You can trace what caused World War II all the way back to World War I

The Germans were treated very badly after World war I and this caused World War II in retrospect. This is why the United Nations was started so the Japanese and Germans especially would be better treated so we wouldn't accidentally create World war III.

How can we trace this though?

I think you have to look at overpopulation in Asia first and 2nd you have to think about global Warming and Global Climate Change and even the fires in Australia as a part of all this.

When you have 33 people dying on Easter Sunday from Tornadoes in the U.S. you know something is wrong like when all the fires burned down so much of Australia recently.

So, one way or another it looks like the human race is getting thinned out like so many times before since at least around 500 BC worldwide.