After several rotations, the chicken is put aside in favour of a glass bottle. The father raises it to the heavens as an offering to his ancestors' spirits and carefully sips the brown liquid.
I am witnessing a Mayan religious ritual for the first time, yet the bottle's shape seems familiar. Then Pepe confirms its contents: Coca-Cola.
"It is used as medicine," he says. "The Indians believe a belch expels demons and sickness." A metallic click echoes behind us as a Swiss army knife opens another bottle of the real thing.
The use of Coke is a startling adaptation. San Juan Chamula is a small village 2,300m up in the Chiapas Highlands of southern Mexico, near the border with Guatemala. Its inhabitants are mostly Tzotzil Indians - one of the largest groups of Mexico's pre-Spanish descendants, with a fierce reputation for defending traditions.
In 1994, Tzotzils took part in the New Year's Day Indian rebellion when armed rebels formed the Zapatista National Liberation Army. Local markets still sell Subcomandante Marcos dolls dressed up as the popular guerilla leader wearing a black balaclava and carrying a gun. Chamula is still a war zone today - but now the battle rages between the soft drinks companies. Adverts bombard visitors in the fight for brand loyalty from the moment you enter the village. A painted Coca-Cola bottle on a whitewashed wall promises siempre mejor. Immediately behind it, a Pepsi-sponsored billboard advises us not to take photographs during religious rituals. Stories still circulate about two American tourists who were supposedly killed after taking photographs inside Chamula's church during a ritualistic ceremony. Pepe shrugs them off as mere rumours.
Apart from English and Spanish, Pepe speaks Tzotzil, the language of his parents, and can get by in Tzeltal. As each of the 10 Chiapas tribes has its own distinctive dress and language, when Indians meet in San Cristobal's market place, they have to communicate with each other in Spanish. "It's their second language," says Pepe.
The colonial town of San Cristobal, with its cool mountain climate, is a popular resting place for tourists doing the Mayan ruins circuit on the Yucatan peninsula. It's a perfect base from which to visit Indian villages, but strangers are often treated with suspicion so hiring a local guide is advisable. Pepe Santiago was easily found at Na Bolom, the former home of the Swiss photographer and anthropologist Trudi Blom. Apart from being a charming place to stay, Na Bolom is also a research centre and an invaluable source of information on the Lacandon tribe in eastern Chiapas.
Chamula, 10km away, is one of the nearest and easiest villages to reach. Its Mayan inhabitants, descendants of one of the world's greatest civilisations, retain many of their ancestors' farming and religious traditions while the skills of Chiapas weavers are famed throughout the country.
After centuries of colonial rule in Mexico the Indians are naturally wary of Westerners and protective about their beliefs. Although the heavy presence of Catholic imagery may reflect religious conversion by the invading Spaniards, the ceremonies remain, in essence, pure Mayan.
Catholic priests were expelled from Chamula over 100 years ago and any Catholicism is now intertwined with traditional Mayan customs. Inside the 16th-century church, for example, the numerous saints are adorned with flowers and small mirrors. The mirrors are to reflect spirits back into people's bodies in case they escape during a trance.
Pepe points out seven statues of saints standing undecorated and at a distance from the others. "Those saints were responsible for Chamula's other church," he says. "But it accidentally caught fire and burnt down in the Sixties. They failed to protect it, so they have been punished." Further religious retribution took place 10 years later when several saints apparently ignored local prayers. The appropriate statues were beheaded and banished behind the nave.
Pepe offers to take myself and two other travellers to a friend's house nearby. It is a white bungalow surrounded by stacked planks of wood. A blue sign announces Salvador Lunes Collazo and his occupation: "h'ilol, traditional healer, Christ doctor." In other words, a shaman.
Salvador, a 55-year-old father of 12, is casually dressed in slacks and an open-necked shirt. A carpenter by training, he became a shaman 30 years ago after a revelatory dream. "The gods were teaching me in my sleep - about flowers and how to heal with herbs," he says, via Pepe's Tzotzil translation. "When I woke up I knew exactly what to do."
Since then Salvador has been Cham-ula's medicine man. His "surgery" is a 20ft-square spartan room. On one side is a display of traditional woven blankets and embroidered sleeveless huipils (blouses) handmade by Salvador's wife. The altar in the corner resembles a Catholic car boot sale. An assortment of crucifixes, candles, saints and fresh and plastic flowers jostle for attention on a vinyl-covered table. Each item is interspersed with pine sprigs and seasonally inappropriate Christmas decorations.
