James "Mac" McIntyre had been scouting the Republic of Vanuatu for six weeks without success. Starting in the capital of Port Vila, on the island of Éfaté, the stocky, energetic field zoologist—former rancher, carpenter, and logger—had hopped island to island, traveling by prop plane and motorboat, talking to everyone he met: fruit vendors at open-air markets, fishermen at boat landings, loungers on street corners, expatriates in bars. Where could he find the animal the islanders referred to as "pig half-man half-woman"?
No one could tell him—or at least no one would. The native Melanesians, who call themselves ni-Vanuatu, were generous and hospitable, but when it came to pigs, some of them grew a little shy. Others didn't seem to know what he was talking about. Still others remembered the pigs as part of a tradition that was long gone, a way of life that had died with their grandfathers.
McIntyre had been attracted to the southwest Pacific two years earlier by a curious reference in an American travel guide. "I was sitting in the library, leafing through travel magazines, fantasizing as I often do," he says, "when I came upon something called the South Pacific Handbook." Under the section on Vanuatu, the 1989 book made a startling claim: the Sakau peninsula, on the island of Espiritu Santo, was supposedly home to "no less than seven strains of hermaphroditic pigs."
"Well, being a zoologist, I knew that couldn't be right," McIntyre recalls. "But I was intrigued." He called the book's author, David Stanley, who put him on to one Kirk Huffman, an English anthropologist who had spent 17 years as the director of Vanuatu's national cultural museum. Huffman had retired to Spain, but happily confirmed the existence of "intersex" pigs in remote areas of his former haunt, and encouraged McIntyre to pursue them. "He said no research had been done on this," McIntyre remembers. As an independent researcher, a 42-year-old special education teacher in northwest Florida who quit a career at a rare animal breeding center so he would have more time to chase down rare species on his own—McIntrye had heard enough to be hooked.
The strange intersex pigs of Vanuatu, in the far southwest Pacific, may help unravel the mystery of maleness.
Spurred further by correspondences with other scientists he knew, McIntyre became obsessed with the pigs of Vanuatu. He studied everything he could find on the subject, which wasn't much. At last, in 1993, he pressed his then-employer, the White Oak Conservation Center of Yulee, Florida, for a leave of absence, emptied his bank account ("my kids' college tuition"), and set out. For the White Oak Center, he had traveled all over the U.S., once even brought back okapis from the Ituri forest in Zaire. But this was different. He was headed halfway across the world, to a remote archipelago—alone, without contacts. What was he going to do? How was he going to proceed? He didn't know. His only plan was to find those pigs.
"I took a chance," McIntyre says. "People told me I was crazy, but I knew I couldn't live with myself if I didn't try."
Up to this point, he had "powered through" the inevitable second thoughts. But now, in Espiritu Santo, after six weeks of fruitless effort, the accumulation of doubts was starting to weigh him down. His money was dwindling. He wondered exactly what he was doing here, 500 miles west of Fiji.
He had flown down to the island of Malekula, to inquire of a man there someone had told him about, and had met with a now-familiar answer. "No, sorry," the man said. The pigs were "long time ago." At the same time, however, McIntyre remembers, "This guy was excited. There was something he really wanted to show me."
At the man's insistence, the two drove inland two hours, over rough roads through mountainous rainforest. Then they got out and walked another two hours through the bush. Once McIntyre asked how far they were going. "Long way, lilibit," his host replied in Bislama, the local pidgin dialect. McIntyre had already heard the phrase, and knew it could as easily designate an overnight trek as a five-minute jaunt.
Finally, however, they came to a small clearing—an old ceremonial place, overgrown but still populated by a group of fading stone effigies. There were statues of a man, a woman, a child. Lastly, partially obscured by the surrounding bushes, there was a giant stone bowl carved in the likeness of a pig: a pig with both teats and curved tusks; both a vulva and testicles.
Doug Greger happened on the intersex pigs of Vanuatu by a different path: He followed his nose. Greger, a Ph.D. student in reproductive physiology in Penn State's department of dairy and animal science, is a big, bearish man whose face routinely fractures into a wide grin; like McIntyre he is 42, has a family, and is given to storytelling. In 1992, he had started looking into the boar taint problem.
