Antonyms for "most unevolved" would be "most evolved," "most advanced," "most developed," "most sophisticated," or "most refined." These terms describe a state of progression and growth, unlike "most unevolved," which implies a lack of progress or improvement. To be considered "most evolved," an individual or species has undergone significant changes, development, and maturity over time, leading to enhanced abilities and capacity for complex thought and behavior. In contrast, the concept of being "most unevolved" signifies a primitive or stagnant state, indicating a need for improvement and adaptation for survival and growth.