The Aliens Are Coming!

by Ben Miller

  We now find ourselves at the boundary of our present era, the Cenozoic. As already mentioned, the Mesozoic ended with a bang some sixty-six million years ago, when a giant space rock some six miles in diameter slammed into the Yucatán Peninsula in Mexico, releasing a billion times the energy of the atomic bomb that fell on Nagasaki. When random catastrophes like that occur, it tends to be the large predators at the top of the food chain that suffer. In this case that was the dinosaurs, of which only the birds survived.31 As we all know, our ancestors the placental mammals were all too happy to step into the breach.

  THE AGE OF MAMMALS

  Evolution, as you can see, often proceeds by fits and starts. The first step of the cycle is a radiation, where all sorts of genetic experimentation goes on as organisms adapt to new niches. The next is the dominance of a few particular forms: the land plants, say, in the Silurian and Devonian.32 Next comes an extinction, where the vast majority of species are wiped out on an utterly random basis. For the Gorgonopsids, that reckoning was the Permian extinction. The cycle is then free to begin again. And, true to form, a radiation of reptiles in the Triassic saw the rise of the dinosaurs in the Jurassic and Cretaceous.

  After the greenhouse world of the dinosaurs, the Cenozoic has generally seen a slow decline in global temperature, leading to the present Ice Age, the Quaternary, which began 2.6 million years ago. I know what you’re thinking; if this is an Ice Age, you hadn’t noticed, but an important feature of the Quaternary has been a gradual back and forth of polar ice. Epochs where the ice advances, known as glaciations, are interspersed with ones called interglacials where the ice retreats. As you might have guessed, we are in an interglacial right now, called the Holocene, where temperatures have been remarkably stable at roughly present-day levels for some 11,000 years.

  But back to my point. It’s thought that, as the polar ice formed, the planet became drier, and the African forests began to dwindle, giving way to savannahs.33 Forests, as we all know, are the natural habitat of apes. Could that have been the selection pressure that encouraged our ancestors to leave the trees? Whatever the reason, some seven million years ago they began to diverge from the ancestors of chimps. Interestingly, the adaptation that helped them wasn’t one that made them smarter. That came much later. They diverged because they could walk on two feet.

  What good did that do them? Well, not much, so far as we can make out, for several million years. The fossil evidence tells us that for the following four million years they gradually got better at walking upright, but that was about it. We find Ardepithecus shuffling across the forest floor some five million years ago, and Australopithecus sauntering upright on the savannah about a million years later, but they weren’t the smartest customers, with individual brain capacities roundabout the same as that of their cousins the chimps.

  Clearly they were doing something right, because just under two million years ago we find a radiation of hominins, or “human-like” species, all living cheek-by-jowl in Africa.34 Top billing goes to Homo erectus, with a brain capacity twice that of a chimpanzee, increased body size, and smaller teeth. Not only was this species the first true hunter-gatherer, it was also the first tourist, with some members leaving Africa to take up residence in Asia. The “smaller teeth” bit is particularly interesting, because it may hint at another link between energy and complexity. In short, there are some indications that Homo erectus could cook.

  Although we have yet to find solid evidence that it could control fire, the fact that Homo erectus has small teeth, small guts, and slept on the ground rather than in the trees are all intriguing clues. After all, cooking breaks down the long-chain carbon molecules in food, making it easier to chew and digest, dispensing with the need for a robust gut and dentition. It also means you can extract more energy from that vital adaptation, the gut. You can then expend that energy making your brain more complex, which in turn makes you a better hunter, creating a virtuous cycle.

  There’s another thing about cooking, of course. It’s also a group activity, set around a campfire, which must have encouraged all sorts of group bonding. As we shall see in the next chapter, intelligence is by no means confined to humans, but all the animals in which it occurs are social. It also encourages parenthood. Baby chimps are pretty much on their own once weaned, but cooking is technical, and not the kind of thing you’d ask a baby to do unless you were really in a rush. Cooking therefore encourages the dependency of children on their parents, buying time for childhood, a time of imaginative and creative development.

  PULLING MUSSELS FROM A SHELL

  To be fair, there’s currently a great deal of disagreement about what Homo erectus could or couldn’t do, and conclusive proof of tall stories by the campfire is a long way off. The conventional view is that they changed little in nearly two million years, using the same basic stone tools right up until their extinction some 140,000 years ago. In a book about communicating with aliens, however, I can’t help but mention a recent and very controversial discovery.

  This is also worth a Google. In scientific terms it’s a scratch on a mussel shell, but it would take a bard to do it justice. Recently dated at 500,000 years old, it comes from a treasure trove of Homo erectus fossils found on the Indonesian island of Java by a Dutch surgeon named Eugene Dubois in 1891. Something—or someone—has carved a zigzag pattern on it, and, when you see it, it’s hard not to feel a deeply human connection. I defy anyone to look at those markings, made by an ape nearly half a million years ago, and not to imagine that either it knew what beauty is, or sought order in a confusing world, or at the very least was bored and looking for something to do.

