Library of Excerpts

Female Sexual Selection: Part 2

This page contains a collection of excerpts from sources used to support Shift Theory, an alternative theory of human evolution. Click here for an introduction to this new and unique theory of evolution.

See passage for Darwin's summary of male dominated nuclear family model of sexual selection by both sexes for different characters. (Darwin, C. (1871) The Descent of Man . John Murray: London p. 627)

"For my own part I conclude that of all the causes which have led to the differences in external appearance between the races of man, and to a certain extent between man and the lower animals, sexual selection has been the most efficient." (Darwin, C. (1871) The Descent of Man . John Murray: London p. 628)

"Sexual selection has been treated at great length in this work; for, as I have attemped to show, it has played an important part in the history of the organic world. I am aware that much remains doubtful, but I have endeavored to give a fair view of the whole case. In the lower divisions of the animal kingdom, sexual selection seems to have done nothing: such animals are aften affixed for life to the same spot, or have the sexes combined in the same individual, or what is still more important, their perceptive and intellectual faculties are not sufficiently advanced to allow of the feelings of love and jealousy, or of the exertion of choice. When, however, we come to the Arthropoda and Vertebrata, even to the lowest classes in these two great Sub-Kingdoms, sexual selection has effected much.
In the several great classes of the animal kingdoms,---in mammals, birds, reptiles, fishes, insects, and even crustaceans, ---the differences between the sexes follow nearly the same rules. The males are almost always the wooers; and they alone are armed with special weapons for fighting with their rivals. They are generally stronger and larger than the females, and are endowed with the requisite qualities of courage and pugnacity. They are provided, wither exclusively or in a much larger degree than the females, with organs for vocal of instrumental music, and with odoriferous glands. They are ornamented with infinitely diversified appendages, and with the most brilliant or conspicuous colors, often arranged in elegant patterns, whilst the females are unadorned. When the sexes differ in more important structures, it is the male which is provided with the special sense-organs for discovering the female, with locomotive organs for reaching her, and often with prehensile organs for holding her. These various structures for charming or securing the female are often developed in the male during only part of the year, namely the breeding season. They have in many cases been more or less transferred to the females; and in the latter case they often appear in her as mere rudiments. They are lost or never gained by the males after emasculation. Generally they are not developed in the male during early youth, but appear a short time before the age for reproduction. Hence in most cases the young of both sexes resemble each other; and the female somewhat resembles her young offspring throughout life. In almost every great class a few anomalous cases occur, where there has been an almost complete transposition of the characters proper to the two sexes; the females assuming characters which properly belong to the males. This surprising uniformity in the laws regulating the differences between the sexes in so many and such widely separated classes, is intelligible if we admit the action of one common cause, namely sexual selection.
Sexual selection depends on the success of certain individuals over others of the same sex, in relation to the general conditions of life. The sexual struggle is of two kinds; in the males, in order to drive away or kill their rivals, females remaining passive; whilst in the other, the struggle is likewise between the individuals of the same sex, inorder to excite or charm those of the opposite sex, generally the females, which no longer remain passive, but select the more agreeable partners. This latter kind of selection is closely analogous to that which man unintentionally, yet effectually, brings to bear on his domesticated productions, when he preserves during a long period the most pleasing or useful individuals, without any wish to modify the breed." (Darwin, C. (1871) The Descent of Man . John Murray: London p. 636-8)

<112 Richard D. Alexander (471)> "Fisher (1930: 58) used the term 'runaway' sexual selection for situations in which females (usually) begin to favour extremeness of traits in males, that are deleterious in every other respect (Trivers 1972). Within-species social competition is likely to take on 'runaway' sexual aspects for three reasons: (1) the interdependence of the adversarial parties causes the significance of change in one to depend on the traits of the other; (2) the traits involved in the competition are likely to be arbitary (and deleterious) in all other contexts; and (3) within-species groups of an ecologically dominant species such as humans are relatively immune to effects from other selective agents. When one's adversary continually remains similar or identical to one's self in all but the particular trait that is at the moment changing, when changes in one party depend solely upon changes in the other, and when other hostile forces are insignificant, then there are few or no brakes on change in the traits used in the competition, and little extrinsic guidance (cf. West Eberhard 1979, 1983). I believe that the current human arms race is the prime example of such a process, and as well a logical outcome of the history that such a process suggests for the human species (Alexander 1987).

"For males, the situation is totally different. They remain in their natal group, and since they cannot get pregnant, they do not risk anything by having six with relatives. It is the females in their group who stand to lose from such contact. We therefore assume inhibitions against sex with mothers and sisters. The way these inhibitions may come about is through early familiarity---the basic mechanism assumed to underlie incest-avoidance in a wide range of species, including our own. The principle is simple: individuals of the opposite sex with whom one has grown up since infancy fail to arouse sexual feelings. If this process is disrupted---as when zoos raise young apes in a nursery---sex between relatives is not that unusual. Without a common backround, there is no way of knowing, so to speak, to whom one might be related. Normally, however, early familiarity characterizes the relations of males with close female relatives, and keeps them from breeding." (De Wall & Lanting 1997: 117, Bonobo)

"There has as yet been no explanation for such a marked difference in the evolution of the forebrain in birds and mammals. It is possible that the piling up of ganglia upon ganglia in the DVR of birds reflects their winged way of life, facilitating a tree-dimensional orientation to their environment" (MacLean 1990: 45, The Triune Brain in Evolution) [note: this could be evidence of sexual selection]

"Two characters could hardly be wider apart than the size and development of man's brain and the distribution of hair upon the surface of his body, yet they both lead us to the same conclusion---that some other power than natural selection has been engaged in his production." (Wallace 1895: 197, Natural Selection)

