Getting Down to Business
In order to understand the economy of a single cell, we need to grok how small these entities are. It takes some effort to internalize the new scales of science that extend far beyond our direct sense perceptions. In that sense, most of science is by definition counter-intuitive. You can’t see much of what science is about—it’s too large or too small, too fast or too slow. The universe is as many orders of magnitude smaller than us as it is larger. And it is at least as instructive for the existentialist in you to stay awake at night pondering not just how big the universe is, but rather how small.
The diameter of a single hydrogen atom—one proton, one electron, and a lot of empty space—is approximately 0.1 nm (nanometers). Just to be clear, one nanometer is a billion times smaller than one meter (10-9 m).
Amino acids—small molecules essential to cell chemistry and varying in atomic composition —are approximately 0.8 nm in size.
DNA, the molecule deoxyribonucleic acid, is about 2 nanometers wide but varies dramatically in length. The longest human DNA is found in chromosome 1 and consists of 220 million base pairs. When stretched out it would be about 85 millimeters long and very, very thin. In terms of length, human DNA has nothing over the marbled lungfish, which clocks in at a 133 billion base pairs. At the other end of the DNA spectrum is the diminutive bacteria Carsonella ruddii with the smallest known genome containing 159,662 base pairs. DNA, as we will explore below, has an aperiodic property that allows it to encode information for cell construction and replication.
Prokaryotes—single-cell bacteria and archaea, more about that later—are the smallest and ur-unit of life. The smallest bacteria are about 150-250 nm. The bacterium E. coli, part of your intestinal microbiome, measures up at approximately 2 µm (micrometers or microns). Here we have moved up in the scale a thousand fold, from nanos to microns, from 10-9 m to 10-6 m.
Needless to say, it takes imagination on our part to grasp these orders of magnitude jumps in scale. Think of one nanometer as somehow equivalent to $1. Our hydrogen atom would cost about ten cents at the local supermarket. Fortunately, there is an abundance of hydrogen and it doesn’t take up a lot of shelf space. A single bacterium, the aforementioned E. coli at 2 micrometers, is available for a cool $2,000. Your gut contains trillions such cells, so stock up. At the millimeter scale, we can actually see what we’re buying, if we look carefully. The price of a C. elegans, a 1 mm transparent round worm used widely in genetic and neuroscience research, is going to cost you $1,000,000. A shopping cart full of food would cost you tillions of dollars.
Of course, this analogy is technically misleading—meters and dollars are not equivalent. The analogy, however, illuminates more than just the scale of size from nanometers to meters. It also reminds us that there is always an energetic cost in growing complexity. Bigger entities really are more expensive. Evolving complex cells required orders of magnitude more atoms, and orders of magnitude more energy, to create, maintain, grow, reproduce, and evolve. There is always a cost.
Energy is the currency of the Universal Central Bank, guaranteed by the Second Law of Thermodynamics. All of the regional banks—astronomy, chemistry, biology, technology, economics, culture—can create their own energy currencies and markets because of this guarantee. The Universal Central Bank does not offer fixed rates of return, but rather variable rates of losses in a predictable flux that impacts every domain at every scale. Energy dissipates. Entropy grows. That’s not a problem; that’s the singular opportunity.
The words of the physicist Arthur Eddington come to mind: “Suppose that we were asked to arrange the following into categories—distance, mass, electric force, entropy, beauty, melody. I think there are the strongest grounds for placing entropy alongside beauty and melody, and not with the first three. Entropy is only found when the parts are viewed in association, and it is by viewing or hearing the parts in association that beauty and melody are discerned.”
The Central Bank of Chemistry
To grasp opportunity, beauty, and melody in life, we need to review some basic chemistry. Atoms—composed in the first order of protons, neutrons, and electrons—are the building blocks of chemistry. Most of the atoms in the periodic table of elements were created by stellar fusion in giant fast burning stars. When these massive stars exhausted their fuel, they collapsed and blew up in supernovae. The remains of these supernovae then gave rise to new stars containing the possibilities of complex chemistry. Our solar system is such a place—the material remains of a colossal star that died in a dramatic explosion, perhaps 7 billion years ago.