  The next time in the fossil record we find anything like these patterns, they are scratched in ochre by anatomically modern Homo sapiens.35 The site they come from, the Blombos Cave on the southern Cape coast, has been one of the richest sources of early human artifacts ever discovered. Dated at 100,000 years old, these criss-cross etchings speak to the existence of beings just like ourselves, capable of imagination, creativity, and abstract thought. Something crucial is happening here. Information is no longer simply being stored in DNA. It is being stored in a network of brains. The name of that network, of course, is culture.

  GONE WALKABOUT

  After a genesis in Africa some 200,000 years ago, Homo sapiens rapidly spread across the Levant, heading for Asia and Europe. With a seemingly solitary leap, its brain size had increased by over a third in comparison to Homo erectus, and was now over three times the size of that of a chimpanzee. If art is a proxy for language, as many paleoanthropologists believe, the indication from the Blombos Cave is that even these very first Homo sapiens were singing “I don’t know but I’ve been told” as they walked.

  Or maybe they just chatted about the weather. Either way, 45,000 years ago they reached Europe, where they encountered the Neanderthals, a separate hominin line that had already been living there for some 150,000 years. A talented bunch with their own toolmaking and burial traditions, as already mentioned the Neanderthals had bigger brains than us and were arguably better adapted to the cold climate. Whatever happened, it doesn’t seem to have involved much cooperation, because within 5,000 years the Neanderthals were extinct. Never let it be said that humanity doesn’t have a dark side.

  It’s around this time that we detect what is often called the “Great Leap Forward”: a step change in human culture. There’s evidence of elaborate burial rituals, of wearing animal skins as clothing, and using pit-traps to hunt prey. By the time we reach 40,000 years ago, you can hardly move in Europe or Asia without stumbling across all manner of cave paintings, jewelery, fishing hooks, and flutes.

  The invention of farming, roughly 11,500 years ago at the end of the last glacial maximum, secured a growing network of villages with a reliable energy supply. A few millennia later, around 3600 BC (5,600 years ago), came the founding of Sumer, the world’s first civilization, and, by 3100 BC, Sumerian had become its first written language. Now information could be
stored not just in the brain, or in a network of brains, but as hard copy. And progress continues to be relentless. Today, a dwindling supply of energy from fossil fuels supports a worldwide population of seven billion souls, connected by a digital network that contains just about every single bit of information amassed by humanity to date.

  THE UNBEARABLE LIGHTNESS OF BEING

  So that’s why we’ve never heard from aliens, right? The whole of human evolution hinges on one key event, the creation of the eukaryotic cell, without which the Earth would still, even four billion years later, be nothing but a petri dish for bacteria and archaea. There’s nothing out there for us to talk to, because, although single-celled life is common, complex life is rare, and intelligent life rarer still. The series of flukes that led to intelligence in humans hardly makes communicable civilizations look like a dead cert.

  So what are the chances that I should be here? Let’s assume for a moment that the time in Earth’s history when a given organism evolves is a good guide to its probability. This is a bit like rolling a die once a minute. After six minutes, all things being equal, you’d expect to have rolled at least one six. Since the Earth has been rolling the die for roughly four million years, and assuming the rate of mutation is roughly constant, we can calculate the probability of the various stages of life. Single-celled life has been there from the first roll of the die, so its probability is 1. Eukaryotic cells emerged halfway through Earth’s history, so their probability is ½, or 1 in 2. And we humans evolved 200,000 years before the present, so our probability is 200,000/4,000,000,000, or 1 in 20,000.

  Of course that calculation is riddled with so many assumptions it’s little more than a curiosity. The biggest is that the Earth is somehow typical of all life-bearing planets. To really get a feel for the probability of complex life, we need detailed knowledge of a large sample of life-bearing planets, something we are unlikely to have for at least a decade or two. Another is that only complex organisms with our own particular genetic make-up—that’s to say bipedal hominins—possess the kind of intelligence necessary to evolve technology and communicate. But it doesn’t look encouraging, does it? It suggests that simple life is common, but intelligent life is rare. From time to time a light comes on, but everywhere else is in darkness. Our project is in vain.

  Well, not quite. Because, as we are about to see in the next chapter, it turns out that we humans are not quite as unique as we might think. There are other intelligent species on the planet, and an argument can be made that intelligence is just as common an adaptation as land-dwelling or flight. As we are about to see, there’s a good chance that if we rewound the tape and played evolution out again, we’d find ourselves on a planet of the apes, dolphins, or crows.

  Not only that, but by focusing so sharply on the fine detail of evolution here on Earth, we’ve neglected the bigger picture. Yes, we are here because of a series of biological and climatic flukes. But we are also here because we had the time to evolve. We happen to live on a stable planet in a stable solar system, orbiting a quiet, long-lived star. When we look out into the galaxy, hoping to see our neighbors waving back at us, we are assuming that planets and solar systems like ours have existed since the Milky Way was founded, some thirteen billion years ago. But what if that’s just not the case? What if life started on Earth at the same time that life could start anywhere in the galaxy? What if we are one of a whole host of civilizations that are just waking up? In order to climb evolution’s ladder to complexity, we need to avoid its biggest snake: gamma ray bursts.

