INTRODUCTIONVanuatu is located in the Southwest Pacific some 850 km West of Fiji. (16 deg. lat.,168 deg. long. east of Greenwich) (See maps 1,2). Prior to independence in 1980 this archipelego of 74 populated islands as well as hundreds of tiny islets, was known as The New Hebrides. Combined, the islands have a total land mass comparable to the size of Massachusetts, but are spread across 650 Km. of Pacific Ocean.
In 1991 The Author happened upon a reference (1), concerning an area in the Sakau peninsula of the Republic of Vanuatu that contained "no less than seven strains of Hermaphroditic pigs". Being a "closet" reproductive physiologist and immediately recognizing the incorrect terminology of this statement (but no less intrigued by its content), I sought to contact the author for verification of this reference. He was unable to substantiate this quote, but was able to put me in contact with Kirk Huffman(14), an anthropologist, who had spent 17 years as curator of the National Museum of Vanuatu. Huffman substantiated the aforementioned quote with names and locations of islands that are said to have the world"s highest ratio of intersexual pigs (a more precise term for these particular animals) intersexuality is the state or quality exhibited by an individual of a normally dioecesious group in which both maleness and femaleness are to be distinguished in varying degrees and/or at different times)(3).
The original purpose of this study was simply to verify and document the existence of this rare sexual aberration. Early on It was realized that if this topic was to be investigated comprehensively, it had to become a part Biological-part Ethnological venture. During the two year preparation for this project, I was able to consult with reproductive and behavioral specialists and was made fully aware of the scientific ramifications of a study pertaining to this particular condition, prompting me to revise and develop this study far beyond original expectations.
In addition to verifying the actual existence of these pigs, I planned to plot their occurrence and distribution today as compared to the only other documentation dealing with this subject, written in the early 1900"s. In this article Baker(5) also states, "I hazard to estimate that there are between ten and twenty intersexes per hundred normal males in Sakau" (A penninsula on the northeast coast of the island of Espiritu Santo). The Author intended to enlist the Ni-Vanuatu (indigenous people of Vanuatu) whenever possible to assist with this project.
The purpose of this project was to conduct a culturally sensitive scientific study with the intentions of updating, amending, clarifying and continuing previous studies concerning pig intersexuality on the Islands of Vanuatu.
VANUATU NATIVE PIG HISTORY AND DESCRIPTIONVanuatu, a relatively young landform, appeared 22 million years ago when a series of massive deep ocean earth movements forced a chain of submarine volcanos to the surface(8). In addition to being a remote island group, Vanuatu has not had the time to evolve and develop the rich array of mammalian species as some of its closest mainland neighbors. Only six species of mammals are indigenous to these islands; all are bats, representatives of the suborders Megachiroptera (Flying foxes) and Micorchiroptera (insectivorous bats).
Most historians agree that the peoples of the Western Pacific originated in southeast Asia about 40,000 years ago, and through a series of migrations across Indonesia and the New Guinea chain, these people colonized many islands, including the Solomons and Vanuatu beginning about 3,000 B.C.(8). The earliest evidence of human occupation and settlement discovered in Vanuatu comes from a site on Malo Island in the northern part of the country. Archaeologists(9) claim that in about 1400 B.C., the most adventurous of these proto-melanesians (people of the Lapita culture) travelled by canoe,and brought with them yams, taro, and the predecessor of the native pig, Sus papuensis. This corresponds somewhat indirectly with some of the people of Malo's interpretation of the origins of the first life forms on that island. Through oral traditions, many locals still believe that the first humans to settle Vanuatu were also from Malo, but that they arose from a hole in Malo Pass. From this hole, along with the first man, also came the first Naravé (The national language of Bislama"s term for the intersex pig). Many people of Malo believe that their island was the first site of human and animal habitation. Contrary to popular European misconceptions, the first pig in the Islands did not arrive with Captain Cook in 1774, but with successive migrations of peoples from Northern Melanesia in much earlier times(1). Marshall(10) stated that "No anthropologist would admit for one minute that such a elaborate and complex pig culture could be established in less than several centuries and it would be a biological impossibility anyway for it took centuries, co-related with native culture, to produce this incredible ratio of bisexual animals."
