Final answer:
Antecedents of behavioral complexity are rooted in the early organization of primordial systems and have evolved into complex adaptive behaviors observed in higher organisms, especially humans.
Step-by-step explanation:
The antecedents of behavioral complexity appear first in primordial systems like the ocean, where the earliest forms of life organized themselves into complex adaptive systems. Over geological time, these systems evolved, resulting in a diverse range of biological organisms with increasingly sophisticated behaviors. Simple learned behaviors such as habituation and imprinting are seen in lower animals, indicating an innate component that allows organisms to adapt, although true behavioral complexity, which includes the ability to learn from experience and the environment, tends to be more developed in higher animals and most pronounced in humans. A notable point in evolutionary history is early species that found advantages in behaviors like migration, subsequently teaching these behaviors to their offspring, demonstrating the initial stages of complex adaptive behaviors.