It took a lot of energy to fuse simple atoms—hydrogen and helium—into heavier atoms. The iconic equation—E=mc2—expresses not just the incredible power of a nuclear bomb converting a wee bit of matter into a whole lot of energy, but also the challenge of converting a whole lot of energy into a wee bit of matter. The latter is how particle physicists interrogate the subatomic realm of matter at CERN and other linear accelerators around the world.
Chemistry follows different rules than nuclear physics. In normal chemistry, elements in the periodic table are indestructible. Atoms can and do join together to form molecules. Molecules can and do fall apart, but the atoms that constitute the molecule retain their basic identity before, during, and after these transformations. That identity—hydrogen, helium, oxygen, carbon, iron, and all the rest—is determined by the numbers of positively charged protons in the atomic nucleus along with an assortment of neutrally charged neutrons.
Chemistry is mostly about the affinities of electrons. As described by quantum mechanics, electrons exist in clouds of “probability space,” albeit in distinct orbitals, around a positively charged nucleus. Standing between the nucleus and the electrons is a whole lot of empty space and a powerful magnetic fields.
Imagine a simple hydrogen atom—one proton and one electron—as a major league baseball stadium. Think of the proton as a baseball on the pitcher’s mound. The electron would be something smaller than a flea somewhere at the furthest reaches of the stadium; and this flea is moving at extraordinary speeds. The electron of a hydrogen atom covers about 2,200 kilometers per second in its frenetic orbit around the single proton nucleus of hydrogen. It helps to be really small if you want to go at these speeds.
Look around your immediate surroundings—books, chairs, tables, walls, floors, windows, computers, and your hand. Lots of reliably solid objects. Don’t think of matter that way. Instead, try to grok the magnetism of ecstatic electrons vibrating with their nuclei. It is this electromagnetism that gives us the illusion of a world of solid objects, when those objects around you are actually mostly empty space. Even when tightly in packet in objects like rocks, atoms are always busy. While not alive, atoms are certainly animate, if that makes sense. On the atomic scale, nothing is inert and unmoving. Everything vibrates with intense activity.
There is a kind of electron law of supply and demand. Following their affinities, busy electrons are promiscuously exchanged and shared between atoms, joining together elements into new compounds. The electrons are looking for a place to rest that is not as frantic as where they just were. The logic of the outer electron orbitals determines if, whether, and how atoms combine into molecules and alternately how molecules fall apart. Some elements in our periodic table are more stable. Some more reactive. It’s in the nature of the things.
When an electron leaps to another atom, the donor atom’s electromagnetic charge is reduced—making it more positive, while the recipient’s negative charge is increased. The participants in this electron exchange may be strangers passing in the night. Often as not, though, their newly found positive and negative valences create an instant bond between the two—opposites attract in an ionic bond. Electron transfer is one of the ways that atoms turn into molecules.
Sodium chloride is the textbook example of such a molecule (i.e., table salt). The sodium atom (Na) loses an electron to chlorine (Cl). Na is now positively charged. Cl is now negatively charged. The two elements are bound together by their positive and negative attraction—an ionic bond.
Na + Cl → Na+ + Cl− → NaCl
Electrons can also be shared between atoms. This is called a covalent bond. The textbook example is water (H2O). In water the electrons from the two Hydrogen (H) atoms come to orbit around the nuclei of both the oxygen and hydrogen atoms.
H2 + O → H2O
Sharing electrons creates a stronger and more enduring bond than the positive and negative attractions of ionic bonding. Complex molecules typically employ both kinds of bonds. The economies of chemistry are a series of limited partnerships (covalent bonding) and merger acquisitions (ionic bonding).