Sus spp.(Incorrectly termed Sus papuensis,these pigs are S. scrofa vittatus X S. celebensis hybrids)(11)(30), the ingigenous pig which is still thriving today, seems to have to adapted extremely well to the climatic and geographic conditions of Vanuatu. These pigs can be found on almost every island in Vanuatu in both the domesticated and wild states. The most predominant characteristics of these pigs are those of hardiness, compact size and a long tapering snout. Much smaller than its European counterpart Sus scrofa, the adult boar will generally weigh no more than 100 kilograms. Hope (12) wrote in 1872 that "We found no difficulty in getting as many pigs as we liked for an adze apiece, but they were by no means in fine condition, and if it is true that these pigs are descendants of those left by Captain Cook in the last century, then they must have been wonderfully altered ... they are shaped like a West Indian peccary, black and hairy, long in the leg and hollow in every part they should be full, the only point in which they excel is biting". The colors of the native pig range from off-white to black. All colors and color patterns (i.e. spotted belted, and differential point coloration) (Hetzer(31)) are represented in these pigs, with the predominant color being an agouti/grizzled, ranging from light brown to black with lighter distal tips on the bristles. By proportion there seems to be a lower proportion of white and lighter colored animals apparently because they suffer severely from sunburn and do not thrive in these conditions and, thus have been naturally selected against(11). Sus spp. has a leaner body build as compared to the commercial high production varieties who have proven to be uneconomical in this humid tropical environment. According to Weightman(12), Paddon probably introduced the first European breed of pig when, in 1845, he brought many kinds of livestock, including pigs, from Australia to Aneityum, an island in Northern Vanuatu. There have been, as one might expect, many subsequent crossings of the European with the native pig. According to local oral tradition as related by Cheif Joseph of Molo, along with the smaller body size, comes a lighter body frame and skeletal system as exemplified in the skull thickness. I have been told on many occasions that "during the `Nimangki" (a ceremony celebrating a Ni-Vanuatu mans social climb), it should only take one powerful blow of the carved hardwood club to shatter the skull, thus killing the pig, whereas very often it takes several strikes to kill a European pig or one with European blood". Many of the wild pigs are found in the dense bush and are joined there by wild cattle, dogs, and cats who have escaped disadvantaged domestic situations. These wild pigs are extremely nervous and wary of human encroachment. Sows with very small piglets and rutting boars in the presence of females in estrus, have been responsible for aggressive attacks on humans and animals. One thing to be noted though, is the excellent physical condition of these wild pigs as compared to their domesticated cousins. In the wild state they are able to realize the potential of their breed and thrive. Domesticated pigs of both European and wild blood, who are generally penned or tethered, are frequently ravaged by unchecked infestations of kidney worms (Stephanarus coleri)(12). The sow is a good mother, giving birth to and successfully raising a limited number of piglets per litter (averaging 4 to 5 offspring) every 12 to 18 months in uncontrolled breeding situations(13). The young, being extremely precocious, can survive on their own after one week of age. All Piglets, however, do not have juvenile striped markings as stated by Weightman(12) but are born with the color and pattern they will possess at maturity. Of the 109 piglets observed in this study none was striped. One elderly pig pig owner recalled observing striped young in his youth. Young sows have been bred as early as 6 months of age but generally a female is beyond one year of age when she first farrows. Piglets may be born in any month of the year and the gestation period seems to fall within the range of many other species of pigs (112 to 120 days). The average litter size of today"s high production domestic swine is eleven piglets with the sows farrowing at least two times a year(14). The small size of Vanuatu"s pigs and their reduced litter size have been mistaken for inbreeding in the past, it is more appropriate to say that it is most likely an adaptation to maximize the nutritional, climatic, and geographical conditions available to residents of this tropical Archipelago. As in many areas of Melanesia,Pigs were originally, (but much less today because of the breakdown of "traditional ways") maintained in Vanuatu not as an item of daily consumption, but more importantly for the occasions of feasts, food exchanges, and trade. Pigs were used as payment for women in marriage and ritually sacrificed and feasted upon at "Nimangkis". In the northern part of Vanuatu, status within a village was earned by males through a series of grade-takings or "Nimangkis". The social system is dominated by accumulation and periodic sacrificing of pigs (preferably curved-tusked pigs). This tusked condition is produced by knocking out the top opposing canine teeth of a male or intersex pig at about 2 years of age. The opposing lower canine teeth grow unimpeded by wear, creating a complete circle by 7-8 years and after 12-14 years of intensive care and attention a double circle is obtained(4,12,14). Only such tusked pigs were of any importance to the men of early Vanuatu, whose main preoccupation was that of attaining chiefly status through "Nimangki". Even more important than a tusked boar was the tusked intersex pig or Naravé. Thus the intersex pig became the most important commodity in the social framework of men's lives in Vanuatu and remains so many remote areas today.