This particular shaman's abilities, however, should not be underestimated. Salvador's reputation extends throughout Mexico and Guatemala, and has even reached the United States.
"Five years ago, he cured the governor of Chiapas," says Pepe proudly, before drawing our attention to a framed photograph hanging on the wall. It shows Salvador, in suit and tie, sitting next to George Bush at the White House.
"Bush was sick in mind and spirit," says Pepe, "so the American government flew Salvador to Washington to perform a ceremony. He's going to see Clinton, too," he adds casually, "for stress."
Shamans believe sickness affects people in body and spirit so both must be healed for any cure to take place. Before people receive treatment, their energy must first be tested to see whether it is good or bad. Westerners, apparently, are particularly prone to spiritual illness. "Some people are almost dead," Sal-vador says sadly. "They need time for their spirit and soul to heal."
It was too good an opportunity to miss - especially since Salvador could spare the 10 minutes or so for an impromptu diagnostic session at the bargain price of pounds 10.
He excuses himself to prepare the ceremony and returns wearing a black woollen tunic and carrying quilon flowers, copal resin, candles and some liquor. It is pox - a local drink made from cacti - and pronounced "posh".
I sit beside him on a low chair in front of the altar and he lightly traces four un-lit candles around my body. He presses his fingertips together and chants. Every so often I recognise my name, Susan.
After taking my pulse, he crumbles some copal resin into a clay pot and, once lit, white incense fumes explode beneath my nose. Clay pots are then placed on my palms and blown, producing a hollow husky whistle. He removes a bottle from the altar, pours it over the flowers and shakes the stems gently, sprinkling drops of green, perfumed water over my body. The chanting continues.
Salvador has now entered a trance, an essential state within shamanism, where the soul is believed to leave a body to ascend to the sky or descend to the underworld. There, he will communicate with spirits, the dead and demons. I examine his face avidly. At one point Salvador looks pained and about to cry. Perhaps, I decide, he has sensed my personal problems and the reason why I am travelling around Mexico alone.
But the diagnosis refuses to indulge my fantasy. Salvador pronounces my spirit strong, good and full of life. "Your Mayan spirit animal is the tiger," Pepe says. "The same as his."
I don't recall tigers living in Central America and assume tiger is a mistranslation of jaguar - considered an important animal since pre-Columbian times and believed to be a transformed shaman or the soul-bearer of a deceased shaman.
"You will not be harmed in your travels," he adds, "and your family and work are protected since the tiger is one of the two strongest animals."
Despite this clean bill of spiritual health, I can't help feeling a little short-changed, as if a seaside fortune teller had foreseen travel, a healthy life and a wealthy husband. Worse still, another traveller undertakes the ceremony with Salvador and she, too, is declared a tiger and spiritually tiptop.
As Salvador pours out several glasses of pox to conclude the ceremony, Pepe recalls two career women from Washington DC who travelled to Chamula after hearing that Salvador had visited George Bush. "They wanted the shaman to find them a man," he says, unable to hide his mirth. Obviously some things are beyond even a shaman.
We sip the pox slowly - it strips the lining of our throats with each swallow. But it could be worse, I decide. At least we're not drinking cola. Travel notes GETTING THERE
Iberia (0171 830 0011) flies daily from London, via Madrid, to Mexico City. Fares start from pounds 538 return, mid-season. British Airways (0345 222111) operates a thrice-weekly direct service to Mexico City from Gatwick; prices start at pounds 723. Buses go to most destinations from the capital: Mexico City to San Cristobal, via Oaxaca, takes about two days and costs around pounds 2 per hour's first-class travel. Direct flights to nearby Tuxtla Gutierrez cost around pounds 95 return.
Journey Latin America (0181 747 8315) runs a 21-day "Quetzal" trip taking in San Juan Chamula and San Cristobal. Prices from pounds 1,309 per person, including flights and accommodation.
Prices at Hotel Real del Valle, in San Cristobal (fax 0052 967 80680) start at pounds 12 per night for a double room, pounds 9 for a single. Prices at the Rincon del Arco (0052 967 81568) start at pounds 16 for a single room.
British passport holders do not need a visa to visit Mexico. Mexican Tourist Office, 60-61 Trafalgar Square, London WC2N 5DS (0171 839 3177). In Mexico City, contact the tourist office on 525 9380.