  HERE BE DRAGONS

  In 1963, following the Nuclear Test Ban Treaty, the US launched the Vela satellite, essentially to make sure that what was then the USSR was playing ball. These high-flying satellites were tuned to detect the distinctive pulses of visible light, radio waves, x-rays, and gamma rays emitted by nuclear weapons tests. Instead, they found something else: bursts of pure gamma rays coming from outside the solar system.

  To begin with it was assumed that these bursts must be coming from somewhere within the Milky Way, but by the mid-1990s it was realized that they are in fact coming from distant galaxies, many of which are almost halfway across the observable universe. To be as bright as they appear in our sky, having traveled billions of light-years to reach us, means that they must be extraordinarily intense. One particularly sobering fact is that a typical gamma ray burst (GRB) contains as much energy as the Sun radiates in its entire lifetime, condensed into a pulse lasting just a few seconds.

  We still aren’t exactly sure what causes these blistering infernos. The shorter bursts are thought to be caused by the collision of binary neutron stars. The longer, more powerful bursts are thought to result from the gravitational collapse of colossal stars, known as hypernovae. One thing is certain, however. You don’t want to be anywhere within 10,000 light-years of one, or you’ll be fried. The near side of any Earthlike planet would be toast, and the far side would then get blasted by a shower of secondary radiation. The ozone layer would be obliterated, and any remaining life would then be decimated by the Sun’s ultraviolet radiation.

  We now have a lot of data on GRBs, and in 2014 two astronomers named Tsvi Piran, of the Hebrew University of Jerusalem, and Raul Jiménez, of the University of Barcelona, crunched the numbers to find out what the risks are. Their findings make extremely interesting reading. For a start, they calculate that there’s a 90 percent chance that the Earth has been fried by at least one GRB at some time during the last 4.6 billion years, and a 50 percent chance that it has been hit within the last half-billion. Could one of the Big Five mass extinctions have been due to a GRB?36

  But it’s their conclusions about the suitability of the universe to past life that really give you pause for thought. For a start, only 10 percent of all galaxies have few enough GRBs to support life, and, even then, you’d better be nowhere near the center, where they tend to blow up more frequently. The Earth’s position, some 25,000 light-years from the center of the Milky Way—which is, as you might have guessed, a member of that lucky 10 percent—is now looking like prime real estate. But, most importantly, they calculate that life would have been impossible on any planet, in any kind of galaxy, anywhere in the universe before five billion years ago.

  What does that mean? The bottom line: We can trace two imaginary spheres around the Earth. The first is five billion light-years in radius, and within it we can expect to find single-celled life. Beyond that sphere the universe is barren, because any galaxy older than that is still being fried by GRBs. The second sphere is a billion light-years in radius. If life on Earth is typical—and that’s a fairly big “if”—then within it we can expect to find technologically advanced societies. After all, it took four billion years for humankind to develop radio technology, and if that represents some kind of average, then the very oldest communicable societies will be a billion years ahead of us at most.

  And finally, it raises a question. What if the Earth isn’t typical, and the rise of our own technological society has been inordinately rapid? What if, on average, it takes six billion years to invent radio technology, rather than our own four billion? In that case, we have a chilling solution to the Fermi paradox: We are alone. And if it takes, say, an average of five billion years to evolve a communicable society? Well, then, it’s all to play for. Maybe the galaxy isn’t dead. It’s asleep. And round about now it’s going to start waking up.

  CHAPTER SEVEN

  ALIENS

  In which the author conjures real aliens, and learns that life is a servant of two masters. One, consciousness, hopes that the universe lasts forever. The second, cosmos, seeks an untimely end. No prizes for guessing which one is winning.

  At first he assumed it had to be some kind of hoax. As Assistant Keeper of the Department of Natural History of the Modern Curiosities of the British Museum, George Shaw was often confronted with biological oddities, and a depressing number proved to be illegitimate. Accompanying the pelt was a sketch by its donor, Captain John Hunte
r, governor of the newly founded colony in New South Wales, purporting to show the animal when alive. Could the drawing be a fake, too? Even by Antipodean standards, the creature that confronted him was bafflingly bizarre.

  Where to start? Its tail was flat, like a beaver’s; its body was like that of an otter, or maybe a mole. Or, come to think of it, a seal; yes, he thought, that fur resembled nothing so much as a seal pelt. Like a seal, each of its four legs was home to a webbed foot. Yet search as he might, he could find nothing on the creature’s abdomen that in any way resembled a nipple. As proclaimed by the Swedish zoologist Carl Linnaeus in his definitive Systema Naturae, the class of Mammalia was reserved for “animals that suckle their young by means of lactiferous teats”. But if it wasn’t a mammal, what was it? Could it possibly belong within the class of Amphibia, many of whose members “appear to live promiscuously on land or in water”? Yet who had ever heard of an amphibian with fur?

  And then there was the business of the creature’s rear ankles. On each was a pronounced spur, much as you might see on a champion cockerel at a country fair. And that was the least striking of the creature’s avian characteristics.