DISTRIBUTION OF INTERSEXESIntersex pigs are woven into the very fabric of Ni-Vanuatu culture. From the earliest accounts, (Coderington(15), Rivers(16), Baker(4), and Marshall(10) Intersexes appear to have been very numerous on many of the populated northern-most islands of Vanuatu. Two anthropologists, Coderington in 1891, and Rivers in 1914 made short references to intersex pigs while studying the diverse cultures of the New Hebrides . The first and only references to these intersex or integrade pigs were by Baker in 1925(17) and 1928(4) where he stated "on arrival in the northerly islands of this group, there were intersex pigs in every village of Espiritu Santo and Gaua". He continued, "little did anyone think that hidden away in a small group of islands in the Pacific were thousands of Intersexes" (although he only documented 91 in his findings).
Because of the difficulties in communication, and the remoteness of many villages, this report is by no means an absolute description of the distribution of population, domestic or wild, of these animals. It can probably be assumed that there are at least some intersex pigs in the approximate areas of their domesticated cousins as today's island pig management accounts for many cases of "escapees". I will begin with the original references and systematically account for their current distribution. The Intersexes referred to by Coderington(15) 1891 and Rivers(16) 1914 were merely references and mentioned only their cultural significance to the early "Tribesman" of the New Hebrides.
The "extreme abundance" of Naravé on the Sakau Peninsula (Baker(14))seems to have been drastically reduced to a point where the Author was unable to verify any accounts of Intersexual pig ownership in this area. There are still Naravé pigs kept on Gaua today, but not nearly in the numbers that were represented in "better times". Also in the northern Banks, Merelava accounts for two intersex pigs. There is an account of one intersex on the Island of Tongoa. Baker(4) also stated that on Efate and Malakula the intersexes did not occur. I was able to find accounts of the pigs on both of these islands. As recently as 1992 one was killed in South Malakula in an area where it had no ceremonial significance. Keeping Naravé pigs in northern Malakula, however, must have played a significant role in the early peoples' lives as was evident when a prominent Vao villager took me on a two hour walk into the bush, to a "Long forgotten" sacred "Taboo" place. Here he showed a lifesize, hand-crafted stone pig, with tusks. He related to me that this pig had been carved by his ancestors "many, many years before". Upon even closer examination I was excited to find out that this pig was indeed a hermaphrodite. This was to be my first introduction to tangible evidence of the existence of these unique aberrations.
I have recorded accounts of intersexual pigs still being kept for "custom" purposes (i.e. Nimangki ceremony) in the village of Patani on the nearly inaccessible northwest coast of Santo. These pigs are still evident on Ambae in the Northeast corner of the island, as is the case on Malo in its Northeast villages. These pigs are still plentiful by today's standards but not nearly as numerous as witnessed by Baker in 1925. On Malo alone in the area of Avunatari, 30 intersexes were examined. Villagers implied that there were additional animals in some of the adjacent bush villages. In the past 100 years there has been a great reduction in the number of intrsexual pigs on the Islands of Vanuatu. Two factors contributed directly to this reduction of these integrade pigs: massive human depopulation of the islands, through Blackbirding (a form of "labor recruitment" practiced here from 1803-1913), and disease brought by sandalwood traders and missionaries. Both factors were "coincidental" with a gradual diminishing practice of "custom ways" as is prevalent with many of the world's indigenous peoples. The progression of these and other environmental influences reduced the native population by almost 90% by 1935. White man's invasion and the strong arm of the missionaries insidious influence, which resulted in the loss of "old ways", began to undermine the very culture it came to save. By 1937 Marshall(10) stated "many other customs have been lost or seriously modified through the often brutal influence of white man's civilization .... while the people have lost a score of their important customs, they have grimly and tenaciously retained the culture of he pig". Today, only the elders maintain the practice of "Nimangki" and reverence of the Naravé pig. Along with this fading of tradition comes the influence of capitalism, the pig jaws with circular tusks that were once hung proudly on the "Big Man's" Nakamal(the name for the men's meeting place), now find themselves in downtown markets and jewelry stores for sale to tourists for hefty prices. It may then be a natural fact that when these proud men have gone "on top"(a place high in the mountains where one's spirit goes after death), the Naravé pig and its secrets will slip irrevocably into oblivion.
