that the trait in question was produced by sexual selection (Miller, 2000, p.132-3). Sexual selection produces different sets of characteristics in the traits it acts upon than does standard natural selection. In his book, Miller identifies five central characteristics that he thinks are unique to sexually selected traits. These are as follows: 1) implication in courtship, since such involvement is necessary if the trait is to be used as a criterion for mating decisions; 2) having a high energy or fitness cost, so that the trait can act as an indicator of overall fitness; 3) high sexual differentiation, since usually a sexually selected trait is used by one sex as a way of deciding between the members of the other sex; 4) having a high degree of variance, allowing the trait to be used as a means of distinguishing between members of a sex; and 5) having a high degree of heritability, so that the possessor reliably passes on the trait to its offspring. Where one can determine that a trait has these characteristics, one has reason to think that the trait in question was produced by sexual selection. Miller s argument is, in essence, that art and altruism in humans possess just these characteristics therefore they are likely to be sexual adaptations. In that case there are clearly two main ways to criticize Miller s argument. First, we can attack his claim that art and altruism really do possess his five characteristics. Second, we can show that there is another process that is equally likely to produce those five characteristics in human behavioral traits. In Sections 5 and 7 I will follow these two lines of attack in turn. First however, we need to decide what kind of traits Miller has in mind when he uses the terms art and altruism. 4. What are Art and Altruism? One of Miller s difficulties in his book is that he is not clear about what exactly his hypothesis is in particular, what kind of adaptations he has in mind by art and altruism.

11 Miller on Art, Altruism and Sexual Selection 11 The sexual adaptations for art and altruism could be some kind of psychological mechanisms that produce art and altruism; they could be artistic or altruistic behavior; or they could be the products of altruistic and artistic behaviors altruistic gifts and works of art. Whatever it is Miller does have in mind behavior, artifact or mechanism it has to be the kind of thing that can actually possess the five identifying characteristics of sexual adaptations. Consider first what Miller might mean by art. In the production of art, on his view, something like the following occurs. First of all, humans possess a suite of sensory-motor capacities, which are involved in both the production of art and in other kinds of behavior. Miller claims that high quality sensory motor skills are likely to be well correlated with fitness and clearly intends these skills to be the fit properties that the artistic sexual adaptation must indicate (p.281). On Miller s view humans also possess some sort of psychological mechanism(s) that give them the desire and motivation to produce art. The interaction of this psychological mechanism with the sensory motor capacities produces artistic behavior. The consequence of artistic behavior is sometimes an independent artwork; sometimes the behavior itself counts as the artwork (e.g. singing, dancing, acting). So is the artistic adaptation the mechanism, the behavior or the artwork? If Miller has in mind the psychological mechanisms for art, then he has a problem, since it is clear that psychological mechanisms per se cannot be used by potential sexual partners as fitness indicators, since they do not vary as a function of the quality of the sensory motor skills that are supposed to be correlates of fitness. Instead, the psychological mechanism interacts with those sensory-motor skills to produce artistic behavior or artworks which do vary in the appropriate way. This leaves us artistic behavior and the artworks themselves as the only possible candidates for sexual adaptations. A similar problem arises in the case of altruism

