The gangsters walked into the bar, grabbed her by the arm and started dragging her up the stairs toward a private room where hostesses were taken to be raped. She quickly realized she was in real danger. It took the combined efforts of the bar owners, bouncers and hostesses to save her.

The incident demonstrated the dangerous nature of the project that Zheng Tiantian, at the time a PhD student at Yale University studying anthropology, had embarked upon in 2000: two years of embedded fieldwork at a karaoke bar in the crime-plagued, red-light district of a city in China.

Her book Red Lights: The Lives of Sex Workers in Postsocialist China, published in 2009, depicts the world of karaoke hostesses in China, where prostitution is intertwined with rural-urban migration. Zheng declined to disclose the name of the city for fear it would bring trouble to the sex workers she mentions in her book.

Zheng, now a professor of anthropology at State University of New York, Cortland, studies gender, sex, class, migration, and social and cultural transformation in China. As a graduate student, she reexamined her ideas on women's rights, prompting her to look deeper at the issue. She told the Global Times in an e-mail interview that working and living with the hostesses changed her views of these women.

"These experiences to me are a brutal awakening to the ways in which women contrive with their bodies to redistribute the wealth and power mostly controlled by men," she said. "They reveal to me the paradoxical complicity and resistance of women in reproducing and counteracting the power hierarchy between men and women."

Zheng believes sex workers are no different from people employed in other service sectors. "They occupy a space between complete victims and liberated women … Customers and sex workers can mutually empower and exploit each other."

Hostess from Yale

With the help of local officials, Zheng found a bar whose owners agreed to ensure her safety while she conducted her research disguised as a karaoke hostess.

At first, then 28-year-old Zheng's presence was greeted coldly. The hostesses at the bar did not believe that a PhD student from Yale would want to write a book about them. They called her "glasses" and "college girl" to distance her from their circle and laughed at her inability to understand their sex talk and jokes.

"Why do you study us little people? Why don't you study professional urban women?" they asked her, which Zheng believes elucidated the core of the hostesses' self-image: They see themselves as "small fries" as opposed to professional urban women.

In order to deepen her understanding of their lives, Zheng tried to put herself into their shoes. She lived closely with the hostesses in a room that lacked bathing facilities. Together they got up around noon, ordered take-out, went shopping, worked from 6 pm until midnight, and went to bed around 3 am.

Zheng wore strong make-up and dressed in flashy clothing. Her mother, who lived in the same city but knew nothing about her research project, complained that she dressed like a hooker.

One night, Zheng drank so much that she became very sick and couldn't stop vomiting. The other hostesses took care of her and cried with her. That night, she said, they connected with her on a more personal level, and she felt she was finally accepted by these women.

"Between sweetness and bitterness, we shared countless such moments and they bonded us together as time went by," she wrote in her book. 

As a hostess, Zheng tried to make herself "invisible" to customers. She dressed to attract less attention - in longer skirts and solemn colors - and she wore glasses. In the words of one hostess, she looked like a "real nerd."

However, despite her efforts, some customers still chose her. Following other hostesses' advice on "how to thwart customers' sexual advances," she managed to save herself from trouble most of the time.

During those two years, Zheng witnessed the pain that the hostesses went through, and they would often cry from their injuries. Their legs, arms and breasts were black and blue from the hard pinches of clients, bar owners and security guards. In the city, bodies of hostesses were found murdered on the street. Sometimes police couldn't identify them.

Zheng once asked the mother of her closest hostess friend if she worried about her daughter's safety. She said that once, she didn't hear from her daughter for three months and thought she was dead. At one point, Yale, concerned about her safety, brought her back from the field.

Her book has drawn much scholarly interest in the US, and China's public health agencies have requested information from her.

In 2004, Zheng returned to the city and was told that hostesses were now required to be naked while singing and dancing with customers, a new tactic to boost business.

"It shows us the most serious challenge to the hostesses, whose job is not just to exploit their bodies for wealth but also to hang on to some shred of dignity," she wrote.

New debate on oldest profession

Activist Ye Haiyan, also known as Hooligan Swallow, also brought attention to the plight of sex workers in 2012. She blogged about her experience giving free sex to migrant workers in a brothel in Guangxi Zhuang Autonomous Region for two days.

The World Health Organization has estimated that China has about 4 million sex workers. As prostitution is illegal in China, Ye is calling for its legalization to keep sex workers safe and protect public health.

"Hostesses fall into a gray area - the law does not clearly identify them as either illegal or legal," she wrote.

Zheng also agrees that decriminalizing prostitution is necessary to better protect these women.

"Worldwide, sex workers' rights movements argue that sex work is a legitimate form of labor and that sex workers need rights, not rescue," she said. "Decriminalization is necessary to diminish the violence."