Final answer:
The theory that posits evolution as a slow, steady process is known as gradualism. This contrasts with punctuated equilibrium, which suggests rapid evolutionary changes followed by long periods of stasis.
Step-by-step explanation:
The theory that all evolution is slow and proceeds at a steady rate over a long period of time is known as gradualism. This concept is contrasted with punctuated equilibrium, which posits that evolution happens in spurts, with species remaining relatively unchanged for long periods, then undergoing rapid changes due to environmental factors, such as climate change. While the fossil record supports both models to some degree, it more clearly suggests periods of stasis followed by rapid change, indicating punctuated equilibrium as a significant pattern in evolution. Nonetheless, the existence of intermediary forms suggests that gradualism also plays a role in the evolutionary process.