One can say that dominating fire was one major breakthrough. Men were already using rock tools in this age and it was an amazing breakthrough in history of man, but learning how to dominate fire was a game changer. It made them live longer, since they had a way to scare the predators, make light at night and to defrost meat.
Had a social structure similar to Egypt's pyramid structure
Well in the early 1920 there new inventions like radio so in the early twenties it was good but in the late twenties the Great Depression hit stock market crashed and people usually wrote about how bad their lives were and how they had to sell a lot of things people lost a lot of money in the stock when it crashed
He learned that the winds would make the boat move straight.