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Humans seem to need outside energy

For starters: Without the energy to cook their food, humans would have much more limited food supply and spend half the day eating.

By Gail TverbergGuest blogger / September 7, 2012

In this June photo, Edalyn Garcia plates fried broccoli during a fundraiser in which the six-person culinary Olympic team from Coos Bay, Ore., served community members a two-course meal similar to what they will prepare during the Olympic competition this fall. Using energy to cook food has given the human race a much more varied diet and more time to develop it.

Jessie Higgins/The World/AP/File


Strange as it may seem, humans seem to have evolved in a way that we have a need for external energy, such as energy from burning wood or fossil fuels. While the evidence is not 100% certain, it appears that we learned to use fire long enough ago that it is now  necessary for our food to be cooked. Otherwise, in many climates, we would need to spend half the day chewing our food, and we would not be able to do much besides gather food and eat it. (People on raw food diets get around this issue by using a blender, which also uses external energy.)

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Gail Tverberg, an actuary with a background in math, analyzes energy and financial matters from a perspective that the world has limited resources. For more of Gail's posts, click here.

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There are other evolutionary deficiencies as well: How do we deal with our lack of fur? How do we deal with our evolutionary dental problems? How do we deal with “survival of the fittest”? If we want our children to live, we continually need more food for our growing families. Cooked food gives more choice of food supply. We don’t think of humans as having instincts, but like dogs, we have a tendency toward hierarchical behavior, and this affects our need for (or at least “want for”) external energy.

An additional issue, now, of course, is that the world’s population is over 7 billion people. Even if we had not evolved to require using external energy, cooking our food makes many more types of food available, and is from this point of view much more practical than raw food. Cooking food does not in itself take a huge amount of external energy, but once we had learned the skill of using external energy, it opened new doors for other applications.

In this post, I will explain how these and other evolutionary issues relate to mankind’s need for external energy, such as wood, or gasoline, or electricity. 

Humans’ Need for an Outside Energy Source

According to Todar’s Online Textbook of Bacteriology, energy is important for all living organisms. Plants and animals literally can’t live without a source of energy. Except for humans, plants and animals get all the energy they require from natural sources: from the food that they eat, or from sunshine through photosynthesis. Some organisms derive the energy they need through oxidation of inorganic compounds. Because of these natural mechanisms, these species have everything they need for survival, without requiring clothing or shelter, or other types of goods.

We can see how different humans are from other animals by comparing ourselves to large primates such as chimpanzees. Large primates spend much of their day gathering and eating raw food. They are not as intelligent as humans, and they mostly live in trees, so as to be able to avoid predators. This limits their choice of food supply. Their total number is far smaller than humans, because they need to stay in habitats to which they are adapted. The number of large primates varies by species (100,000 to 200,000 chimpanzees, about 130,000 gorillas, and fewer than 250,000 Gelada baboons according to the National Primate Research Center), but is always far fewer than the 7 billion humans in the world.

The shift away from behavior similar to that of other primates seems to have started after humans learned to control fire and learned to cook food. Chris Organ and others have shown that for a primate the size of humans, cooking food decreases the amount of time that must be spent chewing food from 48% of daily activity to 4.7% of daily activity. With so much more free time, the way an animal spends its time can change dramatically. Those changing to cooked food could do more hunting, and because of this change, include more meat in the diets. This would improve diets in another way.

It is well-known that cooking makes grains much easier to digest. Grains are a major agricultural crop, so cooking helped enable the transition to agriculture, around 10,000 BCE.  With the transition to agriculture came the possibility of much higher world population.

Harvard biological anthropologist Richard Wrangham in “Catching Fire: How Cooking Made Us Human” sees evidence of evolution of adaptation to a cooked food diet as early as 1.9 million years ago. When Homo Erectus appeared at that time, teeth and guts were smaller than in predecessor species, and brains got larger. He speculates that the energy that had previously gone into digestion might have gone into brain development.1

With  the evolution to smaller teeth, smaller gut, and bigger brains, humans have a real need to cook at least part of the food they eat. So outside energy for cooking food is one realneed for the 7 billion people on our planet today.

Other Reasons Outside Energy Is Desired

Humans evolved without fur. Richard Wrangham in Catching Fire argues that fire allowed humans to evolve without fur, because a hairless animal can warm itself by a fire. A hairless animal is at an advantage chasing animals because it can dissipate heat much more quickly, allowing a hairless animal to catch one with fur by chasing it until it drops of heat exhaustion. The down-side of having no fur is that humans need at least some type of protection from the outside elements, especially if humans move to locations outside the tropics. Such protection might come in the form of clothing or shelter, or both. Outside energy would be helpful in creating food and shelter, but not as essential as for cooking food. Here again, being able to cook was helpful, because the reduced chewing time permitted more time for creating clothing and shelter.

Humans evolved with little defense against predators, except their intelligence. While other primates could climb trees, humans could not. They couldn’t fly or swim either.  Here too, outside energy sources were helpful. According to Wrangham, if early humans were gathered around a campfire, and a predator approached, one means of defense was to swing a fiery log at the predator. A group of humans could be protected from predators overnight by having a watchman with access to burning logs stay up all night. Eventually, humans learned how to use outside energy sources to build transportation of many types: automobiles, trucks, boats, and airplanes, to make up for deficiencies in the area of self-transportation.

Humans gradually found other ways that energy could be used to help overcome their evolutionary deficiencies. About 75,000 years ago, humans discovered that by heating rocks before they made tools from them, tools could be made more efficiently, and with a sharper edge (KS Brown et al, 2009). They later discovered that metals could be created with the use of external heat, expanding the type of tool that could be made. Humans evolved with hands that were more dextrous than those of other animals, so being able to produce good tools gave humans an advantage over other animals.

One deficiency of human evolution is that our tooth enamel has not evolved to withstand a diet high in starches. (PS Unger, 2012) Dentistry, which uses energy in many forms, including metal for tools and electrically operated X-ray equipment, helps provide solutions to these evolutionary deficiencies.

Humans, with their upright posture and large head sizes (because of large brains) have tended to have difficulty in childbirth, resulting in many deaths. Modern medicine helps overcome the problem of excessive mortality in childbirth. It, too, uses a lot of external energy, including metal tools (created using heat), sterilization, and medicines made from petroleum products.

Humans Outwitted Survival of the Fittest

In the natural order, each mother gives birth to more offspring than are needed to survive to maturity. This tends to work very well, because the offspring that are best adapted to the environment tend to survive to adulthood. As changes occur, such as a change in climate, or an increase in a particular type of predator, the offspring that are most able to handle the new environment are the ones who survive.

Humans, because of their intelligence, have found ways to defeat survival of the fittest.  As areas get overpopulated, humans have moved to areas where they have a better chance of survival. Humans have found ways to increase food supply, through the use of fertilizers, pesticides, irrigation, and refrigeration, all of which require fossil fuels. They have developed trade, so that so areas with shortfalls can benefit from surpluses elsewhere. Humans have developed a world financial system, which has helped enable world-wide trade. The financial system has also allowed investors to pay for goods after they are put into service, so that the cash flow resulting from an investment can be used (after the fact) to pay for the cost of the investment. This enables investment, and faster use of resources, including energy resources.

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