Science

Lessons From a Primate Who Survived the Worst Day on Earth

66 million years ago, when an asteroid wiped out the dinosaurs, somehow our ancestors were OK.

A dinosaur advances upon a small Purgatorius as an asteroid plunges downward.
Photo illustration by Slate. Photos by Getty Images Plus and Wikipedia.

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A few years ago, I signed a deal to write a book about how life on Earth was almost wiped out 66 million years ago. The end of the world felt like a distant, fascinating topic that I wanted to understand from the inside out. But it wasn’t long after I started writing the story that I hunkered down at home with my girlfriend, our cats, and our German shepherd for a “two week” lockdown … that turned into two years of societal bumbling during a deadly pandemic, which also saw an extremist Christian fringe grab more and more governmental power.

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During this time, in addition to writing about the almost-end of the world, I was taking a new regiment of hormones. The woman I knew I was started to manifest in the flesh, from breasts to the painfully affirming cramps of my first period at age 38. For once in my life, I started to feel better. And then I’d read the news.

In my home state of Utah and around the nation, transphobic laws threatened everything from trans kids’ ability to be themselves to what bathrooms people like me can use. I knew it wasn’t going to end there. Now, as the Supreme Court is poised to overturn Roe, and, who knows what else next, hope feels in short supply.

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But as bad as things are and may be likely to get, I have to believe there’s a way through. That’s because my ancestors—and yours—lived through the worst catastrophe in the history of life on Earth.

On a spring day 66 million years ago, our planet went to hell. A 7-mile-wide asteroid struck our planet in what’s now the Yucatán Peninsula, immediately creating shock waves and megatsunamis that were so powerful they actually rebounded back toward the point of impact after they hit the shore. Within hours, the millions of tons of rocky debris thrown into the atmosphere started to fall back down, the friction making air temperatures rise to over 500 degrees Fahrenheit across the Earth, roasting alive any living things unlucky enough to be caught out in the open. If you could take the heat, then you’d next have to handle the cold: Years of “impact winter” followed, strangling plant life on land as well as in the seas, putting entire ecosystems on the verge of collapse.

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Yet life did, uh, find a way. Our great-great-great-great-etc.-grandmothers were among the creatures who survived.

Tracing direct ancestry through the fossil record is a fraught and sometimes impossible task, both because the record itself is incomplete and because we’re still uncovering it. There are far more rocks to inspect than there are paleontologists. But we know that our ancestors were present during the end-Cretaceous apocalypse for two reasons. First, we’re here—we are just the tip of a long evolutionary thread that goes back to Earth’s earliest life. But second, we have a smattering of fossils belonging to a little beastie that could easily curl up in the palm of your hand: Purgatorius, the earliest known primate. Even though we can’t say we’re direct descendants of Purgatorius, the fact that this mammal was a primate—the earliest member of our family—means that somewhere on Earth, our direct primate ancestors must have existed at the same time. They most likely looked like fuzzy insectivores that probably hid underground on that first awful day and survived as best as they could during the three years of dust-choked impact winter.

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If you’re a little surprised that there were little shrewlike primates scampering through the trees during the same time as T. rex, I don’t blame you. Their story is rarely told. We often divvy up the history of life and Earth so it’s clean and neat, everything in its proper box. For over a hundred million years, there was a great age of reptiles. Following that, there began our present age of mammals. Or so the classic story goes. But, as I explore in my new book—The Last Days of the Dinosaurs, the product of all those thoughts I gestated in lockdown—this isn’t exactly how things went. The first mammals evolved alongside the earliest dinosaurs and other imposing saurians, thriving for tens of millions of years at small size. And they weren’t just meek insectivores shivering in the shadow of the dinosaurs. There were beaverlike mammals that ate fish, mammals that evolved to rip into termite nests like aardvarks, prehistoric equivalents of flying squirrels, badgerlike mammals that munched baby dinosaurs, and, by the very end of the Cretaceous, tiny primates.

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In rocks of the same age as those that entomb the very last Triceratops, paleontologists have found the tiny bones and teeth of Purgatorius. No one has yet uncovered a complete skeleton, but, from the available parts, experts hypothesize that this mammal looked something like a modern-day tree shrew and that it nabbed beetles and other crunchy morsels in the forests of Montana circa 66 million years ago. Fossils of Purgatorius have also been found in rocks dating to the time period directly following the Cretaceous—the Paleocene—when the only dinosaurs left were birds. When the great dinosaurs perished, this teensy primate managed to survive.

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We can only presume how Purgatorius made it through. It couldn’t have been about body size alone. The disaster at the end of the Cretaceous wiped out about 75 percent of known Cretaceous species. Even among kinds of organisms that we think of as “survivors”—the lizards, the birds, the mammals—there were still losses. What’s perplexing is the fact that paleontologists think Purgatorius primarily lived in the trees. When the air is so hot that it’s essentially broiling any plant or animal out in the open, tucking away inside a tree hole isn’t going to help.

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The answer might be found underground. In the terrestrial habitats where Purgatorius lived, the safest places to be were beneath the surface of freshwater lakes and rivers or belowground in burrows. Both areas were capable of shielding organisms from the heat above during that first day after impact. Even if Purgatorius didn’t burrow themselves, it’s entirely possible that enough of their species found abandoned burrows or occupants who weren’t too stubborn about sharing. They could have hidden out for a few hours until the heat died down.

The following years would have presented plenty more survival challenges. Geochemical compounds thrown into the atmosphere by the impact reflected a great deal of sunlight away from Earth’s surface, as soot and dust blocked the essential sunlight plants needed. Survival was not assured. But somehow the primates made it through, when they could have so easily been wiped out. The fact we are here to look back and reflect is a testament to the resilience of little insect-munching mammals.

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What’s more, our history as primates isn’t a coda to the world’s worst mass extinction. Our story is directly entwined with an unprecedented disaster that was impossible to prepare for, and that likely pressed a great deal of life on Earth to the limits of survival.

When the bad news seems to keep getting worse by the day, I try to remember those little fluff balls that managed to hang on during a time of razor-toothed monsters, as well as the cataclysm that toppled the saurians. I’ve tried to snug down into burrows of my own, like couch time with my family; the animals drape themselves around my girlfriend and me to snooze. I love happily chatting with the baristas, tattoo artists, piercers, dommes, and other people in Salt Lake City’s counterculture, people who already know how to find joy under a restrictive regime. I’ve found a soothing squeeze in various rope ties I’ve taught myself during lockdown, part of a self-driven BDSM crash course that helps me find a calmer headspace and stop running around like a frantic Cretaceous primate. It’s a way to be present in the body that’s changed so much during these years, a way to feel safe in a body that some would legislate out of existence.

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There won’t be any asteroid strike that’ll sweep away our oppressors, but, reflecting on found family and the empathy shared by those who are rightfully fearful of what’s coming next, I do have hope that our society can become kinder, and enthusiastically queerer, than it is now. Perhaps we’ll need to burrow down for a little while and find refuge as the worst unfolds. But the dark days can’t last forever. Someday, like twitchy little primates, we’ll be able to survive through this time of heat and shock waves to thrive in a world free of cold-blooded rule.

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