Some atoms, carbon for instance, are especially good at forming covalent bonds with other atoms. Life necessarily harnesses the chemical properties of the carbon atom to construct complex molecules. The formula for methane is one carbon atom bound to four hydrogen atoms (CH4). Having filled its outer orbital with the shared electrons from the hydrogen atoms, the carbon and hydrogen atoms are more stable and less reactive in the new molecular form.
Oxygen, on the other hand, is reactive by its nature. Oxygen is always out to dump an electron or two on its neighbors. When it can, oxygen is said to “oxidize” other atoms and molecules. This combustion can happen fast or slowly, spontaneously or induced. The mere presence of oxygen causes iron (Fe) to slowly rust.
2 Fe + 3 0 → Fe2O3
A candle, on the other hand, must be induced to burn with a match. The rapid oxidization of the wax generates heat and light. Both reactions are examples of combustion, though the oxidizing of iron much slower. It is the same basic chemical process in all living cells, though not necessarily with oxygen as the reactive. Other elements can also do duty. A key oxidation reaction process inside of complex cells is respiration, more about that later. All chemical reactions export heat energy to the surrounding environment; the life inside us and all around us is the most dramatic example thereof.
When oxygen reacts with methane, the methane is oxidized, forming carbon dioxide and water. This reaction gives off heat. It is exothermic.
CH4 + 2 O2 → CO2 + 2 H20 + Energy
Actually these reactions at the atomic scale never really happened in the singular. Rather, chemical reactions occur with millions or billions of their cohorts nearby, experiencing more or less simultaneously the similar bonding reactions and a common flux of energy in which entropy always grows in the surrounding environment, as guaranteed by the Universal Central Bank.
Molecules greatly complicate the affinities and possibilities of electrons and their atoms. For instance, there are 20 different amino acids with a mean of 19.2 atoms per molecule. Amino acids combine by the hundreds to form proteins. A mid-sized protein might contain some 400 amino acids. This single protein molecule thus contains 8000 atoms plus or minus—hence the nomenclature “macromolecule.” The elements involved are primarily carbon, hydrogen, oxygen, and nitrogen—held together by both covalent and ionic bonds. The geometry and intensity of these affinities determine how proteins fold into particular shapes that perform specialized cellular functions. Even the smallest single cell economies contain many millions of proteins inside their cytoplasm.
The trade in electrons drives the economies of chemistry. Unlike human currency, the medium of exchange is not a fiat currency—paper money—with no intrinsic value. Instead, the Central Bank of Chemistry is also backed by the Second Law of Thermodynamics.
Save it to say that some chemical reactions release energy to the environment—exothermic. And other chemical reactions consume energy from the environment—endothermic. Many do both, up and down energetic scales and embodied complexities. It takes a match—endothermic—to start a campfire. The sustained combustion of the wood, however, is a net exothermic chemical process dissipating heat, light, and gases in the environment. If we include the entire energy life cycle of the tree from which the wood came, then we have a net endothermic event. It took orders of magnitude more solar energy to grow a bundle of firewood than is released in the fire itself.
Chemical complexity requires two things. First, it requires a source of energy in order to arrange atoms into molecules. Having created more complex molecules, it can also require energy to break them down. Second, it requires a heat sink, a place to discard disorder, a garage dump to dissipate energy. On the planetary scale, the cold of outer space is the Earth’s heat sink, even as the sun is our primary heat source. On the chemical scale, the local environment of the system will do just fine. Both the energy sources and the energy sinks are found in the surrounding environment of all complex systems. In all cases, energy is consumed from and release to the environment in order to create, maintain, rearrange, and break down molecules.
Electromagnetism is what holds the world together, at least the scales that matter most to humans. Technically, there are four fundamental nuclear forces—electromagnetism, gravity, strong nuclear force, and weak nuclear force—but at our biological scale electromagnetism does the work of normal chemistry. The electromagnetism of chemistry drives the energetic flux that animates life and the growth of complexity in the world around us.
