Most people don't really appreciate how simple it is today to stay in contact with their loved ones. All you have to do is take your smartphone and choose one of the numerous messaging apps. But how did people keep in touch before smartphones with face IDs and multi-megapixel cameras appeared?
Around 30,000 years ago closer to the end of the Stone Age, people lived in caves and knew nothing about iPhones. But they knew how to draw on the walls. They created a system of symbols and left these rock paintings in caves to communicate with each other. Smoke signals were a cool way of long-distance communication. In Greece, they developed a system of alphabetical smoke signals around 150 BCE!
