From brilliant young polymath Andrew Rader—an MIT-credentialed scientist, popular podcast host, and SpaceX mission manager—an illuminating chronicle of exploration that spotlights humans’ insatiable desire to continually push into new and uncharted territory, from civilization’s earliest days to current planning for interstellar travel.
For the first time in history, the human species has the technology to destroy itself. But having developed that power, humans are also able to leave Earth and voyage into the vastness of space. After millions of years of evolution, we’ve arrived at the point where we can settle other worlds and begin the process of becoming multi-planetary. How did we get here? What does the future hold for us?
Divided into four accessible sections, Beyond the Known examines major periods of discovery and rediscovery, from Classical Times, when Phoenicians, Persians and Greeks ventured forth; to The Age of European Exploration, which saw colonies sprout on nearly continent; to The Era of Scientific Inquiry, when researchers developed brand new tools for mapping and traveling farther; to Our Spacefaring Future, which unveils plans currently underway for settling other planets and, eventually, traveling to the stars.
A Mission Manager at SpaceX with a light, engaging voice, Andrew Rader is at the forefront of space exploration. As a gifted historian, Rader, who has won global acclaim for his stunning breadth of knowledge, is singularly positioned to reveal the story of human exploration that is also the story of scientific achievement. Told with an infectious zeal for traveling beyond the known, Beyond the Known illuminates how very human it is to emerge from the cave and walk toward an infinitely expanding horizon.
1. Out of the Cradle 1 | OUT OF THE CRADLE Humans aren’t native to all of planet Earth. We’re descendants of a small group of primates who evolved for millions of years in the Great Rift Valley of East Africa. It’s our technology that enabled us to expand across the globe, starting around a hundred thousand years ago. There were earlier waves of proto-human migration, to be sure. Homo erectus was the first to leave the cradle, beginning its migration across Eurasia around 1.5 million years ago. Our cousins in that hominid line were the first to reach the Middle East, China, and Southeast Asia, and the first to command fire. Homo erectus also hunted large animals for the first time, and developed sophisticated tools. They may have built rafts, and even crossed large bodies of water, but it seems that once they left the cradle, they never returned. Theirs is not our story.
Next to leave Africa, before eight hundred thousand years ago, was a group appropriately named Homo antecessor. These wanderers may have been progenitors not only of us, but also of our closely related cousins the Neanderthals (there is some debate about the precise lineage). Homo antecessor looked essentially like us but was on the stocky side with a slightly smaller skull and brain. The smaller brain conferred several advantages: it consumed far less energy than our copious gray matter, and it permitted faster development and maturation. Whereas modern humans can’t reproduce until around age twelve, a typical Homo antecessor functioned as an adult by eight or nine.
Around six hundred thousand years ago, Homo antecessor gave rise to Homo heidelbergensis, probably the first species to develop a sophisticated culture with a fully vocalized language, a ritual of burying their dead (proto-religion?), and cave art (we’ve found the remains of dye but no paintings per se). With more advanced technology (tools, fire, animal-skin clothes), Homo heidelbergensis bands reached the cold climates of Europe and Siberia. When Homo heidelbergensis expanded through Eurasia, it would have encountered Homo erectus and its descendants, who were already living there. In fact, for most of history, there’ve been many species of humans on Earth. It’s actually quite astonishing that we live at a time when there’s only one type of human. This situation has only persisted for the last thirty thousand years or so—less than 1 percent of the time hominids have been around. Undoubtedly, there were many past interactions among different human species. What would those encounters have been like?
It’s possible that different human species mostly ignored each other, or they might have cooperated and traded. At the other extreme, they might have hunted each other. Groups of chimpanzees are known for raiding, killing, and even eating other primates, including other chimpanzees of the same type. And there’s some evidence for cannibalism among early hominids (as well as some modern humans, to be sure). Would different human species have regarded each other as “people” or as types of “animals”? Perhaps neither. Diverse animals often congregate around a water hole without showing hostility. Maybe early hominids regarded each other with little more than mild curiosity.