From personal interviews and past references(13), I was able to generalize that the Falé-Ravé (local term for a normal female pig known to have produced intersex offspring) will first farrow at approximately 1-1/2 years of age, and continue to be productive for 14 years, farrowing every 12-18 months (I'll use 15). Considering the average litter to be 4-6 (I'll use 5), birthing 12 times in her lifetime she will have produced approximately 60 piglets (50% male, 50% female). Of the expected 30 males born, each Falé-ravé is said to produce at least one Intersex in every farrow or approximately 20% of the offspring she produces(figures gathered from local lore). It is important to note that this only takes into account the small percentage of the population who are, in fact, "intersex producers" and not 20% of all males born to the entire population as Baker's figures represent. Nonetheless, this conservative estimation is still very impressive as the abundance of these intersexes is equaled nowhere in the world.
METHODS/PROCEDURESIn the last remaining strongholds where "custom" is still practiced, Naravé pig owners vehemently protect their most prized possessions. Many could not grasp the scientific aspect of my requests, while others, in a very direct manner, refused to allow me to "wound" their pigs in order to "take away" blood. It was at this point that Vira Joseph, the highly respected chief of Avunatari Village on Malo Island, came to my aid. Part contemporary/part "custom" man, Chief Joseph explained in words, as I never could, the importance of my study in regards to the preservation of their rapidly disintegrating "customs". He explained to the men of his village that by my studying and then recording the history of the Naravé pig, future generations might know the importance these animals played in the lives of their forefathers. With all that I, thankfully, was granted the opportunity to draw blood and obtain my "hands-on" documentation of ten pigs, seven of which were intersexual.
Examining internal anatomies was another problem altogether. Some owners would part with the young (without tusks) or inferior Naravé pigs with broken or missing tusks. The price range was from 8,000 to 80,000 vatu ($60 to $600 U.S.). With all but perhaps fetal pigs beyond the boundaries of this project's budget allotment, I purchased one young pig for dissection. Additional dissections arose from those animals ritually killed at upcoming Nimangki ceremonies rather than sacrifice any more from this unique gene pool for this study. I was not fortunate enough to be invited to the ceremony itself but was allowed to perform 6 gross anatomical examinations on the deceased pigs.
The general body form, coat colorations, and natural histories from each morphotype were determined through field examinations, recent and past literature, personal interviews with Ni-Vanuatu villagers and actual specimens examined. All ages designated for each pig described in this study are approximate and originated from the owners account for each individual pig. The field weights were estimated by the author.
Personal documentation from actual sightings was my primary form of verification whenever possible. Distributional data were acquired through personal interviews, surveys, and service messages. Personal visits enabled verification of sometimes conflicting accounts of the existence of these animals and also allowed me to conduct field morphological and behavioral studies. One particular procedure available to me was blood examinations (complete blood counts at the local clinic in Luganville and hormonal assays from serum sent to New Zealand with the aid of the Vanuatu Dept. of Agriculture). Three normal pigs (two normal males and one female) were also selected, in addition to the seven intersexes, to serve as controls. Each individual animal was hand-caught and manually restrained. The eyes were masked to disorient the pig, providing an opportunity to fasten a protective cushion around the valuable curved tusks before any attempt was made to throw the animal to the ground. The animal was restrained in lateral recumbency on its right or left side. With the legs and head restrained, a 21 ml. blood sample was drawn from the radial artery of the down-side foreleg. The external genitalia were examined and photographed. A skin biopsy (3 cm. diam. X 2 cm. thick, preserved in EDTA/TRIS) was removed from the up-side ear with a leather punch and a commercial premedicated, numbered, ear tag was inserted in the void left by the skin punch. (Owner's cooperation by their eagerness agreed to receive the "earring" as a gift). The pig was then released with the total procedure requiring 10 minutes per pig.
