This might be a good time to stop and think about how pleased we should all be with ourselves as human beings for the progress we continue to make here on Earth.
We've found cures for diseases that enable us to live 23 years longer than our grandparents. We grow food enough to feed ourselves without having to go into the woods to pick it or shoot it.
A thousand years ago, most people didn't go anywhere because they had to walk. Now we travel everywhere on wheels, and around the world on wings.
The most progress we've made, though, is in the ways we've invented to kill each other.
When one caveman wanted to kill another, he had to get close enough to hit him with a club.
The sling is what made it possible for David to kill Goliath by hitting him in the head with a rock from 20 feet away.
For hundreds of years, men killed each other with blades of steel, sharp knives and swords. Metal suits were in vogue.
The bow and arrow was a favorite of medieval times.
The invention of gunpowder was the single biggest help to people killing each other. They packed the explosive powder in one end of a tube, stuffed a metal ball down the other, then lit the powder to blow it out.
They improved the cannon by filling a hollow steel ball with powder so it exploded and killed more people when it hit them.
In our Civil War, people were killed one at a time by a rifle bullet.
The handheld gun has been a more popular murder weapon at peace than at war.
World War I brought the first use of chemical weapons like mustard gas.
We've got airplanes and tanks as weapons. Tanks didn't always work out, though.
There was a proliferation of new weapons for World War II. Bombers that could wipe out a whole city, guided missiles and then, more recently, nuclear submarines.
The United States used the most effective way of killing a lot of people quickly ever devised when we got back at the Japanese for Pearl Harbor. We killed 100,000 of them in no time at all with two atomic bombs.
Poof and they were gone.
Our military leaders assure us that our weapons now are even better.
Men and women on Earth as we know them are maybe 100,000 years old, nothing compared to the millions of years of Earth's history without them.
If we continue our progress inventing weapons capable of wiping ourselves out, Earth could end up without people again.