"And in an extraordinary discovery made by Wayne Potts of the University of Florida at Gainesville, house mice appear to choose as mates only those house mice that have different histocompatibility genes from their own. They do this by smell. This preference maximizes the variety of genes in mice and makes the young mice more disease-resistant." (Ridley 1993: 76, The Red Queen)

"Two recent experiments support the idea that females simply have idiosyncratic tastes that have not evolved. Male grackles---blackish birds of medium size---sing only one kind of song. Female grackles prefer to mate with males that sing more than one kind of song. William Searcy of the University of Pittsburgh discovered why. He made use of the fact that a female grackle will go up to singing loudspeakers and adopt a soliciting posture as if waiting to be mated. Her tendency to do so declines, however, as she gets bored with the song. Only if the loudspeaker starts singing a new song will her soliciting start afresh. Such "habituation" is just a property of the way brains work; our senses, and those of grackles, notice novelty and change, not steady states. The female preferences did not evolve; it just is that way." (Ridley 1993: 164-5, The Red Queen)

"Thus, it is possible to argue with Ryan and Kirkpatrick that male courtship extragances reflect the innate tastes of females without abandoning the idea that those tastes are of use to the females in that they select the best genes for the next generation. A peacock's tail is, simultaneously, a testament to naturally selected female preferences for eyelike objects, a runaway product of despotic fashion among peahens, and a hadicap that reveals its possessor's condition. Such tolerant pluralism is not to everybody's taste, but Pomiankowski insists it does not stem from misguided disire to please everybody. On a paper napkin in a Indian restaurant one day he sketched out for me a plausible account of all the sexual selection theories working in concert." (Ridley 1993: 167, The Red Queen)

"I suggest that the neocortex is not primarily or exclusively a device for toolmaking, bipedal walking, fire using, warfare, hunting, gathering, or avoiding savanna predators. None of these postulated functions alone can explain its explosive development in our lineage and not in other closely related species....The neocortex is largely a courtship device to attract and retain sexual mates: Its specific evolutionary function is to stimulate and entertain other people, and to assess the stimulation attempts of others." (Ridley 1993: 338, The Red Queen)

"Miller's threory draws attention to several facts that have remained unexplained in other theories, namely tht dance, music, humor, and sexual foreplay are all features unique to human beings. Following the Tooby-Cosmides logic, we cannot argue that these are mere cultural habits foisted on us by "society." Plainly a desire to hear rhythmic tunes of to be made to laugh by wit develops innately. Following Miller we note that they are characterized by obsessions with novelty and virtuosity and much practiced by the young. From Beatlemania to Madonna (and back again to Orpheus), the sexual fascination to youth with musical creativity has been obvious. It is a human universal." (Ridley 1993: 340, The Red Queen)

"Christopher Badcock, a sociologist at the London School of Economics who unusually combines an interest in evolution and an interest in Freud, has propose a similar idea. He suggested that neotonic (or, as he call it, "paedomorphic") traits were favored by female choice rather than male choice. Younger males, he suggests, made more cooperative hunters, and therefore females who wanted meat picked younger-looking men. The principle is the same: Neotenic development is a consequence of a preference for it in one sex." (Ridley 1993: 343, The Red Queen)

"Something in the sensory system of ancestral fishes evidently predisposed females of the X. helleri line to prefer males with swords. Since no previous member of this large and successful group of fishes possessed swords (so far as we know), this sensory and cognitive bias exists for other reasons, and must be regarded as fortuitous with respect to the evolution of swords. Male Xiphophorus helleri must, in this sense, thank Lady Luck for their graceful extensions." (Gould 1993: 376, Eight Little Piggies)

"Bateson built an engenious device that exposed individual quail to five birds of the opposite sex, but of different degrees of relationship: a sibling nestmate, a sibling never seen before, a first cousin, a third cousin, and an unrelated bird. Both males and females generally preferred first cousins over all alternatives. ... Bateson therefore concludes, from this and other arguments, that quail may be following a highly abstract aethetic rule---prefer intermediary degrees of familiarity, not so close as to be cloying, not so distant as to be overly strange. If he is right, an elegant solution to the problem of avioding incest suggests itself. Quail are not Mendelian calculators. They are, rather, following a deeper, more abstract, rule of aesthetic preference that may be common to a wide range of animals and neurologies. Maximal attraction to intermediate familiarity will automatically exclude disadvantageous closest kin as potential mates. (Gould 1993: 379-80, Eight Little Piggies)

"This need for similarity is rooted deep in our psyche and is borne out by studies that show people who are happily married long-term are more likely to have identical spacing between their eyes and identical lengths of their middle fingers. As peculiar as this may seem, it's a very real statistic, showing that people become most intimate with others who have some (but not too much) genetic similarity." (Hartmann 1996: 114, Beyond ADD)

"The implications of these findings is that an individual is able to strike an optimal balance between inbreeding and outbreeding by learning about is immediate kin and mating with a member of the opposite sex that is slightly different from its immediate kin. What such a balance might amount to in practice has previously been uncertain. I report here that Japanese quail of both sexes, having been reared with their siblings, subsequently prefer a first cousin of the opposite sex. ( Bateson, P. (1982) Preferences for cousins in Japanese quail Nature 295: 236) [note: choice between sibling, sibling novel, 1st cousin novel, 3rd cousin novel, and non related novel stranger.]

