by Caleb Scharf
Since the 1960s more than 530 humans have spent time in space, either lobbed into suborbital flight or zipping around in Earth orbit. On nine occasions we’ve gone on the long haul to and from the Moon, setting foot on it six times. As much as these experiences have showcased our technical prowess, they’ve also brought us a profoundly different view of our world than was afforded any of the billions of biologically modern humans that came before.
These lucky astronauts, cosmonauts, and taikonauts have found themselves in awe of what they’ve seen. Here is Earth in some of their words:
I think the one overwhelming emotion that we had was when we saw the Earth rising in the distance over the lunar landscape…. It makes us realize that we all do exist on one small globe. For from 230,000 miles away it really is a small planet.
—Frank Borman, Apollo 8, press reports, January 10, 1969
The Earth was small, light blue, and so touchingly alone, our home that must be defended like a holy relic. The Earth was absolutely round. I believe I never knew what the word “round” meant until I saw Earth from space.
—Aleksei Leonov, USSR
My first view—a panorama of brilliant deep blue ocean, shot with shades of green and gray and white—was of atolls and clouds. Close to the window I could see that this Pacific scene in motion was rimmed by the great curved limb of the Earth. It had a thin halo of blue held close, and beyond, black space. I held my breath, but something was missing—I felt strangely unfulfilled. Here was a tremendous visual spectacle, but viewed in silence. There was no grand musical accompaniment; no triumphant, inspired sonata or symphony. Each one of us must write the music of this sphere for ourselves.
—Charles Walker, USA
Earth’s varied hues, viewed from above Lake Turkana, in northern Kenya and Ethiopia
We learned a lot about the Moon, but what we really learned was about the Earth. The fact that just from the distance of the Moon you can put your thumb up and you can hide the Earth behind your thumb. Everything that you’ve ever known, your loved ones, your business, the problems of the Earth itself—all behind your thumb. And how insignificant we really all are, but then how fortunate we are to have this body and to be able to enjoy living here amongst the beauty of the Earth itself.
—Jim Lovell, Apollo 8 and 13 astronaut, interview for the 2007 movie In the Shadow of the Moon
A Chinese tale tells of some men sent to harm a young girl who, upon seeing her beauty, become her protectors rather than her violators. That’s how I felt seeing the Earth for the first time. I could not help but love and cherish her.
—Taylor Wang, China/USA
Above Kenya, the first small signs of human existence
As we come closer, the signs of complex life begin to pepper Earth’s landscape.
6
BEING CONSCIOUS IN THE COSMOS
103, 102, 10, 1, 10−1 meters
From 1 kilometer to 10 centimeters
From the length of an easy walk to the approximate size of your hand
So far, we’ve gone from scales where entire galaxies are like glinting motes of dust to scales where whole planets are mere droplets of solidified minerals. Now we’ve arrived at a scale where we are the motes scattered across the world. It’s taken about twenty-four orders of magnitude to get here.
From inside the membranes of our multicellular motes of mostly water, we spend our lives looking, listening, smelling, and feeling. Somehow we construct meaning out of those senses. We have that slippery property we call consciousness, and we also have that faculty we label intelligence.
It may be that other complex life across the cosmos is built the same way. We simply don’t know yet whether or not that is the case. Perhaps our biology is not the only way to construct living things. We also don’t know if human intelligence is a good example of how intelligence works everywhere—or, for that matter, what we really mean by intelligence. It could simply be the ability to solve mazes or open cans of food. Or it might be better gauged by the capacity to perform mathematical proofs and figure out the nature and origins of the universe.
Consciousness makes these conundrums even trickier. For thousands of years philosophers, scientists, poets, and artists have driven themselves crazy trying to figure out what consciousness is. Many modern neuroscientists would say that consciousness is our brain’s way of integrating information, of assembling a coherent model of the world as fed through our senses. But that also means that consciousness is more than the sum of its parts. Consciousness may be a new and irreducible state built from the electrochemical gunk in our brains.
Gazing out from a watering hole on Earth hundreds of thousands of years ago at the cosmic watering holes of the universe
Altogether our situation is a bit farcical. We’re in a horrendously unsuitable place for gaining objective truths about the nature of reality: inside a singular, self-aware mote of flesh drifting through space and time. And yet, it is precisely that aspect of our nature that compels us to ask all these awkward questions. It’s easy to argue that this very act of self-examination needs to be examined.
That’s nasty. It’s like trying to write a piece of computer code that interprets and debugs itself, or asking an artist to paint a picture of what it’s like to paint a picture. That’s also a challenge in our journey through all physical scales of existence. All we can really do is home in on one small rocky planet that orbits one ordinary star out of a trillion trillion stars in the observable universe and cross our fingers that this helps us disentangle the phenomenon of life.
To cap it all, life’s basic forms can be deceptive. Very little is as it first appears to our eyes. For example, an octopus is not just an octopus; it is tightly linked to other organisms and embedded in a web of biological evolution across epic timescales. Even its body is a landscape where trillions of smaller entities play out their Darwinian battles.