12 Miller on Art, Altruism and Sexual Selection 12 Miller is not clear whether he is trying to identify a psychological mechanism for altruism, altruistic behavior, or the altruistic gifts themselves. Nor is it clear exactly what beneficial trait or traits Miller thinks are indicated by the altruistic sexual adaptation. One possibility Miller might have in mind is that altruism, some of the time, is the consequence of the interaction of psychological mechanisms for altruism together with, in some cases, practical resources e.g. money, food, etc. - to produce certain sorts of behavior. Since the type and extent of altruistic behavior produced by the mechanism, and the absolute gifts themselves depend on the available resources, altruistic behavior and altruistic gifts will both vary as resources vary. If this is what Miller means, then the fitness property for which altruism is a fitness indicator is really the possession of those resources. Just as in the case of art, a psychological mechanism for altruism is not what is indicating the presence of those resources because it doesn t vary as a function of those resources. Rather, it is the altruistic behavior or gifts that indicate fitness. Hence if the altruistic sexual adaptation is to indicate fitness, then it must either be altruistic behavior, or it must be the altruistic gifts themselves. Consequently, Miller s choices for his artistic and altruistic sexual adaptations are either artistic and altruistic behaviors or artworks and altruistic gifts per se. Miller occasionally suggests that the latter is what he has in mind (Miller, 2000, p.270-1). However, the idea that artworks or gifts are in themselves traits of human beings and, what is more, sexual adaptations, is somewhat strange. The alternative is for Miller to accept that artistic and altruistic behavior is itself a sexual adaptation. This looks like the most plausible of the possible hypotheses available to Miller. However, Miller identifies as an evolutionary psychologist, and as such might want to resist the idea that behavior is the appropriate level of description at which to direct evolutionary explanations, as have others in his field (e.g. Cosmides and Tooby, 1987). I think this would be

13 Miller on Art, Altruism and Sexual Selection 13 a mistake. Either way, Miller needs to be clearer about what exactly his hypothesis is. 5. Do art and altruism have the five characteristics? In order for Miller to make his argument he must offer reasonable evidence that art and altruism do in fact possess his five characteristics. In the sections that follow I am going to argue that there are serious problems with this claim. In particular, I am going to argue that Miller s case is much weaker for altruism than it is for art, and hence an explanation for altruism in terms of some other kind of process might be justified Lack of evidence of courtship involvement in art and altruism It is arguable that of the five characteristics Miller identifies, the involvement in courtship is the most clearly indicative of the activity of sexual selection. If art and showy altruism are sexual adaptations, it must be the case that being a good artist or altruist is likely to allow you to attract more or better sexual partners than those who are not good artists or altruists. This is, I think, the most difficult part of Miller's case; at least partly because when studying humans it is difficult to show that possessing some trait increases a person's sexual success. Miller's main evidence that art is implicated in courtship comes from the natural world; that the closest thing to "artistic" behavior in animals does seem to have a courtship function. His example is the nest building behavior of male bowerbirds. Male bowerbirds build bowers that have no function beyond attracting the attention of females; females mate with males who build the bowers they like the best, and they appear to make these choices on purely aesthetic grounds (Miller, 2000, p ). However, although it might be clear that the "artistic" behavior of bowerbirds has a function in courtship, it is not so clear this is true in humans. Part of the

14 Miller on Art, Altruism and Sexual Selection 14 problem is the sheer difficulty of demonstrating a connection between (good) artistic behavior and sexual success - how would one go about demonstrating that good artists on average do better sexually than bad, or those who are not artistic at all? At best there is anecdotal evidence that individuals find talented artists attractive, and Miller does facetiously refer to the notorious sexual success of Picasso, Gauguin and Modigliani (p.274). Miller does argue that the courtship requirement is not a very challenging criterion; that "it was not necessary for hominids to favor great artists over great hunters or great mothers only for them to favor those who showed taste and talent in their everyday self ornamentation over those who did not, all else being equal" (p.274.) However, body ornamentation is very different from, say, painting or sculpture if we had evidence that body ornamentation was employed in courtship, this would not be clear evidence that the same was or is true of paintings and sculptures. Nevertheless Miller purports to explain the latter as well as the former via sexual selection. Clearly Miller needs to address this problem more carefully. Just as in the case of art, Miller cites examples from the natural world where altruism is used as a form of courtship display; one example he uses is Amotz and Avishag Zahavi's (1997) study of Arabian babblers. These birds live in large groups in which a few of them behave in ways that are conspicuously altruistic. They share food with non-relatives and help with unrelated offspring; they act as sentinels - give alarm calls to warn of approaching predators and mob the predators if they come too close. Since the birds help non-kin, and actually compete rather than avoid the sentinel job, this does not seem to be a case of either reciprocal altruism or kin selection. What is more, only birds that are very fit and in good condition are able to take over this role - Zahavi believes that the altruism is a form of sexual display employing the handicap principle. Is altruism amongst humans the same?