"I might add that all women get married, are married young, and married during their entire reproductive period, but not all men are successful in finding wives, and many only do so later in their reproductive life spans. (Chagnon, N.A. (1979) Mate Competition, Favoring Close Kin, and Village Fissioning Among the Yanomamo Indians. In Evolutionary Biology and Human Social Behavior. N. Chagnon & W. Irons, eds. Pp. 97)

"Paternity probability appears to be very high among the Yanomamo, based on paternity exclusion tests conducted by my medical colleagues at the Department of Human Genetics, University of Michigan Medical School. Using several different antigen systems we tested blood saples from parent/offspring triads and, allowing for possible errors due to mislabeling specimens, estimated that the nonpaternity level is about ten percent." (Chagnon, N.A. (1979) Mate Competition, Favoring Close Kin, and Village Fissioning Among the Yanomamo Indians. In Evolutionary Biology and Human Social Behavior. N. Chagnon & W. Irons, eds. Pp. 98)

"In addition, displays of masculinity, such as fighting prowess and "waiter" (ferocity) are admired by Yanomamo women, and particularly aggressive men have an advantage both in soliciting the sxual favor of larger numbers of women as well as depressing the temptation of other men to seduce their wives." (Chagnon, N.A. (1979) Mate Competition, Favoring Close Kin, and Village Fissioning Among the Yanomamo Indians. In Evolutionary Biology and Human Social Behavior. N. Chagnon & W. Irons, eds. Pp. 101)

"Thus, with a low paternity probability, there is an inherent matrilineal bias to kin relationships and concomitant investment patterns. This may be significant for the formation of matrilineages as opposed to patrilineages." (Kurland, J.A. (1979) Paternity, Mother's Brother, and Human Sociality. In Evolutionary Biology and Human Social Behavior. N. Chagnon & W. Irons, eds. Pp. 155)

"Differential variation in adult reproductive success is determined in the mechanics of the mating system. First, the practice of polygyny by the Yanomamo results in some men having a disproportionate access to mates. Second, older and politically prominent widowers are likely to take young women as new wives, excluding younger men from early opportunities to reproduce. The net result is the while the sexes are nearly equally represented as adults (see below), male-male competition for wives ensures that only a fraction of adult males will dominate the reproductive contribution made from one generation to the next by females." (Chagnon, N.A., et. al. (1979) Sex-Ratio Variation among the Yanomamo Indians In Evolutionary Biology and Human Social Behavior. N. Chagnon & W. Irons, eds. Pp. 306)

"In regard to sexual dimorphism humans tend to fall in the region of mildly polygynous species, with males taller than females by about 5 -12 percent---slightly less dimorphic, for example, than chimpanzees (Clutton-Brock and Harvey, 1977a, 1977b). (Alexander R.D., et. al. (1979) Sexual Dimorphisms and Breeding Systems in Pinnipeds, Ungulates, Primates, and Humans. In Evolutionary Biology and Human Social Behavior. N. Chagnon & W. Irons, eds. Pp. 415)

"Two approaches are possible. First, extensive comparisons have already been made of sexual dimorphism between human populations of different geographic origins. these populations could also be compared with respect to breeding-system differences. Eveleth (1975) amd Eveleth and Tanner (1976), for example, compare a large number of populations of Europeans, Africans, Amerindians, Asians, and inhabitants of New Guinea in regard to sexual dimorphism in stature. Their conclusions are that Amerindians are the most dimorphic, followed by Asians and Europeans, with inhabitants of Africa and New Guinea more or less alike and the least dimorphic. Using recent history as the criterion, it would appear that African and New Guinea populations are the most polygynous of these five groups rather than the least as the demorphism data would suggest from comparisons with other mammal groups." (Alexander R.D., et. al. (1979) Sexual Dimorphisms and Breeding Systems in Pinnipeds, Ungulates, Primates, and Humans. In Evolutionary Biology and Human Social Behavior. N. Chagnon & W. Irons, eds. Pp. 417)

"Surprisingly, however, the findings also seem opposite to what might have been expected. Populations of African origin, whether located today in Africa or the New World, tend to have significantly lower sex ratios at birth, withthe highest sex ratios at birth and the greatest degree of adult sexual dimorphism recorded in Amerindian, Asian, and European populations." (Alexander R.D., et. al. (1979) Sexual Dimorphisms and Breeding Systems in Pinnipeds, Ungulates, Primates, and Humans. In Evolutionary Biology and Human Social Behavior. N. Chagnon & W. Irons, eds. Pp. 421)

"If, however, societies which impose monogamy upon their members by rules or law are separated from those in which, as with nonhuman monogamous species, monogamy appears to be voluntary (and the most efficient reproductive arrangement for individual males and females), then societies with such "ecologically imposed' monogamy appear to be less sexually dimorphic than others. This is the result that studies of other mammals would predict." (Alexander R.D., et. al. (1979) Sexual Dimorphisms and Breeding Systems in Pinnipeds, Ungulates, Primates, and Humans. In Evolutionary Biology and Human Social Behavior. N. Chagnon & W. Irons, eds. Pp. 435)

"In genetic systems, the direction of selection is unlikely to reverse frequently; once a correlation exists between fitness and some signal like antler size, sexual selection will continue to favor increased antler size. In cultural systems, the correlation is not with any particular hairstyle or skirt lengthy, but with any conspicuous display which signals ability to read fashion trends. Because of this shift in correlation, novelty in either direction may become an effective signal." (Low, B.S. (1979) Sexual Selection and Human Ornamentation In Evolutionary Biology and Human Social Behavior. N. Chagnon & W. Irons, eds. Pp. 467)

