12,800 years ago humans had been through the cycle of ice ages several times. After wiping out the Neandertals and Denisovans and every other hominin, we had the planet to ourselves. We had art and music and technology, and our clothing was able to cope with any environment. We had to move south whenever the glaciers advanced, but we were always moving anyway.

     We were apex predators striding the continents and having mammoths and rhinos for breakfast. We knew the phases of the moon to tell us when the grunion would run and when the summer-fattened elk would move to their winter feeding grounds. We knew everything.

     And then a comet streaked over the north pole and melted all the ice and exploded in the sky. 

     The day after that first impact everybody in the world  saw this in the night sky:

     Each of the fragments eventually returned and exploded in the sky on a scale equivalent to hydrogen bombs, vaporizing everything in their vicinity. What followed was even worse. The violent explosions threw up so much dust that the Earth was plunged into a deep, prolonged darkness-—day turned into night. Plants withered in the darkness, leading to the starvation of herbivores, which in turn caused the collapse of carnivore populations. The extinction of large plant-eating animals resulted in a drastic reduction of methane, a potent greenhouse gas, which further dropped temperatures.

     This 1,200 year period, called the Younger Dryas, became a frozen nightmare just when the Ice Age itself had finally ended. The event is named for the Dryas Octopetala flower, a tundra plant found in sediment from that time.  

     Mainstream archaeology scoffs at this Comet Impact Hypothesis because no comet craters have been found from that era. The traditional explanation is that an ice barrier collapsed around Greenland or Hudson Bay as the ice age was ending and trillions of gallons of fresh water flowed into the North Atlantic Ocean and disrupted weather patterns for a millennium, destroying the ecosystem everywhere in the world.

     Archaeologists assumed it was just another blip in the long curve of ice age onsets and retreats, similar to the 500-year Little Ice Age that ended the Vikings’ colonization of Greenland.        

     But now dozens of similarly dated debris fields have been found across North America and Europe that are highly similar to the 830 square miles of forest devastated by an asteroid exploding in the atmosphere over Tunguska, Siberia, in 1908: they contain high concentrations of platinum, nanodiamonds and tiny metallic spherules that could only have been formed under extremely high temperatures and pressures. Sediments in the basins in the 12,800-year-old layers at Abu Hureyra, Syria, show evidence of massive burning.  

     The Comet Impact Hypothesis says this debris from space is what destabilized ice sheets and caused temperatures in the Northern Hemisphere to drop to about 10°C for 1,200 years.

     The Comet Impact Hypothesis suggests the Younger Dryas was caused by the same kind of event we saw in 1994 when comet Shoemaker-Levy zoomed so close to Jupiter that it broke into 21 fragments that returned in orbit two months later and crashed into the planet one by one.

      It woke humanity from our millennia of easy living as apex predators–there was something more powerful than us.

     The Ice Age was a prosperous time for humans and they didn’t need to build cities or fortresses. Humans were full-fledged intercontinental seafarers fifty thousand years ago. As the Ice Age faded and the oceans rose, humans expanded into areas where the glaciers were retreating.

     Life was good. We were all hunter/gatherers, millennia after millennia; there was no other occupation available. Then something scared us, changed us, about twelve thousand years ago. Younger Dryas was a global reset, all right, but it didn’t erase a civilization. We didn’t have civilzation yet.

     “Civilization” is what you get when people create cities. Cities leave deep archaeological remnants. We find zero of those remnants in a million years of pre-Younger-Dryas events.

     Probably it was some kind of change in our brain structure that enabled symbology. Someday as the glaciers recede we’ll find a complete frozen Neanderthal and for the first time be able to examine its brain. All we have now is bones and artifacts. Neanderthals had bigger brains, according to their skulls, but brain size doesn’t seem to be the issue. Anatomically modern human skeletons date back over 300,000 years, and until about 70,000 years ago they used the exact same set of simple hand axes as the Neandertals.

     Something in the brain changed and technology began its intense acceleration. By 40,000 years ago we’d wiped out every other lingering remnant of previous human species who could not comprehend symbols.

     We spread across the Earth and began burying our dead with grave goods. We see much evidence of spirituality in those grave goods but no evidence of belief in gods.

     That didn’t happen until after Younger Dryas forced the invention of agriculture that made food supplies so abundant that humans were able to settle down and form cities instead of roaming endlessly in search of prey, and civilization began.

     Or at least that was the accepted story until excavations began thirty years ago at Gobekli Tepe in Turkey: many circles of tall stone pillars, megaliths, intricately inscribed with symbols, erected 11,000 years ago after the end of the miniature ice-age.

     What impelled these hunter/gatherers to assemble circles of huge rocks all around the world? I like the theory that humans decided to learn about the skies after the disastrous asteroid bombardment that led to the Younger Dryas climate catastrophe.

     The earliest known indications of astronomical knowledge seem to be the circular stone monuments pointing to the dawn on solstice days that came into existence in the Neolithic age. The stone circles tracked the cycles of the sun and the moon. They were computers that foretold the seasons. They are evidence that humans were aware of the sky. Stonehenge was the Large Hadron Collider of its time.

     Gobekli Tepe proves that humans had a wide social network long before the farming revolution. They were keen observers of the sky, likely driven by a world-shattering event. The symbols on the megaliths closely track the phases of the sun and the moon and the constellations–a calendar carved to memorialize the  devastating comet strike.

     Gobekli Tepe is the earliest surviving example of complex symbols used to communicate a warning: danger can come from the sky. It was the beginning of religion: a belief in supernatural beings in the sky. Before Gobeli Tepe there is no archaeological evidence of such beliefs.

     To explain it they conjectured gods, and then the elites cited the gods to enslave the others into agricultural servitude. Or that’s what it evolved into. Myths and legends around the world portray the gods inflicting huge damage from the sky. Sodom and Gomorrah were demolished.

     These were the kind of things that humans decided should be communicated to the next generation, and that’s why so much effort went into the projects.   

      Never Forget.

     Except, they didn’t have writing, so all we can say is, forget what?