The Central Bank of Chemistry is always depreciating its energy reserves, a fact on the macro-level of Big History that we can happily ignore for a couple billion years. We live on a tiny thermodynamic eddy in the universe where free energy is plentiful and complexity has the possibility of running up hill. The monetary policies of our planet are based on the sun, the deep cold of space, and the fundamental laws of physics. Investors can count on these as a reliable partner in terrestrial markets for at least two billion years.
The Currency of Life
The currency of cell biology is the molecule ATP—adenosine triphosphate. ATP is an energy delivery system, each molecule a little packets of energy. Like money in our economy, ATP circulates throughout the cell. Unlike money, it needs to be reminted after each transaction. The molecular remains of spent ATP are quickly recycled to make more ATP. All life—from bacteria to blue whales—uses ATP to energize its creative dynamic.
Joining amino acids together to make a protein takes about 5 ATP molecules for each bond. Constructing a modest sized protein of 400 amino acids would consume about 2000 ATP molecules. From there the numbers quickly become astronomical. Protein construction occurs at a frantic pace inside a cell. When we add all the molecular activities going on inside a simple cell, we’re looking at hundreds of thousand or even millions of ATP molecules consumed per second. A human typically consumes about its weight in ATP molecules every day, but at any given moment, there are only about 250 grams of ATP in the human body. ATP is continuously consumed and recycled inside the economy of a single cell at a rate that dwarfs daily foreign currency transactions in our human economy.
The continuous minting of ATP requires chemical energy—as mandated by the Universal Central Bank. Cells take in food from the environment and then break down this food into smaller usable molecules. Electron transfer reactions then turn these small molecules, primarily glucose, into energy for cell construction.
Moreover, cells figured out how to store electrical energy by turning membrane barriers into the first batteries. In order to transport food energy in and waste out, cell membranes need to also be selectively permeable. This is achieved by protein structures embedded in the otherwise impermeable lipid membrane. One such structure oxidizes hydrogen atoms, removing the electron and using the energy therefrom to pump the remaining proton across the membrane.
Normal chemistry, we observed, was about the affinities of electrons. You don’t find unattached protons floating around in nature, as they would immediately grab an electron from its neighbor and revert back to a hydrogen atom. But in cell biology protons are the key to storing and utilizing potential chemical energy. If you collect enough protons on one side of the membrane, you’ve got a battery.
The positive valences of the protons on one side of a membrane create a powerful electromagnetic potential energy that drives the ATP synthesis and other cellular functions. How strong? The electromagnetic valence across a mitochondria membrane would scale to 30 million volts per meter, equivalent to a lightning strike. Fortunately, this occurs not at the scale of meters and megavolts, but nanometers and millivolts. This is the vital force that drives ATP production and the prodigious biochemistry of all life. The molecular machines that drives this process are not found anywhere in inanimate nature, except as mimicked in human technology.
The Business Models of Life
Life excels at capturing and concentrating energy, harnessing the chemicals in its environment, to grow and reproduce. It does so both by evolving new efficiencies, like enzymes that speed up and channel chemical reactions, and by increasing overall energy intake.
Life began about 4 billion years ago as single cell prokaryotes, which come in two families, bacteria and archaea, distinguished by their membranes and other features. Prokaryotes share many biochemical pathways, including the use of ATP. Prokaryotes have no nucleus or other membrane bound organelle. Eukaryote cells, on the other hand, have a nucleus and organelles and are usually much larger and morphologically more complex than prokaryotes. All plants and animals are eukaryotes.
Life probably first got hold in alkaline hydrothermal vents on the ocean floor, an environment rich in energy and chemical possibilities. Having figured out membranes, metabolism, and memory, early prokaryotes reproduced, evolved, and spread around the planet, developing enormous genetic diversity. Along the way the bacteria and archaea developed all the major chemical metabolic pathways. Their biochemical ingenuity allowed them to harvest more energy and matter from increasingly diverse biomes on our restless planet.
