Consider...

What are the chances of...

...walking into a Las Vegas casino, putting a dollar coin into a slot machine and winning the house jackpot... not just once, but THIRTEEN TIMES IN A ROW???

Every few tens of millions of years, the Earth passes through the plane of the galaxy during which it is highly likely to be hit repeatedly by huge asteroids, each capable of wiping out all life above bacteria.

The odds of life of any scale surviving to now are the same as walking into the casino and winning 13 times, first roll, on thirteen slot machines in sequence.

This does therefore give the impresson that there really is an ancient alien planetary defence system automatically protecting our back, sitting to the East of othe Ural Mountains.