Origin Story: A Big History of Everything

by David Christian

And, as Lemaître pointed out, if the universe was currently expanding, at some time in the

past, everything in it must have been compressed into a tiny space, something he described as the primordial atom.

While the big bang was pushing space apart, gravity was hustling around trying to pull energy and matter together.

Each star poured energy into the cold spaces around it, generating flows of heat, light, and chemical energy that could be used to build new forms of complexity in nearby regions. Those are the flows of free energy that allow life to flourish here on planet Earth.

Even today, about 98 percent of the mass of interstellar dust clouds consists of hydrogen and helium.

matter. Driving all this activity is the simple fact that electrons have negative charges that repel each other but attract them to the positive charges of protons, either in their home atom or in neighboring atoms.

Carbon, with six protons in its nucleus, is the Don Juan of these atomic romances. It normally has four electrons in its outer orbit, but there is room enough there for eight, so you can make a carbon atom happy by removing four electrons from its outer shell, by adding four electrons, or by letting it share four electrons with another atom. This gives it a lot of options, and that is why carbon can form complicated molecules with rings, chains, and other exotic shapes. Its virtuosity explains why carbon is so important to the chemistry of life. The basic

Indeed, we now know that simple organic molecules are common in the universe, and that increases the likelihood that life exists beyond planet Earth.

But living things are different. They don’t accept entropy’s rules passively;

instead, like stubborn children, they push back and try to negotiate.

Information begins with the laws of physics, the basic operating system of our universe.

And today, even in the chemically rich regions within galaxies, hydrogen and helium still make up 98 percent of all atomic matter.

In such a chemically rich environment, many of the simple molecules from which life is built can form more or less spontaneously. We are talking about small molecules, with less than a hundred atoms, including the amino acids from which all proteins are made, the nucleotides from which all genetic material is made, the carbohydrates or sugars that are often used like batteries to store energy, and the fatty phospholipids from which cellular membranes are built. Today, such molecules don’t arise spontaneously because atmospheric oxygen would rip them apart. But there was hardly any free oxygen in the atmosphere of the early Earth, so these simple molecules could form when given a few jolts of activation energy.

But most molecules inside cells, such as proteins or nucleic acids, are much more complex than these simple molecules. They consist of polymers, long, delicate chains of molecules, and forming polymers is not so easy. You need just the right amount of activation energy, and environments that can nudge molecules together in just the right way. One environment on the early Earth that might have provided the right conditions for stringing polymers together can be found at suboceanic vents, where hot material from Earth’s innards oozes through the ocean floor.

Life appeared early in the history of planet Earth, and that suggests that creating simple forms of life may not be too hard where the right Goldilocks conditions exist.

They are little more than packets of genetic material that glom on to more complex organisms. They enter another cell, hijack the cell’s metabolic mechanisms, and use it to make copies of themselves.

The proteins Luca made suggest that it lived at the edge of alkaline oceanic vents, probably inside tiny pores in lavalike rocks, and it got its energy from nearby gradients of heat, acidity, and flows of protons and electrons.

alkaline, which meant they had an excess of electrons.

Just outside the volcanic pores Luca called home were cooler ocean waters that were more acidic, which meant they had an excess of protons.

Suess saw Earth as a series of overlapping and sometimes interpenetrating spheres that included the atmosphere (the sphere of air), the hydrosphere (the sphere of water), and the

lithosphere (the rigid, upper levels of the Earth, including the crust and the top layers of the mantle).

Once joined in the supercontinent of Pangaea, or Pan-Gaia (a Greek word meaning “all Earth”), they had gradually diverged and moved to their present positions.

the two plates have about the same density—if, say, they both consist of granitic continental plates—then, like two bull walruses competing for mates, they will rear up. This is how the Himalayas formed;

oxygen is an electron thief and will combine eagerly with any element that has spare electrons.

That is why atoms that have had their electrons stolen are said to have been oxidized.

The exceptional chemical energy of free oxygen powered new chemical reactions that created many of the minerals on today’s Earth.