Moreover, prokaryotes have the ability to share genetic information. Genes are the architectural plans for cell construction and replication. Without genes life has no memory of itself and no capacity to compute. Prokaryotes divide into clones, but they also exchange genes through lateral transfer. Genes can be exchanged through viral transfer or simply proximity as prokaryotes give away and pick up DNA segments from their neighbors. The bacterium E. coli, for instances, has only about 4000 genes. The metagenome of all E. coli bacteria, however, may contain 18,000 genes. Indeed, the prokaryotes need not be of the same species to share genes. Keeping a lot of useless genes around is expensive, so bacteria are quick to discard unused genes and to pick up new genes that might be useful. The genomic situation between prokaryotes is so confused that some biologists think of all prokaryotes as a single species. “Simple” bacteria and archaea created the world’s first global economy of staggering complexity with its own world wide web of information sharing.
The First Agricultural Revolution
Human agriculture is all about harvesting energy from the sun through domesticated plants and animals. Bacteria figured out how to do this some 3.5 billion years ago when they invented photosynthesis. This ability to tickle a photon from the sun and turn it into food allowed an exponential growth in life beyond the finite chemical and thermal potential energy of our young planet. In the process, bacteria sculpted rocks, laid down huge sedimentary deposits, changed the oceans, and transformed the environment. Photosynthesis breathes in carbon dioxide, soaks up water, and exhales oxygen in order to create carbohydrate food molecules to fuel cell growth.
Carbon dioxide is a one of the greenhouse gases implicated today in anthropogenic global warming. Two billion years ago, the reduction of carbon dioxide in the atmosphere presented the opposite dilemma. A billion years after photosynthesis began, oxygen levels began to rise in the atmosphere. Reduced carbon dioxide and increased oxygen in the atmosphere resulted in global cooling. The Earth was soon covered with ice—a giant snowball—in what is referred to as the Great Oxidation Event.
Those prokaryotes that could not adapt to the new oxygen rich environment retreated into the anaerobic muck. Others evolved membranes that could resist oxygen and later harness its power through respiration, greatly magnifying the energy production power of the cell. It is not clear whether any lineage of prokaryotes ever actually went extinct, though their niches and numbers in which anaerobic prokaryotes could thrive changed as oxygen became more abundant. With photosynthesis and later respiration, single cell life had a new and practically unlimited source of energy fueling a great radiation of life in the terrestrial oceans.
Photosynthesis is the miracle machine that energizes all life. It didn’t start out that way, but in the ensuing eons, the baroque varieties and abundance of life were and still are founded on this molecular legerdemain. Some prokaryotes still make their living by harvesting chemical energy in their environment, as all prokaryotes did before photosynthesis, but they are a small part of the Gross Primary Productivity (GPP) of our planet’s biomass today. At the bottom of the food chain and the energy economy of our planet is photosynthesis—a process of transforming carbon and sunlight into biomass.
Prokaryotes still reign today. Their biomass probably exceeds that of all eukaryotic life. Prokaryotes have an incredible capacity to set up shop inside and on top of every surface, climate, geography, and creature on this planet. We are here today as their descendants, guests, and servants; but we—the royal eukaryote “we” including all plants, animals, and fungi—are also singularly different from the prokaryotes.
The First Industrial Revolution
Eukaryotes appear about 2 billion years ago. Unlike prokaryotes, they have a differentiated, membrane-bound nucleus and specialized organelles—mitochondria, chloroplast, Golgi apparatus, endoplasmic reticulum, a complex cytoskeleton, and more. Eukaryotes mostly engage in sexual reproduction. And while prokaryotes need not die—their daughter cells continue as clones—most eukaryotes have preprogrammed senescence built into their DNA. Eukaryotes are also usually orders of magnitude larger than prokaryotes. Prokaryotes, of course, hitched a ride as the eukaryotes diversified and radiate out eventually into all the multicellular flora and fauna of our world, including inside and on all the surfaces of your body.