At an even more fundamental level, all life as we know it appears to be the emergent product of the interaction of mind-numbingly large numbers of tiny, repeated, varied, and recombined structures. As we’ll see, these molecular building blocks are the direct result of the physics of protons, neutrons, electrons, and electromagnetic forces.
Such tiny components simply follow the fundamental “rules” of the universe that were locked into place some 13.8 billion years ago. Yet, in concert, they can build galaxies, stars, planets, elephants, humans, birds, bugs, and who-knows-what-else across the cosmos.
How does this happen? That question sits at the absolute core of scientific and philosophical inquiry, at the heart of our efforts to construct a rational picture of nature from our inconvenient vantage point. The answer is a work in progress.
LIFE ON THE CRUST
Part of our progress on these tough questions about existence comes from better quantifying our home in the universe. That process starts simply enough. For example, 70 percent of Earth’s crusty exterior is covered in liquid water. That zone represents a great, and greatly varied, habitat. It is filled with life on all scales, from microscopic single cells to some of the largest individual multicellular organisms that currently exist on this world.
The hugely diverse dry land masses represent another set of habitats altogether, almost a parallel dimension to the oceans. Here life has had an opportunity to play out differently, even though the same underlying set of rules applies. These landscapes range from jungles to deserts, massive glacial ice caps to tropical islands, and mountains to plains.
For humans, one of the most intriguing spots when it comes to disentangling our journey from our origins lies in the Great African Rift Valley. This area is part of an extraordinary geographic trench. It’s a place where plates of planetary crust are literally pulling apart, fracturing a band of brittle minerals into a diverse patina.
Two sentient species inspect each other: humans in jeeps, elephants in their herd.
In eastern Africa, from Eritrea to Mozambique, this massive tectonic system—more than 6,000 kilo
meters in length—has caused an array of oversize geographic features, including stratovolcanoes, notably Mount Kilimanjaro, which rises almost 5,900 meters above sea level; dropped valleys with sides as high as 600 meters; and deep, fjord-like bodies of water. Lake Victoria, the world’s largest tropical lake, with nearly 70,000 square kilometers of tropical freshwater, helps feed the present-day Nile.
Within the Rift Valley we’ve discovered tangible clues to our own beginnings: the fossil remains of early species of humans, which have helped us write and rewrite our prehistory.
One of these species, known as Homo habilis, likely existed between 2.8 million and 1.5 million years ago. Another is Homo erectus, first appearing about 1.9 million years ago. Other proto-human fossils have been assigned distinct labels too, but the truth is that we don’t yet have a complete picture of who was loping around millions of years ago, and how they were all related. We also don’t really know how widespread these hominid species were, but it’s likely that their extent was regional rather than continental.
LOOK WHO’S WATCHING
Despite the long occupancy by strains of upright hominids, today there are still large areas of the Rift Valley where the flora and fauna are relatively unscathed by modern human standards.
In Kenya, for example, our journey through the scales of nature can bring us in just a couple of zooms from the hard vacuum of space to hover above a herd of elephants. They’re inspecting, and being inspected by, a small herd of nervous humans in their metal jeeps.
A few more twists of the telephoto lens bring us in on an individual pachyderm. And on an oxpecker bird sitting on that elephant and prying loose a juicy louse from folds of tough skin.
Taken in a larger context, this tableau is particularly intriguing. Here is a giant mammal, a 4,000- to 7,000-kilogram mass of multicellular life. It incubates its offspring in an internal womb and has glands that dispense nutritious milk to them for at least five years after birth. An elephant’s brain is a massive net of some 300 billion neurons (more than three times as many as a human’s). These creatures show complicated, and apparently altruistic, social behavior. They are almost certainly conscious. They are clearly intelligent, even if their smarts are not exactly like ours.
At the same time, the elephant’s feathery symbiotic companion has a different lineage, one that had a last common ancestor with mammals 300 million years ago. The oxpecker, like all modern birds, is a descendant of a particular group of “great lizards”—the egg-laying dinosaurs. Between 65 million and 260 million years ago, the oxpecker’s raptor ancestors scooted about this very same continental landscape. It was a world where dinosaurs had the evolutionary upper hand, or at least hogged the evolutionary limelight.
The oxpecker is certainly aware and intelligent by standards that we recognize. Many birds show signs of self-awareness, numeracy, and tool use. Yet a bird’s brain is physically much smaller than that of either the elephant or a human, and contains (only) about 100 million neurons.
Role reversal: Once, some dinosaurs succeeded as apex species, while mammals did not.
The parasitic louse in the bird’s beak has an ancestry that goes even further into the past. It is part of the group of wingless insects, at least 480 million years old, that evolved from a group of invertebrates. In that sense the louse is the most alien organism in the picture, and also the most successful, despite its present predicament.
Is the louse conscious or intelligent? Some insects, like bees, show behaviors that can be construed as signs of cognition, of intelligence, and can have upwards of a million neural cells. The louse is no bee, but we don’t know what’s really going on in its nervous system.
