While the comic (as we know it today) might be a fairly 20th century invention, comics have existed for thousands of years. Whether in ancient Egyptian hieroglyphics, cave paintings in Lascaux, France, or Victorian England, the comic has continued to evolve. In today's society, frames, gutters, word bubbles, icons, symbols, etc. have become the basis for constructing comics.
While the basic construction is the same, comics have evolved from their cave painting ancestors. Cave paintings and early "comics" were focused on depicting rituals, hunts, etc. However, what these early comics and modern comics have in common is the very basis of Scott McCloud's definition of comics: "juxtaposed pictorial[s] and other images in deliberate sequence." In addition to the very definition of the comic medium, the idea of preserving history in words and pictures has continued.
Each comic demonstrates a different segment of history: social, economic, cultural, etc. Whether it be drug use in the 1970's (Green Lantern and Green Arrow), racial inequality in the 60's, greed in the 30's, or hunting Mammoths in prehistoric time, comics have always depicted some aspect of life that becomes part of a written history.
Another change in the evolution of comics is the interaction between words and pictures. In early comics, there were no words, and when they were included in later centuries, the two were separate pieces. In modern comics, the words and pictures are interchangeable. Comics live and die off of the story and art. Without great art, a comic is a novel. Without a great story, the comic is a picture book. Comics artists and writers maximize meaning by deciding the role of a word bubble or an onomatopoeia in electric colors and designs, or the size and shape of a panel, or the construction of the closure between panels. Comics have become as much about the gutter as they have about the actual panels themselves.