By DREW CALVERT

On my final day in Malaysia I visited the Great Cave near the town of Niah, site of the oldest human remains in all of Southeast Asia.  To get there, I took a bus from Miri, a city not far from the Brunei border, which brought me close to the main entrance of an unceremonious national park.  At the museum, I glanced through photos of Englishmen joylessly separating ceramic from bone, and I studied brochures on the local economy, which runs on bird’s nests and guano.  Then I walked through a rainforest thick with cicadas until I reached the mouth of the cave, which looked like a secret airport hangar or a decommissioned gateway to hell.  Armed with a flashlight and an outdated map, I followed a mossy path through the darkness and breathed in the prehistoric funk.  By sunset, I found myself back at the entrance, where swiftlets and bats converged on each other in a giant black cloud above my head.