The Aliens Are Coming!
Page 18
“I always wanted to fly,” says Nicky Clayton, as she spins her Audi TT around in a Cambridge side street, evading yet another civic roadblock. “That’s why I love dance.” I nod enthusiastically. That explains why my bag is currently rolling around in the trunk next to an entire wardrobe of lacy costumes and what can only be described as killer heels. Seconds later we are heading toward her laboratory in Madingley, on the outskirts of Cambridge, and I briefly wonder whether the front of the car is going to achieve aerodynamic lift and grant her wish.
The building we arrive at has the understated hush of a local tennis club, with pavilion-style wooden huts surrounded by lawns and meshed enclosures. Instead of the thwock of brushed cotton on catgut, however, the air tinkles with birdsong. That’s because, by night, Clayton is a dancer, but by day she is Professor of Comparative Cognition in the Department of Psychology at the University of Cambridge. What’s more, she has made a considerable name for herself studying the intelligence of a previously overlooked species, the crow.12
Through a series of ingenious experiments, Clayton and her coworkers—her husband Nathan Emery is one of her collaborators—have demonstrated that, far from being “bird brains,” when it comes to intelligence, crows show a great deal of similarity to apes. Crows are foragers, for example, and love to hide food. In one famous experiment, Clayton and her team devised a sort of “crow motel,” where western scrub jays spent the night in one of two bedrooms. In one, breakfast was served in the morning; in the other, no such luck. After a stay of six nights, alternating between the two bedrooms, the jays were unexpectedly given nuts in the evening. Much as you or I might do, the crows hid food in the bedroom that came without breakfast, just in case.
That result is interesting, because it has been mirrored in similar experiments with apes. In one test, for example, chimpanzees and orangutans were shown how to use a plastic hose to suck fruit juice from a container. Later, in a separate room, they were given a choice of four objects, one of which was the hose. Knowing that they would later encounter the container, the apes cunningly selected the hose. Apes and crows, in other words, aren’t imprisoned in the here and now; they are capable of imagining their future and of planning for it.
Not only that, but Nicky’s team has also demonstrated that crows are capable of designing tools, as well as reasoning, problem-solving, empathizing, and even deliberately deceiving one another. Other experimenters have shown that all of these abilities are shared by apes, though in my opinion, when it comes to tool-making, it’s the crows that have the edge. And all this despite the fact that crows and apes have completely different kinds of brains, as you might expect with two species whose last common ancestor was an amniote13 that roamed the Carboniferous forests some 300 million years ago.
So what caused the intelligence of crows and apes to converge? Clayton makes some intriguing suggestions. Both animals are highly social, and, as we all know, to get ahead in society you need an ability to play politics. That requires brainpower, and it may be that group living is one of the drivers toward animal smarts. Second, both apes and crows are foragers, living off seasonal foods that are tricky to identify, hard to get at and distributed over a wide area. In this case, it’s not just the early bird that catches the worm, but the one that’s gifted enough to drop stones into a pitcher of water.14
And third—and to my mind, most significantly—both chimpanzees and crows first appeared between ten and five million years ago, a time of rapid climate variation as the Earth limbered up for the present Ice Age. Interestingly, that’s also when our own hominin line diverged from the common ancestor it shares with Pan, the genus to which chimpanzees and bonobos belong. One way to get around a changing climate, of course, is to use your intelligence to help you find food and shelter. Could what Clayton calls the “clever club” of apes, crows, parrots, dolphins, and elephants be a direct result of unpredictable weather?
For those of us seeking to contact aliens, the implications of all this are profound. Just as we can expect the inhabitants of Earthlike planets to fly, bite, and see by the light of their home star, we should also expect them to be smart. Because despite what we might want to believe, intelligence is not a uniquely human trait; we share it with crows, dolphins, elephants, and no doubt a whole zoo of other terrestrial species yet to be investigated.15 Its basic components—things like reasoning, problem-solving, imagination, memory, and mental time travel—crop up time and again.
