Two scientific papers published this week got me thinking about the end of the world as we know it. The first, published in Science Advances, involves an asteroid impact half a billion years ago. The second paper, published in the journal Life, has to do with naked mole-rats and their latent potential for increased intelligence. At first glance these subjects seem to have nothing in common, but they do.
The Life paper resulted from a collaboration between Rochelle Buffenstein and myself after we met at a conference in Brazil last year. The article describes the astonishing abilities of naked mole-rats, mammals who live in underground burrows and engage in what amounts to sustainable farming practices. These intriguing creatures are long-lived and highly sanitary, and they show signs of intelligence, including playfulness and sociability. They live in burrows of about 100-150 individuals—similar to the size of early human villages in the Neolithic age. Their sociability is advanced; they are “eusocial,” meaning they have a social structure similar to bees, ants, and termites, and are ruled by a queen.
The second paper, led by Birger Schmitz from Lund University in Sweden, claims that the break-up of a 150-kilometer-wide asteroid 466 million years ago caused a major upheaval in Earth’s biosphere. The most immediate result of the impact was an immense input of dust into the terrestrial atmosphere, which shaded the Sun, causing a global drop in temperature and resulting in an ice age and falling sea levels. That must have caused lots of stress on the biosphere, but eventually life bounced back. In fact, it came back even stronger in what is known as the Great Ordovician Biodiversification Event. Details still have to be worked out, but the study points to the effect extraterrestrial events can have on a planet’s biosphere.
Not that we didn’t know that before. The Chicxulub impact about 65 million years ago caused non-avian dinosaurs to become extinct, and killed most of our planet’s surface life. But some nocturnal rodent-like species, about the size of young rats, survived, ringing in the age of mammals.
It’s not far-fetched to say that an event of this magnitude could happen any time, even today. NASA Administrator Jim Bridenstine recently argued that we need to take the threat of impacts more seriously and renew efforts to track Earth-threatening asteroids. And with good reason. Just last century, a meteorite exploding over Tunguska in Siberia in 1908 showed how devastating even modest-size impacts can be. It leveled about 2,000 square kilometers of forest, and if such an explosion happened over North America’s East Coast or central Europe today, the casualties could number in the millions.
If a biosphere-changing impact occurs again—one that eradicates most of our planet’s surface life—naked mole-rats might have the ability to take over from humans as the most advanced species on Earth, just as rat-size rodents took over from the dinosaurs after the Yucatan impact 65 million years ago. Of course, it’s challenging to say exactly what would happen to our planet after such a catastrophe, and even more speculative to predict the future course of evolution. But naked mole-rats have characteristics that would make them suitable to cope with such a calamity. Today they are strictly herbivorous, but if they became less picky and developed a taste for meat, dead or alive, then perhaps…
Either way, naked mole-rats allow us to contemplate the fate of any macroscopic organism on a habitable world whose surface becomes uninhabitable at some point in its natural history, after other animal-like organisms have already evolved. They also invite us to think about a very different type of social world, in which our type of individualism—which I personally like a lot!—would be far less important.