The story of first eukaryotes—the lineage we share with all fungi, plants, and animals—is astounding science, the stuff of fairy tales really. It is a story told in bioinformatics and the comparative analysis of genomes in the last few decades. Once upon a time—long, long ago—some microbes made their living by eating others microbes, which turn out to be very nutritious. This was and still is all pretty normal for microbes and other living things. Everyday we eat other living things—three meals a day perhaps and a few snacks in between, unless of course you are a plant. One day, though, something strange happened that apparently only successfully happened once or twice in the history of the planet. A single-cell archeon swallowed some bacteria for breakfast, but breakfast didn’t digest.
Normally, the enzymes break down the captured microbe into byte-size food molecules. Not this time. Instead, breakfast decided that the cytoplasm of the predator cell was a good place to live and start a family. As kids we feared that a swallowed watermelon seed might grow into a new watermelon inside our stomachs. This is kind of what actually happened two billion years ago in the great microbial leap forward.
The initial acquisition and merge between the archeon and the bacterium created deadly competition inside the cell. Presumably it has been tried and failed multitude of times leaving no geological trace or contemporary intermediaries. The successful merger of two microbes— endosymbiosis—was something quite singular in evolution. It only happened once, maybe twice, in the history of our planet. The ur-eukaryote—the grandmother cell of all fungi, plants, and animals—somehow developed a complex cell with differentiated organelle, it also acquired and then domesticated a parasite resulting in an exponential evolutionary jump in the flux of energy, matter, and ingenuity—the great microbial leap forward.
Ring of Life = Prokaryotic phylogenetic tree + Symbiogenetic origins of eukaryotes
Wikimedia, Mauricio Lucioni, Anillo de la vida.png, 7 June 2014, CC BY-SA 3.0
Breakfast turned into a houseguest that wouldn’t leave and kept getting more plentiful as it reproduced. To keep up with its own reproduction, as well as the parasites reproducing in its cytoplasm, the competition had to turn into cooperation and mutual benefit. A house divided, cannot stand. The ur-eukaryote mother cell passed the DNA of the mitochondria and chloroplast along with its own DNA through reproduction to its sons and daughters, separating its own DNA inside the nucleus membrane thereby keeping it separate from the newcomers DNA. The newcomers—powered by photosynthesis—shared ATP with the host cell. Breakfast turned into a parasite, which then turned into a symbiont living inside the cell.
Over time, the newcomers evolved into organelles—mitochondria and chloroplasts. The endoybionts started getting rid of excess DNA, keeping only genes necessary for its own reproduction inside the host’s cytoplasm. Some of these discarded genes are picked up by the host cell and kept inside its newly formed nucleus. Sexual reproduction mixed things up more. Eukaryotes explore and evolve into the many possibility spaces and morphologies of life more abundant and more diverse. With the radiation of eukaryotes, the quantity of organized information-ingenuity—in the number of DNA base pairs inside cells—begins to grow exponentially.
Eukaryotic complexity can be crudely measured in the amount of DNA that rapidly accumulates inside the nucleus of cells at the time of the great radiation of eukaryotic life 2 billion years ago.
Size of Genome in number of Base Pairs
Abizar at English Wikipedia [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons
The exponential growth in ingenuity in the great radiation of eukaryotic life required also an exponential increase in the flux of energy-matter. Sexual reproduction was one of the technological innovations that helped solve this problem. Sex is how eukaryotes explored adjacent morphological possibilities in the environment. The chloroplast and mitochondria organelles inside the eukaryote cells became the energy engine of evolution. The Central Bank of Chemistry was able to dramatically grow the supply of ATP in the economy of cells energizing the great microbial leap forward.
At first the new lineage of eukaryotic microbes were single-celled creatures known as protists. They come in plant-like, animal-like, fungus-like, and mixed up varieties. Chlamydomonas reinhardtii, of instance, is a single-cell alga that reproduces both sexually and asexually, has motility and heterotrophy, like an animal, but is also capable of photosynthesis like a plant. Most protists vary in size from 10 to 100 µm (i.e, thousands of times larger than the average prokaryote).
Unlike prokaryotes, which are biochemically complex but morphologically simple, the newly incorporated eukaryotes grew in size and morphological complex. Sexual reproduction within distinct lineages of eukaryotes, and the inevitability of death, gave rise to a dramatic evolutionary radiation of diverse kinds in the history of our planet.