WAR OF THE WORLDS
So we have half an answer to the question of what an intelligent alien might look like. First, it will have a complex brain. Whether that brain is centralized, as it is in birds, mammals, and dolphins, or decentralized as in octopuses, we can be less sure. It will have acute senses, whether attuned to light, sound, heat, chemicals, or electric fields. It will most likely eat a wide variety of foods, be extremely dexterous with physical objects, communicative, and social. Large portions of its long life will be spent learning from its society, parents, and peers. And it will quite possibly have evolved in an ever-changing terrain, where it used its intelligence to stay one step ahead of the game.
As to whether it has six legs, fur, feathers, or a two-inch-thick coating of mucus, all bets are off. Certainly, if it resembles any of the family groupings we recognize on Earth—vertebrates, or invertebrates, for example—that will be a fluke. There is nothing special about the order in which species have diverged here on Earth; if we re-ran evolution it might just as well be a ray-finned fish rather than a lobe-finned fish that gave rise to the first amphibians, for example, and we might have inherited six digits per hand rather than five.
If it comes to that, of course, if we re-ran Earth evolution we might not even get as far as the lobe-finned fishes. There are considerable hurdles to jump on the track to complex life as we know it, with one of the hardest to clear being the creation of the eukaryotic cell and its energy-giving mitochondria. Another is the evolution of oxygenic photosynthesis, whereby chlorophyll is used to harness light energy to rip electrons from water and stuff them on to carbon dioxide to make sugars. Fail to make it past either of those and all you get is an ocean full of bacteria, much as we had for the first two billion years of life on Earth.
As we shall see in a moment, there are reasonable arguments as to why the eukaryotic cell might be convergent, and how we might get by with ordinary photosynthesis rather than the souped-up, oxygenic kind, but however you slice it, the sixties Star Trek trope of landing on an opulently flowered Eden inhabited by nubile blondes and beaux with negligible body hair is very much an outside bet. Even though it ticks all the above boxes for brain size, dexterity, and communication, the intelligent alien on the other end of the phone might look more like a crab, or a spider, or an octopus; even more likely, it will resemble none of the above, but for a sucker here and an eye there.
Of course, it takes a lot more than just intelligence to make a communicable alien. Humans are smart, but not that smart. What really sets us apart is civilization; what made that possible was the invention of farming. As we entered the Holocene, and the snows retreated, everyone got their hoes out. Or to be precise, they got the halters out; the hoes came shortly after. Farming, too, appears to be highly convergent, emerging roughly 11,500 years ago in the stable climate of the Holocene in Southeast Asia, the Levant, the Fertile Crescent, South America, and Europe. Oh yes, and roughly fifty million years ago in the Attine ants of the Amazon rainforest.
ALIEN ANT INVASION
Not that they were farming rice and rye, of course; the preferred crop of the Attines is fungus. One particularly sophisticated group, the leafcutter ants, live in civilizations over five million strong, with precise divisions of labor. Their underground nests reach enormous size; one excavated in Brazil in 2012 was more than five hundred square feet across and more than twenty-five feet deep. A network of tunnels provides access and ventilation to large underground chambers where the fungus is fed with leaf mulch; the fungus breaks down the cellulose in the leaves so t
hat both it, the ants, and their larvae can digest it. As the fungus grows, the ants prune it, fertilize it, and even treat it with antibiotics when it becomes infected with other parasitic fungi.
I’m sure by now you are getting the picture: There is almost nothing about humans that is unique. There are plenty of other creatures out there that walk on two legs, give birth to live young, or farm for a living. Ants, of course, aren’t great shakes in the cognitive department, which is why they aren’t planning a flyby of Europa—not on this planet, anyway. On the one hand, that’s a little disappointing; we humans love to feel important, and it’s a bit disconcerting to discover that a six-legged creature in the Amazon jungle mastered the antibiotic before we did, but when it comes to our quest to find other communicable life in the galaxy it should give us great heart.
