Why do so many people live along coastlines?

For early civilizations, the ocean was a great natural resource as it provided a stable food source. In addition, temperature differences are much more mild near the ocean compared to temperatures in the same region but farther inland. This more predictable weather made survival through hot summer days and cold winter nights easier. Also, as trade and travel became more practical as technology improved, traveling to new places via boat was also a priority for these civilizations. As this coastal towns saw more trade and commerce, these people began to move to these towns for more opportunity.