Despite a 30% increase in Solar luminosity, Earth's glacial record appears to become more frequent over geological time. At least two of the three major Precambrian glacial intervals were exceptionally intense, with solid evidence for widespread sea ice on or near the equator, well within the “Snowball Earth” zone produced by ice-albedo runaway. The first low-latitude glaciation in the early Paleoproterozoic (the Makganyene in South Africa) is associated intimately with the first solid evidence of global oxygenation, including the world's largest sedimentary manganese deposit. Subsequent low-latitude glaciations during the Cryogenian period of the Neoproterozoic are also associated with progressive oxygenation, and these young Precambrian ice ages coincide with the time when basal animal phyla were diversifying. However, specifically testing hypotheses of cause-and-effect between Earth's Neoproterozoic biosphere and glaciation is complicated because large and rapid True Polar Wander events punctuated Neoproterozoic time and even may have extended sporadically into the Cretaceous.