"I report here that in the monogamous swallow, Hirundo rustica, males with experimentally elongated tail ornaments obtain mates more quickly than males with shorter tails, and enjoy increased reproductive output in one breeding season. Such males are also preferred by females seeking extra-pair-bond copulations. Thus male sexual ornaments may also be maintained by female mate choice in monogamous species." (Moller, A.P. (1988) Female choice selects for male sexual tail ornaments in the mongamous swallow. Nature 332: 640)

"I conclude that tail ornaments in the monogamous swallow have evolved as a result of female choice. Because females prefer males carrying a slightly enlarged sexual ornament, such males will pair up earlier, have an enhanced probability of siring two broods and thus produce more offspring within one breeding season. These results are consistent with the Darwin-Fisher-O'Donald idea that males with longer tail feathers will be able to pair up earlier with females having superior non-heritable quality. It is highly unlikely that more attractive males get mates with high heritable viability, although it is possible that males with long tail feathers do get mates with superior quality that equates with double clutching ability. The widespread occurance of male secondary sexual ornaments in monogamous birds may similarly have arisen and be maintained by intersexual selection." (Moller, A.P. (1988) Female choice selects for male sexual tail ornaments in the mongamous swallow Nature 332: 641)

"Here we report the results of a study of mate preferences of the crested auklet Aethia cristatella, a monogamous seabird in which both sexes are ornamented. In two experiments we recorded the sexual response of male and female auklets to realistic opposite-sex models with crest ornaments experimentally shortened and lengthened within the range of natural variation. Males responded to accentuated female models with more frequent sexual displays, as did females to accentuated male models, confirming the idea that ornaments expressed in both sexes could be favored by mutual mating preferences. [Darwin suggested that in people only was it clear there might be mutual sexual selection]

"So, when a woman proceptively approaches this man and not that, she has de facto made a selection. On the other hand, if the man approaches her, she also decides to accept or reject. If, for whatever her reasons, she finds him "uninteresting" and turns away, she has selected him out. Or, if she responds positively to him, she has given him a chance to proceed. Either way, she makes the choice." (Perper, Timothy (1989) Theories and observations on sexual selection and female choice in human beings. Medical Anthropology 11(4): pp. 416)

"It also appears that men and women do not synchronize as easily as do two women who are good and close friends, who may sit at a restaurant table or stand at a party and fall virtually immediately into postural and movement synchrony." (Perper, Timothy (1989) Theories and observations on sexual selection and female choice in human beings. Medical Anthropology 11(4): pp. 421)

"In essense, in the ethnographic milieu I am describing, the women chooses a man who responds to her specifically and intimately, as best as she can judge that from his behavior during the courtship sequence. Thus, her choice is made "on-line," so to speak, by assessing his behavior, particularly his capacity to respond personally to her. This conclusion has a powerful implication. If she feels that she wants a husband with characteristics X,Y, and Z---say, certain looks, a certain degree of wealth and status, and certain interests in hobbies and leisure time activities---and she therefore searches out a population of such men, her success still depends on his being able successfully to pass through the courtship sequence." (Perper, Timothy (1989) Theories and observations on sexual selection and female choice in human beings. Medical Anthropology 11(4): pp. 424)

"Certain remarkable consequences do, however, follow if some sexual preferences of this kind, determined, for example, by a plumage character, are developed in a species in which the preferences of one sex, in particular the female, have a great influence on the number of offspring left by individual males. In such cases the modification of the plumage character in the cock proceeds under two selective influences. (i) an innitial advantage not due to sexual preference, which advantage may be quite inconsiderable in magnitude, and (ii) an additional advantage conferred by female preference. The intensity of preference will itself by increased by selection so long as the sons of hens exercising the preference most decidedly have any advantage over the sons of other hens, whether this be due to the first or to the second cause. The importance of this situation lies in the fact that the further development of the plumage character will still proceed, by reason of the advantage gained in sexual selection, even after it has passed the point in development at which its advantage in Natural Selection has ceased. The selective agencies other than sexual preference may be opposed to further development, and yet the further development will preceed, so long as the disadvantage is more than counterbalanced by the advantage in sexual selection. Moreover, as long as there is a net advantage in favour of further plumage development, there will also be a net advantage in favour of giving to it a more decided preference. The two characteristics affected by such a process, namely plumage development in the male, and sexual preference for such developments in female, must thus advance together, and so long as the process is unchecked by severe counterselection, will advance with ever-increasing speed. In the total absence of such checks, it is easy to see that the speed of development will be proportional to the development already attained, which will therefore increase with time exponentially, or in geometric progression. There is thus in any bionomic situation, in which sexual selection is capable of conferring a great reproductive advantage, the potentiality of a runaway process, which, however small the beginnings from which it arose, must, unless checked, produce great effects, and in the later stagas with great rapidity." (Fisher, R. A. (1930) The Genetical Theory of Natural Selection. Oxford. Clarendon Press pp. 136-7)

"In species so situated that the reproductive success of one sex depends greatly upon winning the favour of the other, as appears evidently to be the case with many polygamous birds, sexual selection will itself act by increasing the intensity of the preference to which it is due, with the consequence that both the feature preferred and the intensity of preference will be augmented together with ever-increasing velocity, causing a great a rapid evolution of certain conspicuous characteristics, until the process can be arrested by the direct or indirect effects of Natural Selection." (Fisher, R. A. (1930) The Genetical Theory of Natural Selection. Oxford. Clarendon Press pp. 145)

"A review of published reports showed that the sex ratio (proportion of boys) was low among infants conceived after ovulation had been induced. The difference between the observed sex ratio and an expected one of 0.514 was highly significant. These findings suggest that maternal gonadotrophin concentration at the time of conception directly affect the sex of the zygote." (James, William H. (1980) Gonadotrophin and the human secondary sex ratio. British Medical Journal 281: pp.711)