15 Miller on Art, Altruism and Sexual Selection 15 Miller uses evidence regarding the hunting behavior of men in foraging societies to claim that altruism may be used in courtship in humans (Miller, 2000, p ). In these societies men usually spend their days hunting. Their behavior seems odd for several reasons. First, men usually spend most of their time going after really big game that are hard to catch and unreliable sources of food. Second, men using this method have a (sometimes much less than) 10% chance of bringing home food each day. Third, when men are successful and bring something home, they tend to share the food with the whole tribe. The reason for this behavior might be some sort of reciprocal exchange of food, since if everyone eats whenever a man catches something, everyone eats some meat more often and the meat supply is more stable. In practice this is not how it works, since reciprocity depends on men being equally good hunters; for reciprocity to work, one person has to be able to pay the other back as much as was given, but where hunting ability varies considerably this cannot be the case. A poor hunter cannot reciprocate properly with a good hunter. And in fact, men do vary in their hunting ability (see Kristen Hawke s (1993) discussion of the hunting practices of men in hunter-gatherer societies). Miller claims that these successful hunters are in fact making a sexual display; they feed everyone in a costly way and they are able to have more or better sexual partners as a consequence. Miller argues that this pattern of sexual display may have evolved partly by group selection, since groups with this practice do better than groups with other sexual selection practices. The problem with this example is that although altruistic sharing is involved in this case, it seems that altruism is indicating hunting ability and hence it is not clear whether this is evidence of how extreme altruism might have evolved in cases where altruism has to indicate something other than hunting. Miller also cites David Buss's (1990) study of sex preferences across 37 cultures, where

16 Miller on Art, Altruism and Sexual Selection 16 "kindness" was the single most important feature desired in a sex partner by both men and women in every culture; more important than beauty, intelligence and status. Miller takes this as evidence that altruism is a trait that is sexually desirable across cultures (Miller, 2000 p.292). If individuals really do look for altruism when choosing a partner, then there may be some reason to think that individuals might want to flaunt altruism during courtship. While this may be good evidence that kindness is a trait that is used in courtship display, it is not clear that the kindness referred to on Buss s study is altruism in the biological sense engaging in behavior that involves taking on a fitness cost for others. Nor is it obviously the extreme, showy altruism that Miller wants to explain Does artistic behavior act as a fitness indicator? As well as having problems with how art fits the courtship involvement criterion for being a sexual adaptation, Miller also needs to account for the serious problem about how far real artistic behavior acts as a fitness indicator. As I explained in Section 4, the most obvious way to understand Miller s hypothesis that art is a sexual adaptation is to take artistic behavior or artworks to be fitness indicators for underlying sensory-motor capacities. Miller thinks the fitness indication of artistic behavior is to be found in the nature of the psychological, perceptual and physiological capacities necessary to produce good artistic behavior. He argues that human aesthetic preferences find most beautiful those things that are most demanding on the producer - that require large quantities of "health, endurance, hand-eye co-ordination, fine motor control, intelligence, creativity, access to rare materials, the ability to learn difficult skills and lots of free time (p.281). He goes on to argue that there is evidence that creativity is well correlated with intelligence; and that it may have other kinds of fitness value (p.409).