Specifically, Greger was investigating the metabolic "pathway," or series of steps, that leads to production of the steroid androstenone, an important component in a pig's pheromone system. Androstenone, Greger explains, is produced in the testes and released into the blood. One of its products, androstenol, is sequestered in the salivary glands. "When a boar is sexually excited, he froths at the mouth, which releases the pheromone, and if the sow is in heat, she goes into what is called the standing reflex—she is immobilized, and allows the male to mount her."
The steroid's musky odor is popular with humans, too: perfumes like Jovan's "Andron" and "Realm" incorporate related steroids. Although there is no conclusive evidence that androstenol has pheromonal qualities in Homo sapiens, Greger reports, in one study, college-age women who wore a necklace impregnated with the steroid noted an increased likelihood of striking up a conversation with a strange man. "I smell it in a lot of perfumes, both male and female," he says. "It's a very strong scent."
Too strong, actually. For in addition to showing up in the saliva, androstenol—or rather its precursor, androstenone—is stored in the male pig's fat. In this form, the steroid, instead of a pleasant musk, gives off what Greger calls a "foul, urine, sweaty odor. Turns out it's one of the major components in human underarm odor." This distinctive bouquet is particularly noticeable when the fat is heated, i.e., cooked. Thus the meat of the male pig possesses what is known as boar taint. To most palates, it is simply inedible.
The popular remedy for this condition is to render boars into barrows. "Virtually all male pigs destined for meat production are castrated, usually within the first four or five weeks of life," Greger says. "Boar taint is the reason." Absent the testes, there is no androstenone, and no androstenone means no funky smell.
From a food-production perspective, however, if from no other angle, castration is a less than elegant solution. "Boars produce less fat and more muscle than barrows," Greger says, "on less feed. It adds up to about a 10 percent improvement in production efficiency. In other words, it would be economically advantageous to raise boars, except for the taint." Which is why Greger decided to investigate how androstenol is made. He wanted to see if he could find another, less drastic, way to prevent the hormone's production.
The making of steroids, in pigs and humans alike, starts in the pituitary gland, where luteinizing hormone is released into the bloodstream. When this catalyst reaches its glandular destination, there begins a cascade of hormonal events, with each step governed by the presence of one or more enzymes. The final step, if all goes well, produces the active form of the steroid.
Greger wanted to tease apart this particular enzyme pathway. To do so, he says, "I wanted to find a pig that had a defect in that pathway." Ideally, he would know this pig by its (non)smell: the absence of any taint.
Unfortunately, actually finding an untainted boar, he quickly realized, might require screening thousands of animals. And locating that many male pigs that had escaped castration would be next to impossible.
In the course of his studies, however, Greger had observed something in the literature. The enzymes that produce androstenol are the same ones involved in the synthesis of testosterone. Defects in the testosterone pathway, he reasoned, should be easy to spot. They would result in intersex conditions: pigs that exhibit incomplete physical characteristics of both sexes.
Intersexuality is not too uncommon an occurrence: It happens in about one percent of all pigs, Greger estimates, as a result of a hormonal goof-up during development. In the vast majority of cases, he adds, the intersex condition is masculinization of a female pig—the result of an untimely prenatal exposure to androgen. "In these pigs you always find uterine tissue in addition to testicular tissue."
There is, however, a much rarer kind of sexual hybrid. In this case a genetic male, because of a defect in the enzyme pathway, gets insufficient exposure to testosterone. The resulting animal, when mature, has external genitalia that is predominantly female in appearance, but male internal organs—no trace of a uterus or vagina. The condition is known as male pseudohermaphroditism.
"There's been a lot of interest in male pseudohermaphroditism in humans," Greger says. The main reason for this interest, he says, is that defects in testosterone metabolism, and specifically problems with the last step of the pathway, the conversion of testosterone into its far more active metabolite dihydrotestosterone, or DHT, have been implicated in two very common afflictions of the adult human male: prostate enlargement and baldness.
The conversion of testosterone to DHT, Greger explains, is controlled by an enzyme called 5-alpha-reductase (5R). This enzyme was discovered, and its role determined, by the study of human male pseudohermaphrodites in small isolated villages on the islands of Santo Domingo and New Guinea, where the condition tends to occur more frequently due to inbreeding.
"Typically, these individuals are born and raised as females," Greger says, "until, when they hit puberty, they "become" males—they develop a male body type. But they are infertile, and have small prostates and little beard growth. This is because while testosterone governs muscle growth, DHT is needed for development of the prostate and for beard growth."