"Nevertheless, these findings raise a number of difficulties. One of these is establishing the reality of female choice in recent polygynous cultures. As the study acknowledges, it is very doubtful whether women do have a great deal of freedom to decide whom they will marry in most of the polygynous societies sampled. (Badcock, C. (1991) Evolution and Individual Behavior: An Introduction to Human Sociobiology Oxford: Blackwell.pp. 173)

But such paedomorphic trend culd be explained if we could somehoe show that it was part and parcel of the overall process of female choice for hunting skills. In fact, this is easier than it seems, because there are good reasons for believing that it would have been young, rather than mature, male hominids who first began to hunt. Experiments in which a colony of monkeys living near a beach were fed first with potatoes and then with rice left on the sand showed that it was a young member of the group who first discovered how to wash the food (as it happens, a female) and that the readiness to adopt this practice varied directly with age, younger individuals being more ready to take it up than older one. In the second place, it seems likely that younger, unmated males, probably associating in loose "all-male groups." would have been much better placed to undertake what must have been cooperative hunts than were older males encumbered with females and young who could not be left unguarded while their "owner" ran off chasing game. If homihid females with a taste for meat were prepared to reward younger, meat-giving hunters with matings, the reproductive success of such younger males would rise relative to that of older ones. This in itself could favor paedomorphosis by way of selection for youth, but it would also have set the scene for the other inevitable consequence of a meat-eating economy, in which greatly increased male parental investment could enable the gradual evolution of more retarded, paedomorphic infants. If we now ask what possible adaptive advantage such a general trend of paedomorphosis could have for human beings, the answer is obvious. It is simple that one, universal feature of paedomorphosis among vertebrates generally is that more immature forms tend to have larger brains relative to the rest of the body than more mature ones. Selection of young hunters by females would thereby have enabled selection for larger brains to come about as an inevitable, bu t unintended consequence." (Badcock, C. (1991) Evolution and Individual Behavior: An Introduction to Human Sociobiology Oxford: Blackwell.pp. 186-7)

"In species with elaborate pre-copulation courtship displays, male genital morphology is often less elaborate than in species without such displays. There seems to be a 'conservation of extravagance', with more elaborate pre-copulation displays making up for less elaborate gentital structures." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished theses. pp. 100)

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"Male and female traits cannot evolve separately. Because genes and developmental mechanisms are highly correlated across sexes within a species, most traits are homologous across sexes. By the same logic, homologous characters in males and females typically show high genetic correlations between the sexes, because similar sets of genes are expressed in similar fashion in both sexes. (Lande, 1980). Applied to sexual selection, this means that sons will tend to inherit their mother's mate preferences, and daughters will tend to inherit their father's sexually-selected traits. To cite an example from Dawkins (1986), one is as likely to inherit the genes for a large penis from one's mother as from one's father." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished theses. pp. 113)

"Biological skepticism about the extent to which sexually-selected traits can be elaborated is misplaced. This skepticism seems to be a historical remnant of scientific disbelief in the legitimacy of female choice and perhaps of scientific disdain for courtship and sex in general. Courtship is simply one adaptive domain among many, and highly elaborated adaptations for any one domain will typically decrease relative fitness in other domains. We have no reason then to suppose that sexually-selected traits will be under any special burdan to be useful in other contexts." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 119)

"Ever since Darwin, biologists have tended, when confronted with an adaptation that needs explanation, to invoke female choice of useful traits if male-male competition fails, and to fall back on female choice of arbitrary?traits only as a last resort. As this section has shown, there is little reason to suppose that the strength or relevance of selection pressures will fall off according to this conventional gradient. Rather, sexual selection through mate choice is a process equal in importance to natural selection to the external environment. The costs of courtship displays are no different in kind from the costs of other complex adaptations. Although there will be trade-offs between different adaptations and different domains of survival and reproduction, courtship displays will by no means tend to be sacrificed in favor of other traits. So sexually-elaborated courtship traits may have substantial costs to the individual, but they are not under any special burden in this regard. Moreover, the costs of sexual selection to the species as a whole may be minimal, and there may be substantial benefits in terms of population adaptability, speciation rates, evolutionary innovation, and even macroevolutionary success. (see Miller & Todd, in press). We cannot draw moral divisions between 'legitamate' adaptations that evolved through inter-species or male-male competition and 'illegitimate' adaptations that evolved through female choice, and we should not suffer from anxiety over the deleterious effects of sexual selection on species." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 123)

"Darwin (1871) observed that, whatever morphological traits have been elaborated through sexual selection, male animals typically use special behaviors to display these traits to females in courtship. The conspicuous presentation, waving, vibrating, and directing of horns, wattles, and tails towards females was among Darwin's strongest evidence that these traits did in fact evolve through sexual selection. Rarely does one observe a sexually-selected morphological trait tht is not displayed with some special behavior during courtship. This implies that, once an exaggerated morphological trait exists, the evolution of special behaviors that display it to best advantage can evolve fairly quickly and easily. Thus, we have indirect evidence that behavioral courtship displays are particularly likely to evolve under sexual selection." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 126)

