Rats in a cage. 100 years ago the US population was less than 100 million. In my life time (born in 1967) the population of the country has doubled to 350 million. Not to mention the population of the planet has doubled in my lifetime as well.

Add to that the fact that most people who had televisions when I was born, had black and whites that provided 4 channels. Now we have the summation of all the worlds information at our fingertips and we can make content choices that only reinforce and confirm our biases. 

Let's also not forget the mass shootings known as the Civil War, WWI and WWII, which we may argue got the blood lust out of our collective systems for a time.