All the important stuff like intelligence, language, tool use, farming, and civilization is convergent; it has evolved before, in countless other species. And while no one was waiting for humans to be the ones that got their act together first, by chance that is exactly what happened. True, evolution has not been conducted with us in mind; when the first archaeon left the vent, it wasn’t with the express intention of one day wandering about Soho with a copy of Time Out. But the ratchet of natural selection has spent the last four billion years layering complexity upon complexity; it was just a matter of time before one species lucked out.16
THE INFORMATION SUPERHIGHWAY
And the precise way in which we lucked out, of course, was that we came up with a method for storing information outside our physical bodies. As previously mentioned, the first phonetic writing system is believed to have emerged in Sumer in Mesopotamia around 3100 BC. As Claude Shannon would have noted, this marks a profound change. Before writing, DNA was the only way nature had of making a “hard copy”; afterward, anything anyone had a mind to write down could be preserved for generations.
From Mesopotamia, the technology of writing spread quickly west to Ancient Egypt, and then around the Mediterranean, courtesy of the Phoenicians. The Ancient Greeks adopted the Phoenician alphabet, and bequeathed it to the Romans. We have no way of knowing whether there were cavemen as wise as Socrates, but thanks to writing, even 2,400 years later we are intimately acquainted with his every thought.
Information, let’s not forget, is a physical thing. While the Sumerians had scored their marks in wet clay, the Egyptians had something far handier—papyrus—from which they were able to make the first books and eventually to found the first library in roughly 300 BC in Alexandria. Writing not only meant that information could be preserved; it could also be copied. Reportedly, when a ship cast anchor in the port of Alexandria, any written works on board would be confiscated on behalf of the library and judiciously copied.
As seekers of alien civilizations, we would do well to note that besides the Mediterranean and Middle East, writing appears to have independently evolved in both South America and China, so we can be reasonably sure that it, too, is convergent. The Chinese, in fact, not only invented modern paper, but also the first woodblock printing. They were also the first to invent movable type,17 but for some reason—the vast number of characters in Chinese script, perhaps—the idea appears not to have caught on.
In AD 751, the western expansion of the Tang Dynasty was halted by the Abbasid Caliphate at the Battle of Talas, and the Chinese prisoners of war revealed the secrets of papermaking to their captors. By AD 794, paper was being manufactured in Baghdad. Throughout the Middle Ages, Islamic scholars built upon the classic Ancient Greek texts, laying the foundations of modern science and mathematics.18 Thanks to the Crusades, Muslim scholarship and papermaking technology eventually began to reach Western Europe, and by the late thirteenth century first Italy, and then France and Germany, became centers for papermaking.
Another leap then came with the invention of the printing press by Gutenberg in 1450; as information flooded across Europe, it suddenly switched from being a backward region to being the proud home of scientific greats such as Leibniz, Kepler, and Newton. Their discoveries in turn ignited the industrial revolution of the mid-nineteenth century with its mechanization of farming, manufacturing, and the production of energy. Finally, the present digital age has seen every bit of information in existence made available online, orbiting the planet in an impenetrable electromagnetic swarm.
As humans, we find it difficult to see our technology as part of nature, as much the product of natural selection as, say, the anthill or the shell of a snail. Our snaking motorways and dotted radio masts appear to us to be a very different thing from the veins of a leaf, or nodes of a spider’s web, but of course they are fundamentally the same. To see something like the internet as a natural extension of the human organism feels absurd, but it’s important to ask the question: What is all this information for?
Take the evolutionary biologist’s view, and the answer comes back with resounding clarity: It’s not “for” anything. Pieces of information that are good at getting themselves copied will eventually come to dominate the world, whether they are the gene for blue eyes or the code for a cute cat video. One fruitful strategy is to improve the fitness of their host. The information in your iPad improves the chances that you will have offspring, just as that in your DNA does. Admittedly, it’s a bit hard to see the direct effect that reading a good Dick Francis novel has on your capacity to bear children,19 but, believe me, that may well be why he’s there. Zoom out and look at the big picture and the facts are undeniable. Since the invention of writing, human population has grown with exponential fury.20
Throughout this book we have tried to figure out what intelligent life on Earth can tell us about intelligent life on other planets. The first vital step was the creation of the cell; the next was photosynthesis. The evolution of the eukaryote enabled the leap to multicellular life; that was followed by the evolution of animals, or metazoans. Finally, the shift from DNA to silicon as a means of storing information enabled the accomplishments of human civilization to transcend anything that might be possible for an individual human. Writing is convergent, and with writing comes an explosion of information that transforms a tribe into an accomplished technological civilization. If there are other Earths out there, there could well be aliens like us to talk to.