"I suggest that most evolutionary innovations become established in populations by sexual selection through mate choice, or, perhaps more commonly, arise as phenotypic side-effects of sexually-selected traits. These novelties could be called "courtship innovations..... This theory is consistent with most important facts of speciation and evolutionary innovation, and it explains several otherwise baffling phenomena. It is consistent with the view that species are natural kinds that define themselves through mate choice criteria (e.g. Paterson, 1985), and with the punctuated equilibrium view (Eldredge & Gould, 1972; see Eldredge, 1989) the most evolutionary change in economic traits is closely correlated with evolutionary change in reproductive traits---i.e. directional natural selection operates most strongly around speciation events, when sexual selection also operates most strongly" (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 133)

"The possibility of runaway sexual selection for mental traits in humans has never to my knowledge been discussed before. So sexual selection through mate choice is the one great evolutionary process that has never been used as a possible explanation for human mental evolution, or for the rapid increase in brain size in our linage. And the reasons for this neglect are historical and ideological (e.g. Vicorian sexism and mechanistic behaviorism) rather than scientific." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 143)

"If our ancestors were choosing one another based on bodily features, and if that selection resulted in the species-specific elaboration of many of these features, and it is plausible that they were choosing one another based on mental and behavioral features, and that this selection could have resulted in the species-specific encephalization pattern described in chapter one. Thus, human sexual morphology can give us important clues about the evolution of human mentality." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 145)

"Yet again, theorists of human evolution have shown a blind spot with respect to sexual selection: what we are specialized for, both morphologically and behaviorally, is to seduce each other." Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 149)

"As we will see, humans are unusual in that both males and females have highly sex-specific, sexually-elaborated traits. In most animal species, only one sex, usually the male, shows sex-specific elaborations. This unusual human morphological pattern suggests that hominids underwent a pattern of mutual sexual selection with both males and females exercising selective mate choice with respect to somewhat different criteria." Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 156)

"In many cultures, unwanted body hair is removed by shaving, plucking, or waxing. These facts all suggest that Darwin (1871) was correct in suggesting that hairlessness has been subject to at least a moderate degree of sexual selecition by both males and females." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 166)

"Hairlessness would have opened hominids up to much closer sexual scrutiny. Body shape, health status, nutritional condition, and age would have become easier to assess by visual inspection. This cold have facilitated the evolution of human breasts, buttocks, and penises, which are much easier to assess than they would have been on a very hairy hominid. A relatively hairless face (except for sexually mature, bearded men) would have facilitated the evolution of subtle facial expressiveness. Finally, hairlessness allows skin colour to evolve under sexual selection, resulting in the wide range of colours visible across contemporary human populations (Darwin, 1971). (Of course, if we had retained our body hair and achieved our current geographical range, we might expect to see similar variation in the color of body hair across human populations, as we do for head hair.) The hairlessness provides a perceptual foundation for the sexual selection of a host of distinctively human bodily traits." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 167)

"Morris (1985, p. 53) claims that "the male eye is very slightly bigger than the female, while the female eye shows a higher proportion of white than the male". This suggests that the male eye may have enlarged as an allometric correlate of larger body and head size, but the female eye white may have evolved through slightly more intense sexual selection through male mate choice. Across all human cultures, the eyes are used conspicuously in sexual flirtation, with the alternation between nervous eye contact and coy glancing-away being used to signal sexual interest (Eibl-Eibesfelt, 1989)." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 171)

"The massive space devoted to hands, lips, tongue, and genitals in the primary sensory and motor cortices of the human brain can be interpreted as reflecting their sexual-selective importance in courtship, foreplay, and copulation, as much as their ecological significance." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 182)

"Thus, the human penis shows high species-specificity as an elaborated genital structure. Penis size also varies moderately across populations, being largest among African populations, smaller among European populations, and smallest among East Asian populations, but with substantial overlap (Rushton, 1987, 1988b, 1989b). Penises are highly age-specific, attaining their full resting size only after puberty, and are highly courtship-specific, attaining their full erect size only under sexually arousing conditions. Thus, penises show all the hallmarks of a morphological trait elaborated somehow through sexual selection." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 185)

Miller quoting Margulis and Sagean (1991) "Large testes and big penises are advantages only under conditions of widespread sexual promiscuity....The male with the best-timed copulation, most far-reaching ejaculation, and biggest testicular 'engine' able to produce the greatest quantity of sperm tended to win the 'game' of impregnation. Souped-up genitals with a lot of spermatic firepower, like incredibly expensive streamlined racing cars, are worth it only if there is some sort of race or contest. Otherwise they seem excessive." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 186)

"I have analyzed the effects of mate choice on the evolution of 3 male traits (the penis, male pattern baldness, and beards), 4 female traits (the breast, buttocks, hymen, and clitoris), and 11 traits shared by both sexes (hairlessness, long head hair, armpit and groin hair, eyes, nose, ears, lips, teeth, facial form, hands, and the sensory and motor 'homunculi' in cortex). The evolution through mate choice of sex-specific traits in both sexes, suggests that both male choice and female choice was important to our ancestors." "Since these chimpanzee species diverged only around 1.5 million years ago, the speed with which differences in sexual behavior can evolve under mate choice is clearly demonstrated." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 228)

