BUENOS AIRES — Who knew that the tango used to be just a guy thing? Men danced at the brothels of Buenos Aires in the late 1800s, practicing the steps and arm movements among themselves, the story goes. The idea was to polish their moves to impress the ladies at Argentinian dances knowns as milongas. Partner dance between men and women is apparently a phenomenon that began much later.

But either the tango is returning to its origins or the world is becoming more enlightened. For the first time, four same-sex couples are competing for the coveted tango World Cup. The 11th annual Tango Buenos Aires Festival and World Cup features three teams of men and one pair of women. It is apparently a reflection of what has been happening for some time now at the milongas.

During this week’s qualifying rounds, Juan Pablo Ramírez and his partner Daniel Arroyo were among the first teams to dance. The challenge, says Ramírez, is not only to reach the highest level, but also to demonstrate that it really does, as the saying goes, take two to tango. “And it doesn’t matter if those two are two women, two men, or a man and a woman,” he says.

He is Argentine, and Arroyo is Venezuelan. Arroyo came to Buenos Aires just to try it out, to see what it was like to live the tango lifestyle in the city where you can almost breathe it. Eduardo Arquimbau, an expert dancer who has taught for more than 50 years, says “the tango is danced like nowhere else in the world” in Buenos Aires.

Arroyo came just to watch the event last year. He met Ramírez at one of the dances, and they stayed in touch. In February, he returned knowing that they would dance together again. They started as friends and ultimately became lovers, but now they are dancing again just as friends. “The tango is very emotional,” Arroyo says. “Romance always appears between people. It’s in your blood. We went through that, but then realized it could not be. Now, we are brought together by dance.”

Ramírez says they have felt confident between rounds. “We were also well received by the audience,” he says. “The next step is to face another jury of judges. Then if we make it through, we will go onto the semi-finals. If we are successful there, we will get to the finals in the Dance Floor category.”

This time around they are both participating dressed in suits, but if they make it to the finals, they will take it up a notch. “We’re thinking about appearing more as we feel, more androgynous with heels or makeup,” Ramírez says enthusiastically. Heels are fundamental because “it changes the axis of the body and the way you do the steps when it is time to dance.”

The ladies of the Tango World Cup have the opposite consideration. “I dance in heels,” says Lucía Christe, dance partner to Marlene Heyman. “We both want to dance in shoes later on, so we need to practice.”

Both women are Argentine and have been friends for seven years. They have been dance partners for a year now. “We have fun,” Heyman says. Christe says there was a lot of anxiety at their debut this week but also a lot of joy. “What we want most is to connect and enjoy it like we do at the milongas.”