But what about planets that aren’t like the Earth? Might we find intelligent communicable life on them? And, if we do, what would those aliens look like? It’s time to cast our net a little wider, and fish our neighboring solar systems for life-as-we-know-it. And, finally, we shall need to cast our net a little wider still, and fish for the ultimate prize: life-as-we-don’t. Could there be intelligent beings out there whose chemistry is based on an element other than carbon? Does life even need chemistry at all? Could it take root in a dust cloud, or on the surface of a star? And how would we know it if it did?
SUPER-SIZE ME
If we’ve learned one thing in the course of our journey together, it’s that here on Earth the vital steps that led to the emergence of communicable life took a great deal of time, a total of roughly four billion years.21 The problem is that while the lifetime of Sun-like stars is something like ten billion years, after half that time they start to run out of hydrogen and heat up. Bit by bit, over the next 500 million years the Sun will vaporize the world’s oceans and turn our planet into a smog-choked desert. Put simply, the window of opportunity for stars like the Sun to develop creatures like ourselves is a little bit on the snug side.
Fine, you might think: Let’s find the longest-lived stars out there and look for Earth-sized planets in their habitable zones. But there’s a problem. The longest-lived stars are the smallest, dimmest ones, known as red dwarves. Red dwarves have lifetimes of up to trillions of years, but not only are they far less stable than the Sun, spitting out all sorts of nasty radiation, their habitable zones sit much closer in. That means any wet rocky planets they happen to have will be right in the firing line.22
Happily for us, however, there’s an a
lternative. There’s an intermediate size of star, the so-called orange dwarves,23 that are perfect for nurturing life. Not only do they have long lifetimes, in excess of fifteen billion years, but they are stable, like the Sun. In fact, they even emit much less harmful ultraviolet light than Sun-like stars; here on Earth we only managed to get decent protection from UV after the formation of the ozone layer, following the Great Oxidation Event roughly 2.3 billion years ago. Perfect. So we should look for Earth-sized planets in their habitable zones, right? Wrong.
Unfortunately, when it comes to long lifetimes, small rocky planets like the Earth won’t cut it. One of the most crucial ingredients for carbon-based life, as we know, is plate tectonics. Not only does outgassing from volcanoes keep the atmosphere full of carbon dioxide, and therefore keep geologically active planets from freezing over, but, according to our pet theory, it’s in volcanic vents on the sea floor that life gets its start. No volcanoes, no life. And to be volcanic, of course, the center of a planet needs to be hot. The problem is, small rocky planets like the Earth will cool down long before an orange dwarf burns out.
This is where super-Earths come in. Being several times more massive than the Earth, they keep their heat longer and can easily remain volcanically active for the long lifetime of an orange dwarf star. Along with a molten core, of course, comes a magnetic field, and protection from harmful cosmic rays and solar flares. Some, such as René Heller of the Institute of Astrophysics, Göttingen, even go so far as to call such planets “super-habitable,” better than Earth for the evolution of life. And the kicker is that, unlike diminutive Earth-sized planets, they will show up well in the next generation of telescopes.
INTELLIGENT LIFE 2.0
So what would life on a super-Earth in the habitable zone of an orange dwarf star look like? Just as in the case of an Earth-sized planet, while it is impossible to predict the precise route that evolution will take to get there we can make some informed guesses as to where it will end up. And thanks to the fact that it can run for nearly twice as long as it can here on Earth, that may be a very interesting place indeed.