17 Miller on Art, Altruism and Sexual Selection 17 This is all very well clearly artistic behavior could act as an indicator trait. However, Miller now has a new problem. Quite a lot of real artistic behavior, especially within the modern avant-garde, is not meant to be a show of beauty and/or technical skill (except perhaps intelligence and creativity). In fact, the point of certain forms of art (for example, DaDaism) is to flout human beings conceptions of what aesthetically pleasing things ought to be like. If so, how can this kind of artistic behavior are accounted for as a sexually selected indicator trait? Miller tries to get around this problem by making a distinction between the kinds of art he is trying to explain (simpler early forms of ornamentation, representation, singing, etc,) and the art produced as a consequence of modern cultural institutions. Miller claims that the rise of conceptual and avant-garde art is permitted by the presence of cultural institutions for art that permit forms of artistic production and behaviors that are not entirely connected to the original adaptations for producing and judging works of art. Being part of an artistic institution now confers status, especially on insiders who "understand" new forms of art (p.284-5). I take it that Miller means that artistic behavior produced by many of those participating in these institutions is a cultural rather than a biological phenomenon, though one that borrows from human beings biological heritage; nevertheless it is pursued out of a (biological) desire for high status. Miller claims that this shift away from the original function of artistic behavior as an indicator of fitness is evidenced by the responses of "ordinary folk" to the works of the artistic avant-garde. Their confusion reveals that they are looking for a display of skill on the part of the artist (p.284-5). Miller also thinks that the modern desire for handmade imperfection in objects rather than mass-produced perfection is evidence of the fact that human beings are looking for works that really express human skill (p.286-8). This explanation, however, does weaken his argument since it is a concession that not all art can be explained by the sexual selection

18 Miller on Art, Altruism and Sexual Selection 18 hypothesis The reality of sexual differentiation in art Another area where Miller has serious trouble making his case is in regard to the sexual differentiation in the traits he is studying, particularly in the case of art. Do only men have sexual adaptations to produce artistic behavior, or at least stronger adaptations to produce artistic behavior than women do? Up to the present century, with its new freedoms for women - but also its development of new and complex artistic institutions - men were the main producers of art 4. This might mean that artistic behavior is purely a sexual adaptation in men, and that artistic behavior in women is either a side effect, or the result of cultural changes that encouraged women to involve themselves in artistic institutions; i.e. artistic behavior in women is a cultural rather than a "biological" phenomenon. Or the higher production of art by men might be due to the cultural oppression of women. There are three possible ways for Miller to respond to this piece of evidence without undermining his argument. The first is to accept the sex differentiation, and claim this as evidence that artistic behavior really is a sexual adaptation - for men. Miller, understandably, wants to resist this conclusion, and to argue that women's capacity for artistic behavior is real, whilst still maintaining that artistic behavior is a true sexual adaptation. This is not just because Miller wants impeccable feminist credentials, but also because women do make art now and at least some of the time in the past. It would be very surprising if a costly indicator trait were 4 Of course, this observation may simply be due to a tendency to focus on the forms of art (such as painting, sculpture, classical music, etc.) that were primarily produced by men, rather than the forms of painting and (particularly household) ornamentation produced by women.

19 Miller on Art, Altruism and Sexual Selection 19 maintained in a sex that didn't need it to indicate sexual fitness; if women don't need artistic behavior, it ought to be selected against in women. If artistic behavior continues in women despite its costs, it might suggest that the origin of artistic behavior was as something other than a standard sexual adaptation. This leaves Miller with two possible avenues for argument. First, he can argue that humans are a largely monogamous species, and this meant that in human history males often exercised sexual choice in monogamous relationships, and that they preferred artistically talented women to those women who were not (p.383-6). Hence artistic behavior is a sexual adaptation in women, as it is in men; male predominance in the arts is just a symptom of a patriarchal culture. Second, Miller could argue that artistic behavior as a sexual adaptation requires a two way relationship: producer and consumer (p.375-7). The idea, of course, is that men are the producers of artistic behavior and women are the consumers. If artistic behavior is to work well as an indicator trait, then the consumers of art have to be very good at distinguishing good art from bad; and this will probably require that the consumer have as fine skills of judgment and intelligence as the producer. Miller claims that the producer-critic distinction predicts that men (producers) will make more art; and that women (consumers), when they and were they to make art, would be as good at it as men are. I don't agree that Miller s distinction really predicts this. Miller is right that the consumer producer distinction predicts that consumers and producers must share some of the same capacities in common indeed it seems that visual artists, for example, rely on the similarities between their own perceptual mechanisms and that of their audience to make their point (Cavanagh, 2005). However, creating art requires the individual to have, among other things, fine motor skills and creativity, not just certain perceptual abilities; and if being selected for

