Fear may have changed over the millennia. Back in the hunt-to-gather-stuff cave days, fear may have been easier to understand. Back then we may have hung about in the caves more during the winter months and were keen on not getting attacked, so yeah, lots of times in the caves. Grunt! "Hey, you". " go out and get some more stuff to burn before we freeze to death in here". "Hell NO! I thought I heard something out there!"
Of course today fear can be differently enabled, if I suddenly hear some random ding-dong notification on my comm device, maybe my stress levels spike a bit from that notification and I experience some irrational fear reaction and probably for no good reason. In other words, the modern world seems loaded with irrational fears of many kinds. Today the tiger is not usually waiting for us outside our doors, however, bureaucratic red tape could be waiting at our door, enough red tape to pile on stress levels and cause much discord with the body. Stress can kill. Maybe boomer gens like Tim Leary and Ram Dass with all their many notable quotables like Tim's "Turn on, Tune in, Drop out." were the prophets for a stressed-out generation?