| Index | ||
| Prologue | ||
| The Roper Report | ||
| Introduction | ||
| Section 1 | ||
| Section 2 | ||
| Section 3 | ||
| Section 4 | ||
| Section 5 | ||
| Section 6 | ||
| Section 7 | ||
| Section 8 | ||
| Section 9 | ||
| Section 10 | ||
| Appendix A | ||
| Appendix B | ||
| Perry's Tale | ||
| Pictorial Record | ||
Ovulation: cryptic. Females menstruate once to six times a year, at irregular intervals. This "irregularity" is characteristic of individuals, i.e. if the twin co-wives in a family group chance to ovulate simultaneously (a rare event), their next ovulation will not again coincide.
Mating: long term. Formerly thought to be for life, but it is now known that the mating bond is occasionally dissolved for reasons other than death, albeit rarely.
Gestation: five months; children invariably born in pairs, usually identical twins. Indeed, Henderson’s surmise that a single fetus will spontaneously resorb may now be regarded as confirmed. Under some circumstances, touched on below, the two kits carried in the same womb will have different fathers.
Sec.3.2 The relationship between co-mates has a significant influence on their copulation with their wives. Identical twins, the commonest sort of co-mate, will occasionally take turns mounting a wklwy mate (perhaps even trading places before both ejaculate), or copulate with her in immediate succession. But this is unusual. It is practically limited to the first dozen or so years of marriage, and is really typical only in the situation where a new co-wife has joined the family group–and even in such cases, such ‘sexual athleticism’ would count as the exception rather than the routine. The minimal pattern is for a male co-mate to copulate with each co-wife on alternate days, though during the first forty years or so of marriage it is commonplace for a male to copulate on three days out of five with each receptive female.
Sec.3.3 So far from there being any kind of rivalry between co-wives, as is so often cited in polygynous societies, among the wlko a single wife with young husbands is typically (proverbially, in fact) "on the lookout" for a co-wife, since a single wife will commonly be approached two to four times a day by her co-mates. All evidence suggests that copulation is pleasurable for wlkwim, but since wlko copulation is a lengthy matter, a wife with young children to take care of hardly has time for such incessant sexual attention.
It was long ago pointed out that since monozygous twins are genetically more or less identical, there is no "genetic advantage" to sexual competitiveness in the typical wlko family group. The relatively high frequency of copulatory acts, therefore, must be chiefly attributed to the pleasure it gives both participants. And this in turn is related to the cryptic and irregular ovulation of the wlko female (Sec.3.1). A further datum, only recently come to light (Sawyer Sec.6.02) is that the wlko spermatozoa are not very numerous in a single ejaculation (the discharge appears copious but as in most animals it mostly consists of the carrying vehicle, pheromones, and so on, and in the case of V. vulcus, (Fn 9) lubricants, Sec.4.2.1, 4.2.5, etc.); and in addition, they are simply not very viable. That is, the only possible strategy for reproductive success in V. vulcus for wlko co-mates to inseminate their wife or wives as often as possible.
The case is different, and noticeably so, with co-mates who are merely brothers (i.e., of different ages or are fraternal twins) or are not closely related, e.g. when one of the males is a replacement for a co-mate who died or has become incapacitated, and, though males from the same clan are preferred, may even come from a different clan altogether. Here, it is normal for the mating of one pair to arouse the other co-mate, if he is anywhere nearby, and he will attempt (usually successfully) to copulate with the female almost as soon as the first male is finished. See fn. 13. Evidence suggests, as does common sense, that non-identical-twin kits are almost entirely the result of such serial mating, and the kits in question will therefore almost invariably have different fathers. (Fn 10)
Fn 8. The reasons for this statistical difference are not certainly known but several possibilities seem obvious. Male mortality seems to be slightly higher than female mortality, for the usual genetic reasons, and perhaps because of the health risks consequent from copulation with monuxes (Appendix A). More importantly, a family group that loses one co-wife to death (or, rarely, departure) will in 47% of the cases studied simply carry on, perhaps only later being joined by a new co-wife. In the event of death or defection of a male, however, only 7% of the groups thus affected studied in the literature remained for more than five years without recruiting a new co-mate. The wlko who elected to continue indefinitely with a single adult male were as a rule older (135 years and over). Advanced age has three consequences: ‘starting over’ is harder to contemplate; finding a suitable co-mate of even roughly suitable age is difficult; and–the most important reason–such family groups are commonly busy taking care of (great-(great-(great-)))grand-children.
Fn 9. Sawyer took many vaginal swabs from wlkwim. Within two hours of insemination, live spermatozoa were hard to find. Even in the case of two single wives he examined–both young and both copulating frequently with their co-mates–by three hours after that last of as many as six vaginal ejaculations by two young males, he was unable to find a single living spermatozoon.
Fn 10. I have personally observed male co-mates mount both of their wives twice apiece in three quarters of an hour. The situation was unusual in several regards: the males in question had been married for only a month or two, and they were very young non-twins who had been brought together only after puberty, each having lost a twin brother with whom he had been sexually active (Sec.5.1). They clearly liked one another, and in fact were affectionate in a way that seemed to combine both friendship and "twinhood" in an unusual way; but the absence of the usual bonds between twin boys was most clearly evident in a degree of heterosexual competitiveness that was unique in my field experience.
The competitiveness was however good-natured, and the females not only tolerated the repeated sexual attentions but were as a rule fully responsive to all couplings. However, on one occasion I observed, the boys came back from the river and started to approach their co-wives for something like the fifth time that day. When the females saw their erections (just starting to emerge from their penis-sheathes) they laughed and teased the boys, saying things like "Come on, what do you think this is, a wlkatar?" and "Why didn’t they tell my parents you boys had rupellid blood?", and similar things. They allowed the boys to embrace them, and held them affectionately, and exchanged licks, but they were holding the boys in such a way as to make their genitals inaccessable to the young men’s erections. The young men didn’t say much, and seemed content to nestle in their wives’ fur without making any strenuous effort to penetrate them. In fact, as they were approaching their wives they were teasing one another under their breath, and their tails were wrapped around a thigh, a sign that they were embarrassed at themselves.
Interestingly, when co-mates are non-identical twins, even those with different (and even unrelated) fathers, as may result from a wlkatar, their behavior toward their spouse(s) is the same as the behavior of true identical twins.