20 Miller on Art, Altruism and Sexual Selection 20 being a consumer is to give women the skills to be producers, then being a consumer will have to require exactly the same abilities as being a producer. It does seem strange to suggest that you need fine motor skills and creativity to appreciate art. One possible way Miller could turn out to be right is if appreciating art requires a kind of mental simulation of the task of generating it, so that motor mechanisms that would be used in production were used offline in consumption. Neuro-imaging could show whether the same systems become active in both production and appreciation of art. However, Miller does not provide any evidence of this kind Can altruistic behavior act as a fitness indicator? I think that there is much more serious objection to Miller s claim that altruism meets his second criterion, that of being costly in order to act as an indicator of genetic fitness. Not only does Miller have very little evidence that altruism acts as an indicator trait, he is very unclear about how altruism acts as an indicator. Miller argues that if showy, extravagant altruism (or indeed, any kind of altruism) is to act as a fitness indicator, it should not only be costly, but individuals should take on the cost as publicly as possible, so that potential mates can take note of it. Obviously, altruism by definition involves taking on a fitness cost to oneself in order to benefit others; the question is whether taking on this cost is a way of indicating that one is fit or otherwise in possession of extensive physical and/or genetic resources. Miller argues that in fact, individuals acting altruistically are more interested in the cost of an altruistic act than they are in its positive consequences; just as they should be if they were interested in making a display rather than engaging in a nepotistic or reciprocally altruistic interaction. He uses as his examples the lack of interest that individuals show in the efficiency of the charities to which they contribute (p.324). Miller also thinks that wealthy individuals who work in soup kitchens instead

21 Miller on Art, Altruism and Sexual Selection 21 of giving money are trying to make a successful display; just as are male hunters who go after big, inefficient prey rather than smaller, easier to catch prey. One possible explanation for the origin of altruism that Miller suggests is via a combination of sexual and group selection, as in the case of altruistic sharing amongst hunters that I described earlier. Hunters who share their food are making a sexual display; and as such the behavior can evolve by sexual selection. Because this form of sexual display is also group beneficial, groups with this behavior out-competed groups without it. In the hunting case, altruistic displays indicate hunting ability and the associated skills. However, many altruistic gestures are not so obviously cases where skills are being displayed. What can we say about these cases? Since the most obvious cost of altruistic gifts is their dollar cost, one possibility is that altruistic gestures are supposed to demonstrate the extent of the resources of the altruist. On this view, altruism is a form of conspicuous waste to show how much money or other resources a person has available; just as the peacock's tail is a conspicuous waste of the bird's developmental energy, thus displaying how much energy there is available. Those who are poor or sickly cannot make such large displays, and therefore they are sexually selected against by members of the opposite sex. If this dollar value view of altruism as a sexual indicator is what Miller has in mind, then there is at least one serious problem with his view how do we account for individuals tendency to praise altruistic acts - including extreme altruistic acts - that are not directed at them? On other theories of the origins of altruism, praise is a reward for altruism, since praise improves one s reputation and social standing it provides some individual benefit that allows altruism to evolve. However, on Miller s view there is no need for rewards for altruistic behavior to allow it to evolve, since altruism should be individually useful, due to its tendency to increase its possessor s sexual success. Miller does suggest that moral approbation

