Oxygen isotope measurements of marine foraminiferal fossils during 1950’s-1970’s provided continuous records of glacial-interglacial cycles. These records laid the cornerstone of the Milankovitch’s astronomical theory of climate and forever changed our view of our planetary climate system. However, because the focus was essentially on the ice age cycle, low-latitude monsoonal climates was excluded. In the last two decades or so, another revolution in paleoclimatology is unfolding. Significant advances in understanding the climatic controls on oxygen isotope in atmosphere and cave environment together with landmark developments in high-precision radiometric dating techniques have propelled the cave research to the forefront of paleoclimatology. Of particular interest are new cave records from low-middle latitudes, that show another aspect of orbital climate variations, thus calling for a more comprehensive orbital theory. This presentation will also touch on the ‘100 ka problem’—one of the most vexing issues in the orbital theory that was formulated from oxygen isotope records of deep-sea cores nearly a half-century ago.