While these encounters between Homo heidelbergensis and Homo erectus were playing out across Eurasia, our immediate ancestors were still confined to a small area in East Africa. The next time someone asks you where you’re from, you can say, “Somewhere near Lake Turkana.” There weren’t many of us, and we almost didn’t make it. At times, our entire population dwindled to a few thousand individuals. One of the expansion bottlenecks may have been the eruption of the giant Toba supervolcano on the island of Sumatra about seventy-five thousand years ago, which spewed enough ash into the atmosphere to trigger a six-year volcanic winter. These bottlenecks are the reason that humans are among the least genetically diverse species on Earth. Despite the superficial variation in human appearance around the world, humans are exceedingly similar. We know this from gene studies that measure the divergence of mitochondrial DNA as human groups became separated over time.I
It’s unclear where we should draw the arbitrary line marking modern humans. The oldest fossil indistinguishable from a modern human is around 195,000 years old, uncovered in Kenya in 1975. But perhaps a better indicator is culture. Blombos Cave in South Africa, dating back 100,000 years, represents one of the earliest sites that shows a full range of modern human behavior. Evidence there suggests diverse resource use, multistep and multimaterial tool construction, complex art, social organization, and ritualistic behavior. Specific finds include the remains of shellfish, birds, turtles, ostrich eggs, ochre dye, engraved bones, detailed stone tools, and seashell beads used for decoration. (The “modernity” of the cave’s occupants lies in the variety of animals they ate and their sense of vanity.)
The migration of some members of our species out of Africa is sometimes called “Out of Africa II” to contrast it with previous hominid departures, but don’t picture hordes of people on the continent’s borders waiting for the starter’s whistle to blow. The dates are imprecise, the numbers of migrants very small, and the areas covered enormous. There’s also a good deal of disputed evidence. Most scientists think that there were actually two waves of Homo sapiens leaving Africa—the first wave leaving around 120,000 years ago but not getting much farther than the Middle East, the second decisive wave departing 50,000 years later. Either way, between 120,000 and 70,000 years ago small bands of modern humans left Africa, never to return. By 50,000 years ago at least some adventurers had reached Australia, either by means of a land bridge during a period of low sea level or by traveling on boats from Indonesia. By around 40,000 years ago, humans had spread into Europe and Siberia, some coming up from the Middle East, others crossing at Gibraltar into Spain. By around 14,000 years ago, humans had arrived in the Americas for the first time, by crossing from Siberia into Alaska.
Modern humans were the first people to reach Australia and the Americas, but everywhere else they would have encountered people from earlier waves of migration. In Europe and the Middle East our ancestors had significant and sustained contact with Neanderthals, who’d been living there for hundreds of thousands of years. Neanderthals weren’t so different from us. They were stronger, and possibly smarter. They crafted sophisticated tools and probably spoke a verbal language. They built simple boats and hunted large animals like mammoths. Stocky, barrel-chested, and powerful, they were at least a match for us on an individual basis. Neanderthals were so closely related to Homo sapiens that interactions between the two were probably no different than among two tribes.
Recent evidence suggests that Neanderthals were already in decline by the time our ancestors arrived, but it seems likely that there were at least some bloody conflicts as tribes of early Homo sapiens moved in to occupy the same territories. One of the more interesting notions put forth is that our ancestors carried diseases that Neanderthals hadn’t been previously exposed to, foreshadowing contact between the Old World and the Americas. However, the likely truth is that Neanderthals were simply outcompeted. Perhaps better technology enabled our ancestors to more efficiently hunt animals and gather food. This is especially plausible since Neanderthals’ larger bodies and brains would have required more nourishment, making them more susceptible to starvation.
Whatever the reason, between around forty thousand and twenty-eight thousand years ago, Neanderthals disappeared from the planet—but not entirely. The Neanderthal Genome Project has confirmed that significant portions of Neanderthal DNA still exist in modern humans. The exact amount varies by geographic location (less in Africa, where modern humans never left), but many populations seem to have up to 4 percent Neanderthal-sourced DNA.II This isn’t enough to represent a complete convergence of humans and Neanderthals, but there was clearly some mixing going on. If your ancestors are from outside of Africa, you may want to blame your Neanderthal heritage for your bad knees or inability to stick to your diet—though, of course, it won’t do you much good.