The discovery—by its absence—of 5 R's crucial role in the production of DHT, Greger says, has sent drug companies on a chase to develop a way to inhibit the enzyme, since once a man reaches maturity DHT can do more harm than good. Merck has recently come out with the first of these drugs, dubbed Proscar, which is currently marketed for the treatment of prostate enlargement.
Knowing that the testosterone pathway parallels the one for androstenone, Greger decided to try a similar inhibitor drug in pigs.
"It worked in vitro," he says. "We were able to inhibit the production of boar taint steroids. At that point I envisioned using a 5aR inhibitor in male pigs—to shut down hormone production just before slaughter.
"But when I went to the meatpacking industry looking for funding to go further, they were afraid of potential side effects. A 5aR inhibitor would have to be given in large doses, right up to slaughter—which means it might show up in the meat. It would take a lot of trials to prove it wasn't, anyway. They figured it would never get past the F.D.A.
"So I abandoned the idea. I decided that instead of working on an inhibitor I would go after the gene involved."
He was in the right place to do it, working at the time in the U.S. Department of Agriculture's Beltsville laboratory. "There's a swine genetics lab there," he says. What he needed, however, was pigs: specifically pigs with a deficiency of 5aR. "I figured all I had to do was find some male pseudohermaphrodite pigs, and they would show me the way."
Finding one such pig would probably not be too hard. Coming up with a large enough population for a scientific sample would be another matter. Greger scoured the literature, but every citation he found involving intersex pigs was a reference to masculinized females. All but one, that is. In a monograph published in the British Journal of Experimental Biology way back in 1928, Oxford University zoologist John R. Baker had reported a new type of mammalian intersexuality, "interpreted as genetic males in which the testicular hormone has been produced too late in development." Baker had encountered these animals in astoundingly large numbers while documenting the fauna of the remote South Pacific island group then known as the New Hebrides—what is now called the Republic of Vanuatu, where Mac McIntyre had gone searching in 1993.
In Vanuatu, intersex pigs once stood at the very apex of a culture.
Pigs were the principal objects of wealth: They were accumulated, traded, loaned, and paid out to resolve disputes. Pigs were also the central religious object: They were pampered, revered, and finally sacrificed, their skulls bashed in with a sanctified club in a ritual ceremony that moved a man up the social ladder. A set number of pigs of a certain value each were required for the attainment of chiefly rank. As the pigs were killed, the killer assumed their spirits, gaining power and prestige among his clan.
Only male pigs had value in this complicated system, and males were valued according to the length of their tusks. In order to let the tusks grow unimpeded, the opposing upper canines were knocked out. As a result tusks often grew until they formed a complete spiral, or two, or even, in legendary cases, three—each circle reportedly requiring seven years' growth.
But tusks were not the only measure of value. On some of the northern islands the intersex condition was considered supremely desirable. In these places, the so-called Narav´e; pig was the holiest creature of all. In normal populations (pig and human), this type of male pseudohermaphroditism occurs only once in 20,000 births, Greger notes. By selective inbreeding over the course of centuries, however, the villagers of the northern islands of Vanuatu raised the incidence of Narav´e; pigs to an estimated 10 to 20 percent of all males.
Baker duly reported this phenomenon. So, in less scientific fashion, did another old Oxford hand, the biologist, raconteur, and sometime Baker collaborator Tom Harrisson. The latter spent a year in the New Hebridean bush during the mid-1930s, living among a people who in some villages still practiced cannibalism. His subsequent book, Savage Civilization (full irony intended), is a quirky classic, an amalgam of travelogue, natural history, and sympathetic ethnography that documents the social and religious aspects of the pig culture in vivid detail.
Word of this culture even brought Hollywood to the South Pacific, first in the person of screen legend Douglas Fairbanks, who, according to Harrisson's account, appeared like a vision in flame-orange pajamas on the immense deck of a million-dollar yacht which glided into an island harbor just as he, Harrisson, happened to be trudging along the shoreline, after months in the highlands eating only yams. Fairbanks' crew snatched up the emaciated biologist, the story goes, and straight off began to administer a succession of perfectly chilled gin slings. A few days later the actor sailed off, leaving in Harrisson's charge a small crew, a Bell and Howell camera, and several reels of film, with instructions to record the most colorful native stuff for the newsreels.
Only a few years later, a young American naval officer named James Michener came to the New Hebrides as part of the huge allied force that was stationed there during World War II. Tales of the South Pacific, Michener's postwar Pulitzer-prize-winner, details the pig culture, but leaves out the intersex part. (Pigs and their tusks even showed up in the subsequent stage and screen versions.)