"Many people assume that the opportunities for selective mate choice, particularly female choice, would have been severely limited under ancestral conditions, due to the supposed prevalence of arranged marriages, the exchange of women as chattel between families and tribes, the influence of cultural rules concerning incest, outbreeding, marriage, monogamy and adultery, the prevalence of within-class marriages in complex hierarchical societies, and the generally low status of women under 'partriarchy'. But there is strong archaelogical and anthropological evidence that many of these factors arose within the last 10,000 years (Fisher, 1992), and would not have restricted individual mate choice opportunities before that time. The economic and geographic demands of agriculture distorted human mate choice patterns, because agriculture requires long-term investment in preparing and maintaining a plot of land, and thereby reduces the physical and social mobility that underlay the free choice of sexual mates in hunter-gatherer tribes. Even a century ago, Westermark (1894) recognized that in pre-agricultural tribal societies, females excercised considerable powers of mate choice. With the rise of post-agricultural and post-industrial society, we are seeing a return to more 'natural' ancestral patterns, including more sexual experimentation in adolescence, higher rates of adolescent pregnancy, divorce, and 'infidelity', more serial monogamy, more single mothers, higher rates of bisexuality, and do forth. These new patterns probably represent the Pleistocene norm, not 'social problems' due to modern atheistic decadence. And under these new conditions, we see a dizzying variety of relationships emerging and of mate choice criteria being exerted. Thus, the sexual freedom and social complexity enjoyed by young people in contempory urban North America and Europe is probably much more representative of ancestral tribal conditions than the cloistered, oppressive patriatchy of medieval Europe or the lifelong monogamy of the mid-20th century industrial United States." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 237-8)

"Energetic joking, story telling, dancing, athletic displays, and love-making could all have been selected for partially as viability indicators." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 241)

"Our lineage can be visualized as an enormous parallel computer program for generating and processing behavioral courtship innovations: a genetic algorithm that cycles through an effective population size somewhere between 10,000 and 1,000,000, over 100,000 generations. At the beginning of the metaphorical computer run 1.8 mya, our ancestors had small brains, slow tongues, dull minds, and plain bodies; at the end of the run, 200,000 years ago, they had huge brains, quick tongues, creative minds, and ornamentally shaped bodies. But the computer analogy breaks down at the data/program dichotomy, because our ancestors were as once the program selecting among alternatives, and the data being selected among. The preferences and the traits co-evolved and self-organized." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 251)

"They were all the children of successful survivors but, more importantly, of successful lovers. And their own reproductive success would have depended on their inherited abilities to do the same. (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 252)

"Driver and Humphries (1988, pp. 43-4) also report tht human hunters share this strategy: "Australian aborigines capture kangaroos in the open by performing a display which seems to be similar in many ways to these crazy-dances. One individual does a crazy-dance in full view of the kangaroo, the prey apparently being so bemused by the unusual movements that it can be captured by other, non-displaying individuals." To the extent that hunting became important in human evolution, we may have evolved special abilities for generating crazy-dances to confuse and entrance prey animals. Such abilities may have evolved from, or facilitated the evolution of, protean dance behaviors in courtship." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 332)

"Novelty can mean three general things in relation to mate choice: attraction to new physical traits, attraction to new individuals, or attraction to new behaviors. Of these, Darwin focused on the first, briefly discussed the second, and mostly overlooked the third. Although Darwin emphasized the emergence of new traits across individuals, neophilia could also favor individuals who can regularly generate interesting new behaviors. This is why neophilia may be relevant to human encephalization, which represents largely the evolution of new mental capacities for protean (ever-changing, ever-new) courtship displays." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 370)

"Again and again, Darwin emphasized the diversity, elaborateness, novelty, and beauty of the adaptations that emerge by sexual selection through mate choice. No other evolutionary process seems to have intriqued the excited him so much. Whereas natural selection and male competition tend to produce convergent evolution onto rather mundane, pragmatic adaptations, sexual selection through female choice tends to produce divergent evolution that explores all the extreme corners of the vast space of beautiful morphologies and charming behaviors. Darwin considered these adaptations for beauty as biologically legitamate as adaptations for defense, predation, or battle. Although Darwin did not consider the evolutionary origins or functions of mate choice mechanisms in much detail, he did reveal a quite sophisticated understanding of animal minds, and of how mate choice actually operates to generate sexually-elaborated traits. By drawing the analogy between sexual selection by animals and artificial selection by humans, he showed how choice that is 'unconscious' but perceptive can drive evolution. By organizing Selection in relation to sex from lower animals through higher animals to humans, he showed how the importance of subtlety of sexual selection generally increases as mental evolution progresses. By recognizing the pitfalls of anthropomorphism in analyzing the aethetic preferences of animals, he gave sexual selection enormous flexibility in explaining even traits that humans might find repulsive. And by emphasizing the role that neophilia plays in generating particular sexually=selected innovations, he implied a more general role for neophilic selection in generating capriciously elaborated traits across many species. In many ways, Darwin's own conception of mate choice was deeper and more sophisticated than that of any theorist who followed in the next hundred years." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 373)

"There are some examples of neophilic preferences driving increased behavioral novelty in animal courtship displays. Bird song evolved through female choice and shows complexity and diversity. There is substantial evidence that female birds of some species prefer males birds that demonstrate larger song repertoires (e.g. Eens et al., 1991; Hiebert et al., 1989; Horn et al., 1993). Bird songs involve themes and variations (Podos et al., 1992; Schusterman et al., 1986), with novelties introduced from time to time. The novelties attract female attention and spread through populations of males in complex patterns of appropriation, diffusion, and modification, much like human jokes, melodies, or languages. Songbirds also have brains about twice as large as brains from comparable non-singing species (see Bateson, 1988), probably both so males can generate birdsong and so famales can process it. Novelty in behavioral courtship displays is not restricted to birds. The songs of large-brained humback whales are enormously long, complex, and change during and across breeding seasons, and are also used in courtship (see e.g. Payne, 1983). Courtship among dolphins also includes complex behaviors and sounds (see Pryor & Norris, 1991). And as Darwin (1971) noted, most animals with elaborated secondary sexual traits display them using special movements and dances during courtship. The complexity of many courtship dances seems to have been an object of sexual selection in its own right for many species (e.g. see Bastock, 1967; Burton, 1953, 1976; Eberhard, 1985; Robinson & Robinson, 1980). Thus, an intrinsic perceptual bias in favor of complexity and novelty may have driven the evolution of behavioral courtship displays in some birds and mammals. Of course, this sort of sexual selection for complex behavioral courtship displays is of particular interest in understanding human encephalization. As we will see in the next chapter, the most distinctive human behavioral capacities, including those for language, music, art, dance, and sexual play, can be viewed as mechanisms for generating protean courtship displays that play upon psychological predispositions in favor of novelty, variety, and diversity." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 379-80)

