Excerpt from Thom's "The Last Hours of Ancient Sunlight: We're Made Out of Ancient Sunlight".
"The Sun, the hearth of affection and life, pours burning love on the delighted earth."
—Arthur Rimbaud (1854–1891)
In a very real sense, we’re all made out of sunlight. Sunlight radiating heat, visible light, and ultraviolet light is the source of virtually all life on Earth.
Everything you see alive around you is there because a plant somewhere was able to capture sunlight and store it.
All animals live from these plants, whether directly (as with herbivores) or indirectly (as with carnivores, which eat the herbivores). This is true of mammals, insects, birds, amphibians, reptiles, bacteria...everything living. Every life form on the surface of this planet is here because a plant was able to gather sunlight and store it, and something else was able to eat that plant and take that sunlight-energy in to power its body.
In this way, the abundance or lack of abundance of our human food supply was, until the past few hundred years, largely determined by how much sunlight hit the ground. And for all non-human life forms on the planet, this is still the case—you can see that many of the areas around the equator that are bathed in sunlight are filled with plant and animal life, whereas in the relatively sun-starved polar regions there are far fewer living creatures and less diversity among them.
The plant kingdom’s method of sunlight storage is quite straightforward. Our atmosphere has billions of tons of carbon in it, most in the form of the gas carbon dioxide, or CO2. Plants “inhale” this CO2, and use the energy of sunlight to drive a chemical reaction in their leaves called photosynthesis, which breaks the two atoms of oxygen free from the carbon, producing free carbon (C) and oxygen (O2). The carbon is then used by the plant to manufacture carbohydrates like cellulose and virtually all other plant matter—roots, stems, leaves, fruits, and nuts—and the oxygen is “exhaled” as a waste gas by the plant.Many people I’ve met believe that plants are made up of soil—that the tree outside your house, for example, is mostly made from the soil in which it grew.
That’s a common mistake, however—that tree is mostly made up of one of the gasses in our air (carbon dioxide) and water (hydrogen and oxygen).Plant leaves capture sunlight and use that energy to extract carbon as carbon dioxide from the air, combine it with oxygen and hydrogen from water, to form sugars and other complex carbohydrates (carbohydrates are also made of carbon, hydrogen, and oxygen) such as the cellulose which makes up most of the roots, leaves, and trunk.
When you burn wood, the “sunlight energy” is released in the form of light and heat (from the fire). Most of the carbon in the wood reverses the photosynthesis.The small pile of ash you’re left with is all the minerals the huge tree had taken from the soil.
Everything else was gas from the air: carbon, hydrogen and oxygen.Animals, including humans, cannot create tissues directly from sunlight and air, as plants can. Thus the human population of the planet from the beginning of our history was limited by the amount of readily-available plant food (and animals-that-eat-plants food). Because of this, from the dawn of humanity (estimated at 200,000 years ago) until about 40,000 years ago, the entire world probably never held more than about five million human inhabitants. That’s fewer people worldwide than Detroit has today.I suspect the reason for this low global census is that people in that time ate only wild-growing food.
If sunlight fell on 100 acres of wildlands producing enough food to feed ten people—through edible fruits, vegetables, seeds and wild animals which ate the plants—then the population density of that forest would stabilize at that level. Studies of all kinds of animal populations show that mammals—including humans—become less fertile, and death rates increase, when there is not enough food to sustain a local population. This is nature’s population control system for every animal species: population is limited to what the local plant/food supply can feed.Similarly, people’s clothing and shelter back then were made out of plants and animal skins which themselves came to life because of “current sunlight,” the sunlight which fell on the ground over the few years of their lives. We used the skins of animals and trees (things that had consumed sunlight in recent years) to construct clothing and housing. All these are made from relatively current sunlight.