Core Viewpoint - The evolution of horses spans 55 million years, transitioning from ancient ancestors to modern horses, with significant implications for cultural and historical narratives [1] Group 1: Evolutionary Stages - The evolutionary history of horses is divided into five main stages: ancestral horses, late Eocene horses, ancient grassland horses, late Miocene horses, and modern true horses [1] - Ancestral horses were small, comparable in size to dogs, and adapted to forest environments during the early Eocene [1] - Climate changes prompted horses to evolve towards larger sizes and faster running capabilities suitable for grassland environments [1] Group 2: Fossil Resources and Research - China is highlighted as a key region for studying the evolution and dispersal of horses due to its rich fossil resources of true horses, the direct ancestors of modern horses [1] - Currently, there are only seven existing species of horses, with wild species facing threats and classified as near threatened to critically endangered [1] Group 3: Human Interaction and Cultural Significance - The domestication of horses began approximately 5,500 years ago, marking a significant partnership between humans and horses in various aspects of life [1] - Horses have played a vital role in human history, symbolizing loyalty and courage, and are embedded in numerous cultural expressions and idioms [1] - The future relationship between horses and humans is expected to continue evolving, contributing to shared narratives and experiences [1]

Core Viewpoint - The research highlights the genetic basis of horse domestication, emphasizing the role of specific genes in enhancing horse behavior and physical traits that facilitated their integration into human society, particularly in transportation and warfare [4][9]. Group 1: Historical Context - Horses have played a crucial role in human history, transforming transportation and warfare since their domestication, which dates back to around the mid-3rd millennium BC in the steppes of the Don and Volga rivers [4]. - The study published in Science reveals that genetic mutations related to behavior and physical structure were pivotal in the domestication of horses, enabling them to assist humans in rapid movement [4][9]. Group 2: Genetic Findings - The research team identified selection signals in 266 genetic markers associated with key traits, particularly focusing on the ZFPM1 gene, which influences anxiety behavior, and the GSDMC gene, linked to physical structure [8][9]. - The ZFPM1 gene showed positive selection signals approximately 5,000 years ago, indicating that temperament and trainability were among the earliest steps in horse domestication [8]. - The GSDMC gene underwent strong selection starting around 4,750 years ago, leading to physical adaptations that made horses suitable for riding, thus playing a decisive role in the rise of mounted civilizations [8][9].