The climate in the barast world is also somewhat cooler, because of the lack of greenhouse gases compared to the gliksins' Earth. Barasts are not as heat-tolerant as gliksins, probably because they evolved on a cooler Earth and also due to their greater muscle mass. As a result, tropical regions of their Earth are just as underpopulated as the polar regions on the gliksins' Earth. A significant story feature is the state of the Earth's magnetic field. In the barast world a reversal of polarity happened shortly before the story starts and caused no noticeable harm to the barasts. As to why the pole reversals are off by several years, it is ascribed to random small differences over the intervening 40,000 years. In the gliksin world it is happening as the stories take place; this has an effect on the minds of gliksins, whose brain structures are different from the barasts' (see Religion).