There's research on resilience and post traumatic growth (I can never remember authors to reference) that finds that people experience an average of 8 traumatic events in their life. Only about 8% of people go on to develop PTSD. Most people are able to process, learn and grow from trauma - so there are long term effects but not necessarily negative. And those with PTSD can recover from their trauma with a bit more specific focused help and resources. I'd imagine that before therapists, that shamans, priests, and the community were pivotal in healing trauma. Trauma has always been around. It's a fact of life.