EarthDate

Recently, scientists discovered the fossil of a hadrosaur, a duckbilled dinosaur, which was bitten by a Tyrannosaurus. A bite on a fossil is not that unusual, but this one helped settle an argument. Over the past few decades, some paleontologists maintained that T. rex was a ferocious hunter. Newer theories pointed to his useless forelimbs, small eyes, and huge olfactory chambers. He wouldn’t have been able to grasp prey and may have had poor vision—but he would have been able to smell a rotting carcass from miles away. In other words, he was likely a scavenger. But the hadrosaur tail vertebrae in this fossil were fused together around a T. rex tooth—the wound had healed. This meant that the hadrosaur was alive when it happened, and lived on. Which strongly suggests that T. rex did in fact chase and catch it—almost. This brought up another question: given his weaknesses, how did the tyrannosaur do it? A different set of scientists analyzed the leg mechanics of T. rex for bone stress. Proponents of “T. rex the hunter” had pointed to his speed, previously estimated at over 30 miles per hour. But this new research suggests that the foot bones, carrying his 7 tons of weight, would have shattered at that pace. The tyrannosaur’s top speed was probably just 12 miles per hour. And maybe that’s why the duckbill got away—T. rex may have been an occasional hunter, but maybe not a very good one.

You may have heard that bumblebees shouldn’t be able to fly. That’s a myth actually, as any flying bumblebee will tell you. The science of their flight is now understood. But the bees hold another mystery that could affect human agriculture. Bumblebees hibernate over winter, and when they emerge in the spring, they’re hungry. But what if the plants they rely on for pollen and nectar aren’t yet producing? The bees actually force them to do it. Like their honeybee cousins, bumblebees scout their environment to identify the best flowers. Scientists noticed a strange behavior on plants that were not flowering: the bees bit a pattern of tiny holes in the leaves. Soon after, the plants bloomed—up to 1 month earlier than normal. Once they started flowering, the bees stopped biting them and started harvesting the nectar. Researchers tried to replicate the bees’ technique by making their own tiny holes in the leaves of different plants. They bloomed earlier too, but only by about a week. How the bees produced their better results is still a mystery. Perhaps they’re leaving behind a biochemical that accelerates the plants’ chemistry. If humans can figure out how they do it, it’s possible we could force crops to bloom earlier, extending growing seasons, perhaps adding another growing season in the year, thus increasing annual crop yields. Leave it to the bumblebee, that impossible flyer, to show us how to bend the laws of nature.

In another EarthDate, we talked about Challenger Deep, the deepest point in all the oceans, at almost 7 miles down. The first humans to explore it were a Swiss oceanographer and U.S. Navy Lieutenant. They built a special deepwater submarine called a bathyscaphe, and in 1960, headed for the bottom. It took them 3 hours to reach the western pool of Challenger Deep at 35,000 feet. But they stirred up so much sediment, they couldn’t see anything. That, and a worrisome crack in a window, cut their trip short. After 20 minutes, they jettisoned their ballast and began their 2-hour trip to the surface. The next visit came 50 years later, when film director James Cameron co-designed his own ultradeep submersible and captained it solo into the deeper Eastern pool, at 35,800 feet. He spent 2 hours motoring slowly around the bottom, taking photos and video, but didn’t see any creature longer than 1 inch. Recently, explorer Victor Vescovo piloted his craft slightly deeper than Cameron, now holding the world record. His scientific team then made a few more trips to the bottom, discovering a new species and gathering samples. They found small crustaceans with high concentrations of chemicals banned in the 1970’s. And, a plastic candy wrapper. A reminder that, even in places where humans can scarcely visit, our impact can be seen.

Mt. Everest, at just over 29,000 feet above sea level, may be the highest point on Earth’s surface—but what’s the lowest? Well, the deepest part of the deep sea is the Mariana Trench in the Pacific, off the island of Guam, about halfway between Japan and Australia. It’s five times as long as the Grand Canyon and more than a mile deeper than Everest is tall. And the deepest point in the trench is called Challenger Deep, nearly 36,000 feet below sea level. It’s named after the Challenger 1 and 2 exploration ships which, in the 1870’s and 1950’s, first measured Earth’s lowest point using iron weights and very, very long metal wires. Deep sea trenches like the Mariana form along tectonic plate boundaries, where plates collide and one is forced under the other, pushing down the surface of Earth in what’s called a subduction zone. No sunlight can reach this deep, so the trench is in absolute darkness. Life and the food web are very sparse, with some creatures relying on chemosynthesis—feeding on methane or sulfur. The water is near freezing, and water pressure at the bottom of Challenger Deep is 1000 times that at sea level—enough to crush the bones of humans. Of course, that didn’t stop humans from wanting to explore it. Who they were, how they did it, and what they found, we’ll talk about on another EarthDate.

In earlier episodes, you heard that trillions of viruses live peacefully, even beneficially, within each of us today. And that our ancestors battled now-extinct “fossil viruses,” which are preserved in our own genetic code. Turns out, that’s been beneficial too. For instance, viruses helped drive our evolution. 100 million years ago, proto-mammals were infected with a virus that encoded into their DNA the ability to produce syncytin, a protein that viruses use to fuse cells together so they can move between them. But these early mammals evolved to use this protein in a different way: to fuse the placenta to the uterus, allowing nutrients to pass from mother to fetus and making live birth possible. Since humans diverged from apes, our proteins have adapted frequently to viral threats, even if they’re not part of the immune response. In fact, virus interactions now make up a third of all our protein adaptations. Finally, researchers found that ancient viral DNA in our genetic code prompts a more vigorous response to new viral threats. In experiments, when they removed fossil virus DNA from a cell, its immunity was severely weakened. Restoring the viral DNA restored the immune response. While a rare few viruses have been quite harmful to humans, the vast majority—over millions of years—have helped us to become what we are and then to remain healthy.