It all starts with the chances of your parents’ meeting. Your dad was maybe walking one day and out of 200 million women, he bumped into your mum. There is a 10 percent chance they exchanged conversations. 10 percent says they went on a second date. Another 10 percent to go on another one, and another, and another. Sparks flew, butterflies in the belly, your dad must have swept your mum off her feet. Yadda yadda yadda. Soon, love grows. But love doesn’t always work out the way we thought it would. They would have broken up after a big fight. Or dated long enough to soon grow tired of each other. The chances of your parents staying together long enough to have kids are 1 in 2,000. So far, the chances of you existing are 1 in 40 million.
It’s only getting started. During the years you could have been born. your dad has produced over 4 trillion sperm cells. Your mum, on the other hand, has about 100,000 eggs in her lifetime. They would have dated other people before meeting, or the other’s firsts. Yet, here they are together. That means that the odds of the one egg and the one sperm meet to later produce you is 1 in 400 quadrillions.
Are you still there? It’s not over yet. The odds of you being here – on Earth, at this time -meant that before you are 4 billion years of an unbroken chain of many, many generations that lived long enough to reproduce. Grandpa Philipp could have been hunting one night and never would have returned to his newly wedded wife. That’s 1 in 10^45,000.
But of course, remember that that one egg had to meet that one sperm. The odds of you now is 1 in 10^2,685,000.
Your mother could have turned left and never would have bumped into your father. Or he could have been 1 second too early or too late. Or many years down the line they would have met, only to have your father have his wife beside him. Or say, they fell in love. At a seemingly perfect time. Their careers are blossoming, social life pounding and energies ecstatic and wild. Only to have learned he’s moving away but she’s not.
The odds of you, here, now, is basically zero.
The odds of you and I? Incomprehensible.