Protected by the ozone layer, some algae may have started colonizing the land for the first time. Until then, bathed in solar radiation that would have ripped apart any bacteria brave enough to venture onto land, the continents of planet Earth had been more or less sterile.

The appearance of a third domain of life-forms, Eukarya, matters a lot to us because all large organisms, including ourselves, are built from eukaryotic cells. These were the first cells that could use oxygen systematically, exploiting its fierce chemical energy in a process known as respiration, which is what we do when we breathe. Respiration is the reverse of photosynthesis and is really a way of releasing solar energy that has been captured and stored within cells through photosynthesis.

Animals may be evolution’s icing, but bacteria are the cake. —A

Our unusually large moon helped stabilize Earth’s orbit and tilt.

And, as we have seen, plate tectonics, erosion, and then life itself provided thermostats that stopped temperatures from wobbling too much at the Earth’s surface.

Indeed, many bacteria show herdlike behavior, which implies some sort of rudimentary communication system.

Genuine multicellularity is really an extreme form of symbiosis. But collaboration is made easier by the fact that most cells in metazoans are genetically identical.

case you are tempted

to see this as a sign of evolutionary failure, it is worth remembering that we humans have been around for just two hundred thousand years.

They were particularly rough on specialized species because extreme specialists, like modern koalas, had little room to maneuver in periods of rapid change. Mass extinctions were also hard on the largest organisms, which need more food and reproduce too slowly to keep up with rapid changes.

That’s why forests from the Carboniferous period (from 360 to 300 million years ago) were mostly buried beneath the soil, along with the carbon they had drawn down from the atmosphere. Over time, they fossilized to form the coal seams that later powered the industrial revolution. About 90 percent of today’s coal deposits were buried during the period of high oxygen levels, from around 330 to 260 million years ago.

Soot blocked sunlight, creating what we might describe today as a nuclear winter. Nitric acid rained from the sky, killing most of the organisms it touched. The surface of Earth would have been in total darkness for a year or two, shutting down photosynthesis, life’s lifeline to the sun.

After the planet returned to something like normalcy, survivors of the Chicxulub asteroid found themselves in a strange new world. With the dinosaurs gone, there were new opportunities. Mammals diversified in a new evolutionary radiation, as small businesses would today if every large

corporation declared bankruptcy overnight.

The best bet at present is that polar oceans warmed to the point where methane clathrates (frozen balls of methane, which look like ice but ignite if you put a match to them) suddenly melted, releasing large amounts of methane, a greenhouse gas

even more powerful than carbon dioxide. That would have heated things up very fast. If this story is correct, we need to keep a very wary eye on methane clathrates in today’s polar oceans.

It also favored narrower hips, which made childbearing more difficult and dangerous and probably means that many hominins, like modern humans, gave birth to infants that were not yet capable of surviving on their own. That would have meant that their babies needed more parenting, which may have encouraged sociability and gotten hominin fathers more involved in child-rearing.

Extreme braininess was not the first distinguishing feature of the hominins. Bipedalism was.

Among the finds of Eugène Dubois were decorated mussel shells, dated to five hundred thousand years ago, that look suspiciously like simple forms of art.

The aliens’ instruments would also have shown that oceans were getting more acidic, the atmosphere was warming, coral reefs were dying, and polar ice caps were shrinking. Biodiversity was declining so fast that some of the alien biologists might have wondered if this was the start of another mass extinction.

We even have the power, if we are foolish enough, to destroy

much of the biosphere in just a few hours by launching some of the eighteen hundred nuclear missiles that remain on high alert today. No single species has had such power in the four-billion-year history of the biosphere.

Human language is powerful enough to act like a cultural ratchet, locking in the ideas of one generation and preserving them for the next generation, which can add to them in its turn.16 I call this mechanism collective learning. Collective learning is a new driver of change, and it can drive change as powerfully as natural selection. But

because it allows instantaneous exchanges of information, it works much faster.