Hm...
1) we would have to compete with them for food
2) we'd have to run like h if we saw a predator
3) we'd have much more different cities
4) some inventions might not have been invented
5) some modern species would be extinct, or not exist
It was advantageously located near the coast and other settlements.
They offered defensive positions and safety to the people. They were also where the Lord lived and where the lord was is where the money was. Thus trade and economic prosperity happened around the castle. Many trades were needed to support the lord and his castle. The lords army had to be equipped and fed. Thus markets and tradesmen were needed to support the lord and his castle.
