I sometimes ponder how many things had to happen in order for me to exist. There are countless things that happen on this planet every day, of course, but some of these things absolutely positively had to happen in order for me (and you) to exist. In this post, I will discuss a few of these contingencies that had to happen in order for you to be reading this post. This is a tale permeated with sex and violence.

The correct egg needed to meet the correct sperm or else we wouldn’t have been born. Given that there are more than 40 million sperm in each ejaculation, it was almost mathematically impossible for the “correct” sperm to get to my mother’s egg on the “correct” day.

But for that sperm and egg to have met, my parents needed to meet. And they needed to court each other in such a way that they, to at least some minimal degree, liked each other on the “correct” evening. But my parents might not have met at all–they each were on

their on convoluted paths through life.  Even under the assumption that they would meet, they might not have had sex at the “correct” time. Their parents and their parents had to meet and have sex at the “correct” too. The complexity of this inverted procreational pyramid boggles the mind; if you go back merely 10 generations, that means that 1,024 couples needed to meet, have the willingness to become naked and also have penis in vagina sex at the precisely “correct” time for me (or you) to exist.

But that is only one category of challenges out of countless additional things that had to happen for me to be writing this and you to be reading this. Each of our ancestors had to survive every day of their lives, and survival was not easy for most people in past generations. In the 1800s, the average person only lived for 30 or 40 years. Many women died in childbirth (more than 1% of births in the 1800s) and many babies did not survive to become children (my grandmother was one of 13 children, 8 of whom died as babies in the late 1800s).

Each of our ancestors needed to survive up to the point where they created the next generation that led to me (and you). How many of those people almost died of accidents? How many of their parents moved to a new city (or almost didn’t move) which would have messed with this path to me (and you)? And after giving birth to the baby of the next generation, those parents (or someone else, filling in) needed to make sure that that baby was fed and nurtured every day, for thousands of days, so that baby would procreate at the precise “correct” time with the precise “correct” person to keep the path to me (and you) intact.

This need to keep the path intact was humorously illustrated by the movie, “Back to the Future,” where Marty McFly, sent back in time, almost extinguished his own existence when the young woman who was not yet his mother had a romantic crush on him.

But this inverted procreational pyramid is only one of many trillions of conditions precedent to your existence.  Many quadrillions of additional things needed to happen for us to exist, so many conditions precedent that if we were transported back in time to only 100 million years ago and asked to calculate the odds of either of us being born, the answer would have clearly been a big fat zero. From that vantage point 100 million years ago, there were no human animals. There weren’t even any primates yet.  Sure, we would have perhaps calculated that there was some chance that some sentient beings might someday exist, but the odds that that either of us would have been among those beings would have been zero.

What led me to think about the unlikelihood of my existence?  In order for me to exist, the dinosaurs, who once dominated the planet, needed to be substantially cleared away to make room for mammals to flourish.  In “The Day the Dinosaurs Died,” Douglas Preston describes something that all of should put into our scrap books. It happened 66 millions years ago and it wasn’t subtle. A asteroid bigger than Manhattan slammed into the Earth. Preston describes the event in vivid terms:

Within two minutes of slamming into Earth, the asteroid, which was at least six miles wide, had gouged a crater about eighteen miles deep and lofted twenty-five trillion metric tons of debris into the atmosphere … When Earth’s crust rebounded, a peak higher than Mt. Everest briefly rose up. The energy released was more than that of a billion Hiroshima bombs, but the blast looked nothing like a nuclear explosion, with its signature mushroom cloud. Instead, the initial blowout formed a “rooster tail,” a gigantic jet of molten material, which exited the atmosphere, some of it fanning out over North America. Much of the material was several times hotter than the surface of the sun, and it set fire to everything within a thousand miles … Some of the ejecta escaped Earth’s gravitational pull and went into irregular orbits around the sun. Over millions of years, bits of it found their way to other planets and moons in the solar system. Mars was eventually strewn with the debris—just as pieces of Mars, knocked aloft by ancient asteroid impacts, have been found on Earth. A 2013 study in the journal Astrobiology estimated that tens of thousands of pounds of impact rubble may have landed on Titan, a moon of Saturn, and on Europa and Callisto, which orbit Jupiter.

I highly recommend reading Preston’s article. It will give you a front row seat to this event and the effect it had our planet. As you read it, it might seem simply like an incredible story, but that asteroid had your name on it, in a very good way for you. If it hadn’t decimated our planet, large mammals, including human animals, wouldn’t have thrived.  That’s according to paleontologist Thomas Richard Holtz. That is also the opinion of many scientists, including Robert, DePalma, a scientist whose discovery of a KT boundary fossil field was featured in the above article in The New Yorker. DePalma observes: “We can trace our origins back to that event.”

In sum you and I would never have existed, except for the mass extinction caused by that asteroid . . . and trillions of other things totally out of our control.

I love the story of the red thread, but don’t know that that thread has ever been stretched this far, however.