22 Miller on Art, Altruism and Sexual Selection 22 on the part of potential sexual partners is (at least partly) a manifestation of sexual interest. However, it is unlikely, given the way that altruistic praise operates, that both this view of the nature of moral praise and the dollar value view of altruism can both be true. If altruism is to act as an indicator of overall wealth, and more importantly, an indicator that can't be faked by poorer individuals, then altruistic gestures need to be made as a direct proportion of one's wealth 5. So wealthy individuals should give proportionately more than poor individuals, and large gifts should be proportionately more attractive than small ones. If moral approbation on the part of potential sexual partners is a reflection of the degree sexual interest, then big gifts should receive proportionately more praise than small gifts, ceteris paribus. However, it is not clear that the bigger in dollar terms the act of altruism, the more people praise it something else seems to affect the degree of approbation proffered. For example, people do not seem to be more impressed by a millionaire that gives $110 to charity than a poor person that gives $100. Nevertheless if art is a straightforward indicator of wealth, the applause for and thus sexual interest in altruism must be directed at the behavior that shows the highest cost. Another problem with the idea that altruism acts as a form of "dollar value" fitness indication is that there are easier ways for a person to find out what a person's wealth and status are than via their altruistic 5 There are three ways that gift size can increase as wealth size. 1) Gift size can be proportional to wealth size; 2) gift size can increase as a percentage of wealth size as wealth size increases, or 3) gift size can decrease as a percentage of wealth as wealth increases. Suppose relation 3) is the standard way of indicating wealth. Then for each dollar a person P gives, it appears that P is disproportionately more wealthy (e.g. suppose you give one dollar for each of the five first $1000 you own, then one for each of the next five $10000 dollars, etc.) Therefore, since the wealthier P appears, the more sexual opportunities P gets, it would be worth P s while to give more dollars than properly indicates his wealth to fake since the fitness costs of paying more dollars will be outweighed by the fitness benefits of disproportionately more sexual opportunities.

23 Miller on Art, Altruism and Sexual Selection 23 giving, which may or may not be well correlated with their total net worth. If these more reliable means of fitness indication are available, why waste time paying attention to altruism? An alternative way in which the costliness of altruism might act as a fitness indicator is if by choosing altruists, women are choosing good fathers. This form of sexual choice might work because altruists are generous - willing to help others, and hence probably their own children (p.334). However, there is a problem with this idea, too. The best fathers are nepotists, not altruists, since nepotists and altruists are both nice to their children, but altruists are a little bit too willing to give away the family wealth to charity. Miller thinks that maybe altruists do better with stepchildren (an inevitable part of the Pleistocene family) than nepotists. Possibly, but why should women choose altruists for this reason, when they can just directly choose men who are good with their children? Indicators are used to tell us about something we cannot directly observe in the individual we are judging. So Miller has not established how altruism is supposed to work as a fitness indicator, even if it is clearly costly. His case that altruism is a sexual adaptation is consequently considerably weaker than his case for art after all, it seems clear how art could act in courtship and as a fitness indicator, even if Miller s evidence that it does is not very strong. In the next two sections I will consider the serious alternatives to Miller s claim that art and altruism are sexual adaptations. Altruism, which does not seem likely to possess Miller s five characteristics, can be better explained in terms of genetic or cultural group selection. In the final section I suggest an alternative process, cultural sexual selection, which can produce traits with most of Miller s five characteristics; this might account for art if art does indeed turn out to possess those characteristics.

