View Slideshow 1 of 5 At the end of practice at the Xochikalli cultural center in Mexico City, ulama ballgame players perform a brief dedication to Aztec gods. Drums rumble between the stone walls lining the court. An ancient ritual is underway. The smell of incense wafts across the concrete, as wiry men and a woman wearing leather waist wraps and headbands volley a ball back and forth. They use only their hip bone to hit it.Emmanuel Kalakot tilts his head back and blows into a conch shell horn. The sound echoes off the brick walls . . .