Final answer:
Researchers looked for common traits in Stone Age paintings to understand their meaning and purpose, which could include religious rituals, hunting magic, and shamanism.
Step-by-step explanation:
The researchers looked for common traits in Stone Age paintings because they wanted to understand the meaning and purpose behind these artworks. There are several theories about the significance of the paintings, including religious or spiritual rituals, hunting magic, and shamanism. By identifying common themes and symbols across different cave art sites, researchers can gain insights into the beliefs and practices of prehistoric societies.