24 Miller on Art, Altruism and Sexual Selection An alternative explanation for altruism Given that altruism does not look like a sexual adaptation, it seems to be appropriate to look for an alternative explanation. The best explanations for altruistic behavior in the literature usually invoke some form of group selection (for a discussion, see Sober and Wilson, 1998). Group selection is a process by which groups or organisms are selected for based on their group level properties. Group level properties are different from individual level properties for example, an individual level property would be being selfish or being altruistic ; on the other hand a group level property would be composed largely of altruists. During group selection, groups give rise to different numbers of new groups due to their group level properties. We can then explain the prevalence of altruism in a population by appealing to the affect on group reproduction of having many altruists in groups altruists contribute to the fitness of everyone in their group and hence altruist-dominant groups tend to do better than groups that are mostly composed of non-altruists, all else being equal. This means that while altruists may decrease as a proportion of any group in each generation (since there is individual level selection against altruists because of the fitness costs they pay to others), altruistic groups contribute more members to the population as a whole, and the number of altruists in the total population tends to increase. Group selection explanations for altruism do face problems, however. The first problem is that group selection only occurs when there are stable, significant differences in the group level properties of those groups. This requires that group selection (for altruism in particular) can only occur in cases in which there is assortative group formation that is, group selection for altruism can only occur where altruists tend to group together, as do non-altruists. A second problem is migration of individuals between groups which happens in every population.

25 Miller on Art, Altruism and Sexual Selection 25 Migration, because it is random, tends to reduce differences between groups. A third problem is how to get group selection for altruism going, given that altruism tends to reduce the individual level fitness of individuals. In order to get groups with large numbers of altruists, there have to be reasonable numbers of altruists in the population to begin with. However, altruists are selected against by individual level selection when they arise. The fourth problem for group selection is how to deal with the relative pressure of individual level selection verses group selection unless groups periodically break up and re-form, altruists will eventually die out as members of any group. Ideally, there should be some way in which altruists can be helped to maintain greater fitness parity at the individual level with non-altruists. The following proposals have been made in the literature for dealing with these problems. For humans, Sober and Wilson (1998) argue that the first problem (assortative group formation) would not have been that much of a problem. In the earlier part of human history we belonged to small, flexible social groupings that allowed us to observe and talk about the behavior of others and thus make decisions about those with whom we wanted to associate (Sober and Wilson, p.141-2). The second problem (migration) can be avoided if altruism has a primarily cultural origin it is a trait that is socially learnt. This means that individuals coming into altruistic groups need not remain non-altruistic they can change their behavior appropriately; alternatively their children can come to acquire altruism, and hence, over generations, migration will not cause changes in the proportion of altruists in groups. The acquisition of altruism can be made more reliable via a conformist bias in learning (a conformist bias is a learning heuristic that leads the individual to acquire the cultural trait that is most prevalent in the group they are entering - Henrich and Boyd, 1998) or via the use of punishment (see the next paragraph for an explanation for how punishment works).

26 Miller on Art, Altruism and Sexual Selection 26 The solution proposed to the third and fourth problems is that altruistic behavior can become prevalent, and group selection become stronger than individual selection in altruistic groups, if there is some way of creating greater parity in the individual-level fitness of altruists and non-altruists (Sober and Wilson, 1998, p.142f). There are two ways to do this either increase the individual-level fitness of altruists, or decrease the individual-level fitness of nonaltruists (or both). This means imposing punishment on non-altruists, or offering rewards to altruists. Punishments do require some payment of cost on the part of the punisher, making punishment itself an altruistic behavior - Sober and Wilson call it secondary altruism. If the costs of punishing are low, the benefit of keeping other members of the group in line might outweigh the costs to the punisher; therefore punishing behavior might also evolve by group selection. (The same is true for rewards). The previous discussion suggests cultural group selection of altruism is a least possible. How might this explanation for altruism account for the extreme or showy altruistic acts Miller is trying to explain? We ve already seen that one of the important requirements for the occurrence of group selection for altruism is the presence of punishment or rewards for certain types of behavior. Groups can maintain altruistic behavior by punishing selfishness or by rewarding altruism. But this creates an interesting situation what is important to the individual is receiving the reward/avoiding the punishment, not offering the group benefit. In order to get her reward from the rest of a group, it is in an individual s fitness interests to be focused on making sure everyone (or at least those responsible for rewards and punishments) is aware of her contribution, even at the expense of the actual value of that contribution to the individuals she is helping. Hence individual selection favors showy altruism to maximize potential rewards and minimize punishment whilst still offering some group selective benefit in the form of some