"Postulated functions for this neophilia include avoiding inbreeding and maximizing the genetic diversity of offspring (Small, 1993), and inducing paternal uncertainty to protect infants against infanticide by males (Hrdy, 1981). But among primate species, intense neophilia and female promiscuity seems to correlate with intense sperm competition. Perhaps neophilia also maximizes sperm competition, particularly between known and unknown males. Under condiditions of "runaway sperm competition", neophilia and female promiscuity, combined with elaborated estral swellings, facilitate sperm competition within female reproductive tract around the time of ovulation, thereby increasing the likelihood of females having male offspring with large testicles, high sperm counts, and high sperm motility. This pattern of runaway sperm competition seems to have occured among the common chimpanzees and pygmy chimpanzees. Because there is an inherent trade-off between behavioral female choice for individual male traits, and 'physiological female choice' for the best sperm (which required mating indiscriminately with as many males as possible, to maximize the sample size of sperm donors), female chimpanzees are surprisingly non-choosy for primates of their social intelligence. However, given female neophilia in favor of new males, males capable of displaying novel and unexpected behaviors may gain an advantage through exploiting neophilia as a perceptual bias (Ryan, 1990). In our ancestors, neophilia at the level of preferring new individuals could have then shifted towards neophilia at the level of preferring new behaviors by known individuals. Runaway sperm competitionturned into runaway brain evolution among our ancestors. This shift may explain the great differences between chimpanzee and human mental capacities and mating patterns." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 381-2)

"Electronic entertainment media reveal human neophilia particularly clearly because they act as perceptual and cognitive 'super-stimuli'. The careful selection and professional training of entertainers, writers, and directors, combined with systems of electronic editing, amplificaition, and mass distribution, allow the contemporary human to experience protean courtship displays (e.g. art, music, dance, story-telling) that are much more intensified, polished, and numerous than anything that would have been possible a hundred years ago, much less a thousand, or a hundred thousand years ago." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 387)

"The morphological evidence of secondary sexual ornaments on females from chapter 3, and the lack of sexual dimorphism in human brain size or in cognitive abilties, suggests that male mate choice was indeed an important driving force behind human morphological and mental evolution." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 406)

"...hominid females probably cultivated long-term sexual 'friendships' with a number of men who have different skills and resources to offer, just as females do in other anthropoid ape species (Smuts, 1985). Just as a male benefits from short-term sexual relations with a number of females, a female benefits from long-term sexual, provisioning, and protective relations with a number of males. ... Evidence from studies of human sperm competition suggests that ancestral females often did mate more than one male per ovulation (Baker & Bellis, 1989, in press; Bellis & Baker, 1990; Smith, 1984)." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 407)

"Thus, the evolution of social intelligence facilitated human encephalization not by initiating a simple linear trent towards ever-greater social intelligence, but by setting up the preconditions for a sudden, capricious explosion of behavioral courtship displays. So whereas runaway sexual selection in birds tends to affect plumage, runaway selection in higher primates may tend to affect brains and behavior (see Miller, accepted, b)." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 409)

"In the history of dance, music, and poetry, the development of radically new forms often elicits the following objection from critics: it is hard to assess the quality of a contribution that violates too many conventional rules. The same probably applied to 'critics' (i.e. animals choosing among potential mates) in other species: a moderate degree of rule-following facilitates comparisons among potential mates by establishing a common ground, a cognitive arena, and a behavioral context in which their diverse displays can be appreciated." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 414)

"This model also aimed to overcome the Cartesian mind/body dichotomy by considering morphological and mental evolution together. The unique morphological traits (e.g. large penis, large breasts, large buttocks, long head hair, hairless bodies, everted lips) that distinguish us form othe anthropoid apes and other hominids are all (1) explicitly valued by humans as sexual traits, (2) exaggerated far beyond the requirements of natural selection, (3) displayed prominently in courtship and attended to prominently in foreplay and copulation, and (4) fully expressed only after puberty - and are therefore likely to have resulted form processes of runaway sexual selection through mate choice. Likewise, the unique psychological traits (e.g. language, music, art, sexual play, conceptual play, and ideology) that distinguish us from other anthropoid apes and other hominids are also (1) explicitly valued by humans as traits relevant to mating, (2) exaggerated far beyond the requirements of natural selection, (3) displayed and used prominently in courtship, and (4) fully expressed only after puberty - and are therefore also likely to have resulted from processes of runaway sexual selection through mate choice. No other theory of human evolution can claim this sort of concordance between morphological and mental evolution." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 436)

"Just as selective mate choice by females probably drove the adoption of hunting in our early ancestors (Hill, 1982; Tanner, 1981), it also probably drove the adoption of other male provisioning improvements. Thus, the rise of economic and political complexity, the division of material labor, and the speed of technological innovation, could have resulted from male attempts to garner greater material benefits in order to attract the maximum number and quality of female mates." (Miller, Geoffrey F. (1994) Evolution of the human brain through runaway sexual selection: the mind as a protean courtship device. unpublished thesis. pp. 464)