For Greger, finding Baker's paper and the subsequent books was tantalizing. Here, if anywhere, would be a population of intersex pigs big enough for a useful study. But how would he get samples? There had been no scientific reports since Baker's. Even Michener had left the islands half a century earlier. Since then, the New Hebrides had modernized, de-colonized, changed its name. Did the Narav´e; pigs even exist any more?
Greger went back to the library, this time to the anthropological literature. There he found references to William Rodman and Margaret Rodman, a husband and wife team of Canadian scholars who had worked in Vanuatu as recently as the late '80s. He fired off a letter, and Margaret Rodman mailed an encouraging response. Yes, the pigs still existed. She and her husband had themselves attended numerous Nimangkis, the pig-killing ceremonies by which men attained rank. And Vanuatu, she wrote, with its coconut crabs and black sand beaches, was a lovely place to conduct research.
Soon after hearing from Margaret Rodman, Greger, as excited as he was, decided to put the Vanuatu pigs on the back burner. "It looked like it was going to turn into a very long-term project," he says. "I knew I had the kernel of a good idea, but I also knew I needed to get my Ph.D. first, so I could get a good job."
He decided to come to Penn State to work with Dan Hagen, one of the few American researchers who was actively involved in the boar taint problem. Half forgetting about the South Pacific, Greger threw himself into looking at other ways of preventing androstenone production. Then one day in January 1995, the siren called. Greger was browsing in the travel section of a local bookstore. "I picked up Frommer's Guide to the South Pacific," he remembers, "and looked up Vanuatu." There he found mention of one Fred Kleckham, "who was described as being an Australian who had worked as an artificial inseminator in the beef industry—Vanuatu is trying to build up its beef export business—but had chucked that job and was now leading wilderness tours.
"I figured this guy would know something about these pigs, so I wrote him a letter. He wrote back. Yeah, he said, he knew of the pigs—and did I know that there had been an American over there working on them? Fellow by the name of Mac McIntyre, from Fernandina Beach, Florida."
After those six pigless weeks, McIntyre's summer of '93 had turned into hog heaven.
One day, shortly after he had seen the stone pig, he noticed a man following him down the street, keeping a discreet distance. "I wasn't scared," McIntyre recalls, "because violence isn't a factor over there. So I turned around and stuck out my hand. Turns out he had a Narav´e; pig he wanted to show me."
Soon, McIntyre was to be connected with a man named Vira Joseph, chief of the village of Avuntari on the island of Malo. McIntyre describes Chief Joseph as "part cultural man, part today's man"; on the acknowledgements page of the scientific manuscript he wrote on his return to Florida, he notes: "A finer man on Vanuatu I did not meet." As both a chief and a fieldworker for the National Cultural Museum, Joseph was anxious that the dying tradition of the pigs be documented and so preserved.
On the day they met, McIntyre says, he and Joseph walked for eight hours without rest, passing from village to village. "He showed me Narav´e; after Narav´e; after Narav´e;. I took pictures, and wrote physiological descriptions as best I could." Then, having verified for himself the pigs' existence, McIntyre decided he'd try to get some blood samples.
"I didn't want to push it," he says, "so I spent time going around to villages, becoming a fixture. At first, when I walked into a village, children would scream and run—they had never seen a white man before. I had to build trust. I spent time working in their gardens, playing with children, drinking kava with the men." (Kava is the non-narcotic drug of choice on Vanuatu, a euphoric brew made from a kind of pepper plant.) Finally, he got around to asking whether he could draw a bit of blood.
"Why should we let you harm our pigs?" he remembers the islanders asking him. "And I said, ';It doesn't harm them.'" At last, to prove it, he drew some blood from his own arm. "When I didn't get sick the next day," he says, "that was enough for them."
Once he had been granted permission, however, there remained the obstacle of actually taking the samples. This task turned out to be even more hands-on than McIntyre had anticipated.
"Because I'm not a veterinarian," he says, "I am not allowed to use knockdown drugs. And because no one else would grab a pig and throw it down—or even offer much assistance until the pig was well-restrained—I had to go grab 'em myself. Lots of times it was best of three falls—me against 200 pounds of angry pig."