Eukaryotes took cooperation-competition to new levels by forming multicellular organism with specialization and divisions of labor. The prokaryotes in the environment, of course, went along for the ride with the new big kids on the evolutionary block. We see this in our own bodies, where bacteria and archaea are an essential component of our development and health, as well as disease and death. Microscopic eukaryotes evolved through natural selection into the marvelously diverse and complex fauna and flora that amaze us in nature today.
The Whole Economy of Nature
In The Origin of Species, Charles Darwin wrote of “the whole economy of nature.” We have extended the metaphor to the level of single cellular life. Economics and biology have come a long way since Darwin first used this analogy. Singled-cell prokaryotes and eukaryotes have their own laws of supply and demand involving electron markets and the currency of ATP. Specialization and division of labor was already nascent in the biochemistry of hunter-gatherer prokaryotes. The invention of photosynthesis was a kind of agricultural revolution, dramatically increasing the energy that could be harnessed to support the growing economies of life. The microscopic prokaryotes also created a global trade in DNA fragments, which continues to this day, aided now in their spread by human trade and travel. Specialization and division of labor took a giant leap forward in the industrial revolution of eukaryotes. Multi-cellular organisms took this even further.
Cells—big or small—maintain their identity through inconceivably frenetic activity. Trillions of chemical cascades occur every second inside each cell. Even the smallest of bacteria contain hundreds of million protein molecules of many thousand different types. To maintain such complexity, cells, like economies, need to take in matter and energy and dispose of waste. Cells needs to defend themselves from predation and harm, while seeking out new sources of energy and matter from their environment so they can exist, grow, reproduce, and complexify.
There are about 37 trillion cells in a 70-kilo human body (and approximately an equal number of prokaryotes—by weighing about 3 kilos). And though you may experience yourself to be unified and coherent, at times even calm and relaxed, the incomprehensible frenzy of each cell in your body continues throughout the nights and days of your life.
Life is an energy-matter and information-ingenuity processing system. It is a flux of energy-matter guided by information-ingenuity. Life has a built-in telos—survive, grow, and reproduce life more abundant, more diverse. Information is passed on to descendants in the code of DNA—a code for the many ingenuities of cell biology and evolution—which code choreographs the marvelous dance of energy-matter in the great flux of emergent complexity.
It begins and ends with energy density flows. Cells achieve a temporary homeostasis inside their membranes through a dynamic chemical-energetic disequilibrium with the outside environment. If you don’t understand bioenergetics, you don’t understand the economy of a cell, let alone the whole economy of nature. If you don’t understand energetics, you also don’t understand human economies. As we will explore in upcoming chapters, the universal formula for wealth creation is energy, matter, and ingenuity.
By changing scale, we can shift from the economic metaphor from inside a single cell to the economy of many individual cells interacting. The latter—individuals interacting—occurs in the form of microbial ecosystems as well as the rise of multicellular organisms. At this point I don’t know how the analogies best applies, what counts as an individual or a corporation, where to draw the line between microeconomic and macroeconomics, in the context of cell biology, I don’t know. But certainly, like economic markets, cell biology and cell ecologies are emergent phenomena. Many actors buying and selling make the market. One cannot predict market trends based on a single corporation or individual. Similarly, one cannot really understand the behavior of a single cell by studying a single protein, let alone a single atom. And microbial ecosystems add an order of magnitude more complexity in our level of analysis.
Cell biology and economic markets are examples of complex adaptive systems. The economy of cells, however, is more than just a metaphor for economics. Complexity theory, and its cousin chaos theory, allows us to discover common patterns in disparate natural phenomena. Star formation, cell biology, genomics, ecology, earthquakes, floods, neuroscience, and economic markets turn out to share common patterns. Applied big history is an attempt to build those connections between domains and disciplines, in this case to learn how the physical and biological patterns appear also in economics and finance.