A UCLA study found a connection between how quickly the brain ages and the bacteria and chemical byproducts found in the gut, offering a fresh clue into what drives brain aging long before symptoms appear.

New research finds there is no substitute for real-world observations, but that — under the right circumstances — AI-generated images can be used to improve the performance of computer models used for species identification and biodiversity monitoring.

The Ice Age woolly rhinoceros may have owed much of its evolutionary success not to the frozen Siberian landscapes with which it is most closely associated, but to the more temperate regions of Eurasia, a sweeping new analysis of ancient DNA and Pleistocene habitats suggests. The findings highlight the importance of studying ancient DNA from southern regions, where genetic diversity may have originated and persisted but has been overlooked because DNA preservation is generally better in northern Eurasia. The woolly rhinoceros was one of the Ice Age’s iconic species, inhabiting Eurasia for more than 100,000 years until its extinction near the beginning of the Holocene. Despite surviving the glacial and interglacial climate cycles that characterized the Pleistocene for thousands of years, it’s still relatively unknown how these drastic environmental changes shaped the animal’s evolution, population, and eventual decline. Ancient genomic studies have revealed previously unknown genetic diversity, but greatly limited genomic records – exclusively from the Late Pleistocene Northeastern Siberia – leave major gaps in the understanding of the species’ population structure, migration, and genetic history across much of their range, particularly in mid-latitude Eurasia. Xiao-Le Lei and colleagues address these gaps by screening 183 woolly rhinoceros fossils from across Eurasia and recovering 29 mitochondrial genomes and 14 nuclear genomes from specimens spanning East Asia, the Altai region, and Europe, and combined these data with previously published genomes from woolly rhinoceroses and related species. Using several complementary dating methods, Lei et al. placed the fossils across multiple stages of the Ice Age, extending back more than 200,000 years. The authors also modeled woolly rhinoceros habitat across the past 500,000 years using fossil records and climate data on Pleistocene temperature, rainfall, and food availability to evaluate how long-term environmental shifts affected changes in the rhinoceros’s population history and genetic structure. The findings show that woolly rhinoceros populations had a complex genetic history shaped by climate and shifting habitats. Mitochondrial evidence shows that major maternal lineages emerged roughly 460,000 years ago, with a clear genetic divide between East and West Eurasia and the greatest diversity concentrated in mid-latitude regions rather than Siberia. Moreover, the genetic data suggest that the rhinoceros’s greatest genetic diversity arose in mid-latitude East Asia, rather than high-latitude Siberia, while the Altai region served as a long-term refugium and dispersal hub during interglacial periods. The findings also revealed evidence of gene flow between woolly and Merck’s rhinoceros, indicating that the two species interbred during the Late Pleistocene.

This summary was updated at 15:30 US ET on Tuesday, 09/08/26