Make that angry tusked pig. And if he broke a tusk in the tussle, the pig was his to keep, at a cost of $600 American. Undaunted, McIntyre deputized one young islander to draw the blood, taught another how to work his camcorder, and dove in. In one "26-hour" day, he managed to get samples from a dozen pigs—nine Narav´e;s and three normal boars—and then to transport the blood safely to a medical clinic where it could be spun down, separated, and frozen before it spoiled. Nor did he buy any pigs.
Back in Florida, one day in February 1995, McIntyre got a message on his home answering machine from a Doug Greger at Penn State, asking for a return call.
"At first," McIntyre recalls, "he seemed a little put off. When I called back, he said: 'So who are you? And what did you do?' He considered this whole thing his baby—and of course I considered it mine. Then we broke the ice."
By this time, McIntyre knew he lacked the scientific expertise to proceed much further with what he had dubbed the King Nara´e; project ("King," he writes, for his great aunt Lulu P. King, who had fired his early love for nature and for faraway places). He sent his preliminary data to Greger, who could interpret it from an endocrinologist's standpoint. In March, when Greger gave an informal talk on the subject at his department's bi-monthly colloquium (dubbed, inevitably, "Sex Night"), McIntyre flew north to sit in—and to convince Greger to return with him to Vanuatu that summer.
"The hormone assays confirmed what looked like a deficiency in testosterone," Greger says. By comparing levels of testosterone against those of DHT, he determined, however, that the problem wasn't with the enzyme 5aR: It had to be something farther back along the metabolic pathway. "But we couldn't be sure with such a small sample. So we set about planning a trip, to get more data. For me it was still a side project, but Mac was willing to foot the bill."
With a small grant from McIntyre's sponsor, the Perez Trading Company, the two men left for the South Pacific the second week in June. From Los Angeles they flew to Fiji and then, after a 24-hour layover, on to Port Vila. Then they went island to island, revisiting McItyre's contacts and retracing the steps of earlier explorers.
"We went to all the places Baker had mentioned back in the '20s," Greger says, "including Hog Harbor, where he claimed to have seen 125 intersex pigs in one day." On the main islands, however, there were very few Narav´e;s left.
On the more remote islands, their luck was better. When they arrived on Malo, Chief Vira Joseph treated them as honored guests. "One of the first things I asked the chief," Greger remembers, "was 'How do these pigs taste?' Well, neither he nor his wife spoke English, but they both indicated that the meat from the Narav´e; boars was no different from sow meat. As you can imagine, that was just what I wanted to hear."
In three weeks, Greger and McIntyre obtained samples from 19 Narav´e; pigs and 11 normal boars. "We did what's called a 24-hour gonadotropin challenge," Greger explains. That is, after taking an initial blood sample, they injected a hormone that would kick-start steroid synthesis, then took another sample 24 hours later. "By stimulating the pathway we could measure hormone levels before and after and see if they were being produced normally."
They would have stayed longer, and taken more samples, except that one day McIntyre began to notice a mysterious swelling in his ankle. Before long his entire leg had started to balloon. On the stern advice of local doctors, and fearing among other things the disease that leads to elephantiasis, McIntyre and Greger quickly packed up and headed home.
McIntyre never did learn exactly what had happened to his leg. "Must have been an allergic reaction," he says. "It still swells after exercise." The results on the pig blood, when they finally arrived from New Zealand (where the blood had been sent because of export-import restrictions) in June of '96, were more conclusive.
"The results showed very low levels of 17-hydroxy-pregnenolone, or 17OHP5," Greger says. 17OHP5 is a hormone that occurs early in the testosterone pathway. Its appearance is governed by an enzyme known as cytochrome P450c17, or c17. "So it looks like c17 is what's defective in these pigs.
Greger and McIntyre plan to return to Vanuatu to sample the Narav´e; populations on other islands. "I'd like to go back and buy some pigs, take them to Port Vila—there's an agricultural college there—and set up some controlled experiments," Greger says. "And I'd like to get the students there involved. It would be nice to work out something that's mutually beneficial."
He suspects that molecular studies on the way these unusual animals make (or don't make) steroids may provide insight into some bigger questions than boar taint.
"I think these pigs can tell us something about how males become males."
Douglas Leigh Greger, M.S., is a Ph.D. student in the department of dairy and animal science, College of Agricultural Sciences, 305 Henning Building, University Park, PA 16802; 814-863-0723. His advisor, Daniel R. Hagen, Ph.D., is professor of dairy and animal science. The work described above was funded by the Perez Trading Company, Florida.