This one brief slice of life (a snapshot out of hundreds of millions of years of photo opportunities) contains another critical story.
A mammal hosts a bird and an insect. The bird consumes the parasitic insect, helping the mammal. The bird also feeds itself, and inadvertently contributes to variations in the genetic future of lice, since the unlucky louse’s lousy descendants will no longer exist. If this bird hadn’t sat on this elephant, and found this louse, a complex chain of future events would have turned out differently. In some futures this single event won’t matter. But in others it could, in principle, snowball to alter the entire evolutionary trajectory of life on Earth.
Chaos-inducing contingencies in history like these are only the tip of the iceberg. Elephants constantly alter the larger environment around themselves. They eat vegetation, they drink water, they move and disturb soil and rocks. In effect they promote external entropy, the quantifiable disorder of the universe. Plants and other organisms in this same environment feel the pressure of these changes, and natural selection (survival of the fittest), along with genetic drift (survival of the luckiest), causes biological change across all timescales.
The oxpecker does the same thing. It nests; it drops waste; it competes with other birds, with other organisms. And the louse, equal parts lowly and mighty, plays its role too. It is part of the community of lice, and it is an excellent home to the bacteria and viruses it carries through the ecosystem.
As we zoom into this seemingly innocuous snapshot of life in the Rift Valley, we’re catching a glimpse of what makes a true planetary biosphere—a staggeringly complicated, layered, and interlaced hierarchy of atoms, molecules, life, planets, stars, and cosmic thermodynamics.
Those curious phenomena we call consciousness and intelligence are slid into the interstices of this system. We don’t know whether complex life always has to evolve such characteristics to better survive, or whether these are oddities confined to life on Earth. We don’t know precisely how consciousness and intelligence scale from lice to elephants and beyond. But the actions of us humans can propagate far, far into the future, and far into the universe. Intelligence allows us to decide on those actions. The real question is how we choose to deal with such a capacity.
7
FROM MANY TO ONE
10−2, 10−3, 10−4, 10−5 meters
From 1 centimeter to 10 micrometers
From the size of a human fingertip to the size of a cloud-water droplet or an animal cell
The planet we call home is fading into the background as we zoom ever further down the cosmic scale. All of Earth’s color and drama is now just a blur that’s a billion times larger than the scope of our new waypoint. But this scale and the next few orders of magnitude within it are far from boring. You’re going to be challenged here by concepts that are both beautiful and strange. The first of these is what we call complexity.
Complexity is a central part of the currency of the universe. We’ve already encountered it out among the galaxies and nebulas, but it infuses our daily existence too. The very structure of our bodies and the multilayered populations of species that we live with are proof of that. Although we seldom notice, we live in a world of complicated biological granularity.
The built-in limitations of our senses don’t let us quite see this world for what it really is. If we hold two tiny objects at a comfortable distance from our faces, our eyes can only distinguish, or resolve, the pair if they’re separated by at least the width of a human hair. Cut that separation in half, and even the most eagle-eyed of us can’t tell whether we’re looking at one or two objects.
Because of this limitation, we’ve spent most of the past hundred thousand years painfully unaware of the universe beneath our noses, under our fingernails, in our blood, drool, and skin. We’ve mostly thought about our physical selves, and other creatures, as tightly wrapped packages. Everything from great beasts to lowly bugs appears equally solid and self-contained.
But all of us, like the rest of the cosmos, are composed of pieces. We consist of atoms, molecules, molecular complexes, and cells. And trillions upon trillions upon trillions of different mechanical and chemical interactions are possible among these parts.
Take the human hand, for example. Yours, busy holding this book in front of you, is poised in a state of dynami
c tension. Substantial bones, tendons, muscles, nerve fibers, and skin are all acting in concert. Together they sense and coordinate so that you can gaze steadily at these letters.
Many such hands of different colors, textures, and sizes have helped us imprint ourselves on the surrounding world.
We’ve taken our mental conceptions and carved them into shapes and figures from solid rock and iron. We’ve converted our thoughts into actual physical things that have in turn inspired ideas that have led to our hands making new things, and so on. Clever human fingers have let us fly in the sky, go to the Moon, and barrel into the outer reaches of our solar system. They’ve built machines to build other machines, from robots to self-assembling computers. They’ve also constructed microscopes out of carefully formed lenses and sensors, as well as enormous electromagnetic particle accelerators designed to dig deeper and peer at the subatomic realm.
Human hands and cells have let us engage with the universe.
The eye of a louse
Yet your hand is not really a single entity at all. This appendage consists of about 400 billion cells—highly specialized, membrane-wrapped capsules averaging about 0.03 millimeters across. It’s the concerted action of these tiny machines that lets you hold this book, just as other tiny machines are letting me type these words. And on a grander timescale, it’s the group action of these machines that helps drive human evolution.
The same is true for the rest of our bodies. It is also true of all large life-forms on Earth. By zooming into the Rift Valley in Africa, to an elephant, to a bird, to an insect, and on into that insect’s cellular structure, we can glimpse this granularity of life. It is remarkable what all those teeny tiny pieces do when they get together.