Following Homo sapiens’s exodus from Africa, our species spread out to occupy every corner of the planet, with the exception of Antarctica and a collection of islands far out at sea. Along the way, we perfected the command of fire, the use of animal skins for clothing and shelter, and the manufacture of stone and bone tools. We domesticated dogs to help us hunt and guard our camps, or perhaps they domesticated themselves by self-selecting for tameness.III We invented the elements of culture, with carvings, cave paintings, and objects for ritual burial. Around twenty-five thousand years ago we invented pottery, ropes, harpoons, saws, sewing needles, braided baby carriers, baskets, and fishing nets. Also around this time, the first permanent settlements appeared, such as the ancient rock-and-mammoth-bone village unearthed at Dolní Vestonice in the Czech Republic.
What really changed the way humans lived on a massive scale was agriculture. It all began when hunter-gatherers in the Middle East, China, and Mesoamerica began sticking around longer in places that supported naturally growing wild grasses—the ancestors of wheat, barley, oats, rice, corn, and every other grain we know today. It just made sense to select the best of these wild grains to preferentially plant for harvesting the next year. Thus, totally inadvertently, these early people set humanity on a course toward sedentary living. Was this a good or bad thing? On an individual level, some hunter-gatherers managed healthier and more varied diets, but only in times of plenty when they could find enough food. Many more people can be consistently supported on grain. Today over half the calories consumed by humans on Earth come from just three types of grass: corn, rice, and wheat. Agriculture has been the essential ingredient of civilization, allowing us to support large populations that can work together.
For 97 percent of our existence, humanity had lived in small nomadic bands of fewer than a hundred individuals, organized around extended families. Living together with strangers required the development of power structures and laws to govern the behavior of a species still prone to restless violence. Communal interaction accelerated technological innovation through specialized production, collaborative problem solving, and the ability to exchange ideas. We domesticated animals on a large scale and learned to forge metals. We developed economies, religions, and armies in financial, cultural, and military struggles with neighbors. Agriculture put an end to our nomadic wandering but established the conditions for massive technological expansion, which would give us the tools to once again expand outward in a second wave of exploration.
Andrew Rader is a Mission Manager at SpaceX. He holds a PhD in Aerospace Engineering from MIT specializing in long-duration spaceflight. In 2013, he won the Discovery Channel’s competitive television series Canada’s Greatest Know-It-All. He also co-hosts the weekly podcast Spellbound, which covers topics from science to economics to history and psychology. Beyond the Known is Rader’s first book for adults. You can find him at Andrew-Rader.com.
“In this book, he seems to capture every act of exploration carried out by the human species since we learned to walk upright. Andrew’s view of things is that long after everyone else in human history is forgotten, it will be the explorers who earn a measure of immortality.” —Rick H., VP, Executive Editor, on Beyond the Known
“Has an air of authority as well as a lively pace….Good scientific speculation that will leave readers yearning to see how it turns out. ‘If the history of exploration has taught us anything,’ Rader writes, ‘it's that amazing things happen when humans force themselves to try something no one has done before.’ An astute—and highly flattering—view of human aspirations.”
“A thrilling and irresistible history of human exploration, Andrew Rader’s Beyond the Known shows as much admiration for the Polynesians who conquered the Pacific in outrigger canoes as for the astronauts who will take us to distant planets. Celebrating discoverers from every continent, this is world history at its best.” —Eugene Rogan, Professor of Modern Middle Eastern History, University of Oxford, and author of the international bestsellers, The Arabs: A History and The Fall of the Ottomans: The Great War in the Middle East
“In Beyond the Known Andrew Rader achieves something almost as ambitious as the pioneers he writes about: he retraces the 10,000-year history of exploration, from the Stone Age to the Space Age, in a single book-sized expedition. As the centuries flew by, I learned something new on every page." —Ken Jennings, Jeopardy! champion and New York Times bestselling author of Maphead
"Scintillating, coruscating, Beyond the Known shows just how powerful the human urge to travel, to explore, to move always has been and always will be. It is a light on the past—and for the future." —Anthony Pagden, Distinguished Professor of Political Science and History at UCLA and author of The Burdens of Empire: 1539 to the Present
“Andrew Rader’s Beyond the Known is a smashing narrative about the history, the promise, and the innately human drive to explore, from antiquity to today to the coming Star Trek era. I could not put it down!" —Alan Stern, Principal Investigator of NASA’s New Horizons Mission, and author of Chasing New Horizons: Inside the Epic First Mission to Pluto
“Beyond the Known is an engaging, full-color route map showing us how we got here, and where we’re now destined to go.” —Tim Marshall, New York Times bestselling author of Prisoners of Geography and The Age of Walls