Final answer:
Scientists before the 1700s believed that physiology was based on theories like the four temperaments associated with body fluids and phrenology.
Step-by-step explanation:
One theory that was popular during the ancient Greek era was the belief that personality traits and behaviors were based on four separate temperaments associated with four fluids of the body. Another theory that emerged in the 19th century was phrenology, which aimed to understand how the mind worked by examining the size and shape of the cranium.
These theories would be proven wrong later on, but they contributed to the development of modern psychology. It's important to note that scientific knowledge evolves over time as new evidence is discovered and theories are refined. So therefore before the 1700s, scientists studying physiology believed that it was based on a variety of theories that were prevalent during different times in history.