Complete Blood Counts(CBC's) and hormonal assay interpretations were run on seven intersexual pigs, (D, E, F, J, K, L, and M) table(1)(2), two normal males, C, N) and one pregnant female (B). Their CBC's were compared against the normal blood values for swine used at the Western College of Veterinary Medicine, University of Saskatchewan, Canada. These blood values have been compiled from the clinical laboratory, Department of Pathology; from O W Schalm(18) et al (1975) and Kaneko(19) (1980). Normal values of laboratory data are offered as a guide and it must be noted that values may vary depending on the individual laboratory as well as the sex, age, and geographical habitat of the target research animal.
The quality controls for testosterone were at 2 ng-assayed 2.4 ng (120%), 5.00 ng-assay 4.49 ng (90%), 10 ng-assayed 9.54 (95%). The quality controls for estradiol were at 20 pg-assayed 19.37 pg (97%), 50 pg-assayed 53.22 pg (106%) and 100 pg-assayed 146.37 pg (146%).
For testosterone 200 ul of sample was extracted with diethyl ether for assay.
For estradiol 3 ml of sample was assayed using the method described by Webb et al(35). The intra-assay coefficients of variation were 8% for testosterone and 9% for estradiol.
The antiserum for DHT was the same as that used for testerone. It was used at a dilution of 1:300. Major cross-reacting steroids were 5alpha dihydrotestosterone 75%, 5beta dihydrotestosterone 75%, 5alpha androstan-3alpha, 17beta-diol 37.5%, 5beta androstan-3alpha, 17beta-diol 16.5%, androstenedione 0.1%. The antiserum used for the estradiol assays was raised in an ovariectomized ewe against oestradiol-6 (O-carboxymethyl) oximine bovine serum albumin conjugate used at a dilution of 1:16000. The major cross-reactions of other steroids were estrone 7.3%, estriol 1.4%, estradiol 17alpha 1.4% and androstenedione 0.015%.
RESULTSCBC'S of the ten animals (Table 4) all fell within, or on the periphery of the range of norms for swine (Table 1). The research animals consisted of pigs ranging in age from approximately one to seven years. All animals came from the same area on Malo Island. Upon first observation (Table 2), the hormonal values of the representative samples cannot by themselves be interpreted. The ratios of estradiol to testosterone were generated and the following general conclusions may be drawn. Ratios greater than unity have been generally designated as female and those less than one generally designates maleness(27).Like the two normal males, all seven of the intersexes showed ratios less than 1.0. These observations seem to support the theory that Vanuatu's intersexual pigs are actually mal-developed boars. Pig "B", said by locals to be a pregnant female, showed a progesterone level of 10.6 ng/ml, consistant with that of a pregnant sow.
The results of the Dihydrotestosterone (DHT) test (Table 5) on the sera of pigs D,E,F,J,K,L,M were consistent with maleness. Of the 54 animals on which external examinations were conducted, there was a high degree of variability, the most common occurrences were in testicular (number, size, and location) and urogenital configuration. Findings for the intersexes varied from very "female" looking external genitalia with no testicles to a descended scrotal sac containing two large well-developed testicles (Fig. 4). Within this range were many different testicular presentations including an empty scrotal sac, one degenerate descended testicle, one large testicle, and one large and one small testicle represented. Of the animals examined, 61% or 33 animals exhibit no testicles whatsoever, 10 (or 19%) possessed 2 well-formed scrotal testicles, 8 (or 15%) had 1 normal descended testicle, and the remaining 5% had 1 small and 1 large or 1 small testicle present. As the intersexes' testicular development approached that of the "normal male" condition, there was a corresponding change in the position and length of the ventral labial commissure (V.L.C.) and the urogenital aperture (Fig. 3,4). When there were no testicles or scrotum present, the vulva seemed almost undifferentiable from that of the normal female organ except possibly for a slight reduction of the urogenital opening, and the presence of the corpus cavernosum (C.C.) may push the (V.L.C.) dorsally and laterally. The terminal end of the urethra is distinguished from the corresponding structure of the normal female by the presence of the bulbo-cavernosus. Correspondingly, as the testicles become larger and descend into the scrotum, the V.L.C. appears to become larger as the C.C. itself enlarges and begins to turn ventrally, taking the V.L.C. with it. The most developed phase that was examined was that of the "transitional" male pseudohermaphrodite in which two large testicles were situated in the scrotum and the projection, now much long