Chapter energy and technology the enhancement of skin

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5.1. The enhancement of skin

A million years ago, in the mild environment of the inter-glacial periods, upright 2-legged proto-humans (hominids) began to roam the fields and forests of Africa, or East Asia, as foragers and collectors of seeds, nuts and fruit, with an occasional meat supplement when they encountered a recently killed beast and could scare away its killer. At some point the proto-humans learned to hunt larger animals, always in groups because they were physically slower and weaker than any of the other predators.

But it seems that (thanks to organization) they developed a capacity to run for longer distances than the faster four legged creatures (like antelopes) that they hunted. The antelope would run away when the hunting party came close, but only far enough to be out of sight. Then the antelope would pause to rest until the hunters came again. And so it continued until the chosen antelope was exhausted and could run no further.

For purposes of long-distance running, heat dissipation by evaporation is crucial – as any long distance runner will tell you – and bare skin is far more efficient at heat dissipation than fur. Bare skin and widely distributed sweat glands became an evolutionary advantage. It enabled hairless hominids to hunt (and travel) during the heat of the day when the large predators with inefficient heat dissipation mechanisms were inactive and the large animals like rhinos, hippos and elephants lounged in the water. (N.B. have you noticed that your dog can only sweat through his tongue?)

It is true that we humans, like other animals, come into the world naked. But we do not stay that way for long. At some later time back in the ice ages, our increasingly hairless ancestors, being cold when they were not running, had the bright idea of covering their bare skins with the skins of other animals. Thus clothing was invented. I know not when this happened, but the link between hairlessness and the use of animal skins seems obvious.

The caves where hairless hominids lived during the glacial epoch were, of course, also another form of protection from large predators of the night. When the ice melted, people learned how to create artificial caves, or huts. Groups of huts became villages, which soon acquired walls. Skin by another name, also thanks to organization and communication.

5.2. The taming of fire

At some point primitive proto-humans made a huge leap forward by capturing and taming fire. This seems to have occurred between 400,000 and a million years ago. We can imagine the bold leader of a family group or tribe such as Sinanthropus Pekinensis grab a burning branch from the flames that engulfed a tree ignited by a lightning bolt. He bravely carries it to his cave or hut. After getting over their initial fear, the members of his tribe begin to guard and nourish the fire, to keep it alive.

Fire was an important element in ancient religion, especially Zoroastrianism, which was the main religion in Persia before the Muslims. For Zoroastrians Baku, and several other places in the Caucasus where there were “eternal flames” were holy places. Marco Polo remarked on this in his journeys. According to the Iranian Ferdowski’s epic poem Shahnameh (c. 1000 AD):

“One day Hushang reached a mountain with his men

And saw afar a long swift dusky form

With eyes like pools of blood and

The smoke from whose jaws bedimmed the world

Hushang the wary seized a stone

Advanced toward the beast and hurled it royally.

The world-consuming snake escaped

But the stone struck on a larger

And, as both shivered,

Sparks issued and a dried bush was set ablaze.

Fire came from its stony hiding place

And again, when iron knocked.

For such a radiant gift

The lord of the world thanked God.

This lustre is divine said he to his people

And you, if wise, will hold it sacred.

Making fire a cynosure for all to behold...” [Wikipedia, “Zoroaster”]
For hunters and gatherers, fire provided protection at night, even from large fierce predators like tigers, bears or wolves. (We now realize that neither bears nor wolves actually hunted humans for food – they were competitors, not predators, notwithstanding the occasional conflict. But fire was especially effective at scaring off night-hunting members of the cat family.

People learned more and more ways to use the heat from fire (and how to start one). Protection against cold was surely one of them. Fire encouraged family groups or tribes to stay in one location, which was beneficial for the safety of young children and nursing mothers. Roasting meat (to soften it and make it more digestible) and, later, making bread from the edible seeds of certain grasses were early uses. Some foods had to be cooked to be eaten at all. Cooking added to the availability of some nutrients.

It has been suggested that before cooking, humans had to do a lot more chewing – up to 50% of waking time – whereas after cooking, the need for chewing declined drastically. This had the further benefit of reducing the need for big teeth for grinding and large guts for digestion, which paid off in other ways.

Fire was also useful for hardening the points of spears and later still, for making clay pots to hold water or other fluids. Fire was also the only source of light, after the sun had set. More and more tribes and villages kept an “eternal flame” going. Gradually, the benefits these innovations concerning the use of fire spread among all the tribes of men.

William Nordhaus has estimated that, at the time of Peking man (500,000 years ago), one hour of labor would suffice to gather and trim 10 pounds (4.5 kilograms) of firewood – after drying {Nordhaus, 1998 #7666 Appendix}. Thus 200 hours of labor for wood-foraging would have yielded a ton of dry wood yielding 5 million Btu of thermal energy (heat) when burned. At 0.69 lumen-hours per thousand Btu – based on actual measurements by Nordhaus (ibid) with a Minolta TL-1 illuminance meter – burning this amount of firewood in a crude fireplace would have produced 3460 lumen-hours of light. That is the mount of light produced by a standard 100 watt incandescent light in 2 hours and 52 minutes. In other words, 200 hours of labor, more or less, would have been needed to provide enough fire-light to read this book. Sorry for the confusing un-metric units, but please blame Nordhaus.

Some of those prehistoric experiences have been passed down as myths and legends. In Greek mythology a man named Prometheus stole the fire from Mount Olympus, the residence of the gods, and brought it to the humans on Earth. Zeus, the Godfather, punished Prometheus cruelly by chaining him to a rock, where birds pecked at his liver (which seemed to grow back every night). But Prometheus’ gift gave humans power to resist the angry and fickle Gods and saved them from doom. Here is a quotation from Hesiod, 700 BCE: “Fire is the basis of all craft. Without it, Man could not persist.”

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