"The sun rose in Paderborn, with very peevish gesture. She had to indeed carry out an annoying deed. To light the dumb earth." - with these words from "Germany - a winter fable" Heinrich Heiner gives our earth an overly enlarged significance, even though in his bitter verses he had little else left for her. The sun pours only one tenth of a milliard of its light towards us - and more than a half of that is swallowed up or reflected back to space by our atmosphere.

Every square meter of the earth's surface receives on average only around 1700 Kilo Calories of energy in the form of visible light per year. Most of this turns into heat and sooner or later leaves the earth again as Infrared rays.



However, single-celled organisms managed already around four million years ago, to capture a small part of this light energy and live from it. Soon other beings learned to feed themselves on this organisms and therefore indirectly from the sun. The sun's energy would become a life-giving rays, whose countless ramifications feed the various of life on our planet. This ray is denied only the original single-celled organisms, who live deep under the surface of the earth or around volcanoes, and use geochemical processes as their energy source.

Energy is the ability to perform work. It cannot be created or destroyed, but only change from one form to another: from light to heat, from movement to electrical current - and from this to almost all other forms. the Kilo Calorie ist officially an outmoded unit for energy, but still usable in public. A Kilo Calorie can warm up one litre of water by one degree celcius - and support a walk of 13 metres or life for one minute. Under the false sign of "Calorie" countless people suffer to burn these off and strive for the bizarre slim ideal.

So much that we also enjoy the warming light of the sun - it cannot feed us directly. Every hungry tropics inhabitant is a modern Tantalus. Only plants and photosynthesising single-organisms with the magic wand of light are able to turn carbon dioxide and water into organic biomass. These deliver fuel for plant-eaters, for the fire of their cells' breathing and therefore energy for living. For the plant-eater this type of parasitism is expensive: they can use around a tenth of the light energy saved in plants for their own biomass. This is because they need energy to move and hold their temperature and chemical balance of their body constant. Therefore a kilogramme of plant nutrition often offers fewer calories than a hundred grammes of meat. The energy need of predators is even larger, because they use a lot of energy to travel long distances to hunt their prey.

The seepage of the sun's energy in this food chain is dramatic. In the free nature, plants save - in the normal fun of their lives - only a half percent of of the sun's energy they receive as biomass, while plant-eaters around one hundreth of a percent and predators another ten times less. Therefore we know such large herds of reindeer or antilopes, but not of tigers or leopards. It is even worse for animals that prey or feed on other predators. A predator who mostly eats leopards has to put itself so far back in the queue of sun's light that it could never increase its numbers. It is therefore no wonder that the leopard has no natural enemies. These remorseless rules of the food chain go also for us humans. Every one of us must take around 700 000 Kilo Calories of chemical energy in the form of food, in order to lead a normal and healthy life. As vegetarians the residents of Zurich could feed themselves with less than a hundred square kilometer agricultural land, while with a pure meat diet the neede land would be - and the price of the food - around five to ten times as much.


The strive for the sun's energy has also affected the development of man's culture. As hunter gatherers our nomadish ancestors had to cross long ways in order to ensure they got their share of the sun's energy. Agriculture and intensive domestication of animals allowed them to travel less, settle, establish cities and develope a higher culture. In order to produce evermore nutrition from smaller land masses, we use mighty amounts of water, artificial fertilizers, pesticides and crude oil. In order to gain one Kilo Calorie of nutrition, we often have to burn one Kilo Calorie of crude oil. Our industrial food production has become a grotesque machine that feeds on oil.

Our genes also aid us in our search for energy from the sun. An example are two closely related Ariaal-Sippen of Kenya. One group are nomadish stock breeders in the mountains and the other settled farmers living in low lands. A rare gene that brings out aggression, lack of concentrationm impluse and hyperactivity in humans is found mostly in the nomadish group in the well-fed and muscular, whereas in the settled farmers, mostly in the under-nourished and weaker-muscled men. This suggest that this gene variety is an advantage for nomads and the other way around a disadvantage for the settled farmers. Being implusive, ready to attack and the ability to react quickly can help nomads to defend their herds, find new grazing land or as children learn life's necessities in a life on the move - and ensure they get enough nutrition. In a village community these characteristics would be a hindrance.


We humans have come forward in our waiting list for the sun's energy: with the taming of fire we tapped into energy from the sun that light-using beings had saved over years or even millions of years. And with wind and water mills, solar cells and solar energy farms we jumped to the top of the queue. However, first spliting teh atom gave us access to energy that is not from our sun. Perhaps one day we will succeed in making an artificial sun from splitting atoms in fusion reactors. This would give us warmth and electricity on our dumb earth, but not enough light. The life-giving rays of the natural sun light can never be replaced.