Monday, January 21, 2013

Big Brains

There’s probably no single event more significant in the history of human evolution than the harnessing of fire. Many species make and use tools, but only humans control fire. Fire provided early humans a means to protect themselves from predators. Fire provided humans with warmth and light, and expanded productivity into the night. Socializing around a campfire may have been an essential part of human development.
   Perhaps the biggest benefit of fire was for cooking. Cooking food provided better nutrition and made food safer to eat. Cooked meat was easier to digest because less energy was spent digesting the tougher proteins and connective tissues.
   Cooking plants that contained starches made the complex carbohydrates they contained more digestible so that more energy could be absorbed from them. The human digestive system has evolved after we started eating cooked foods: our teeth, jaws and digestive tract have all gotten smaller, allowing our developing brain to have a greater share of the food energy taken in. Eating cooked food helped provide the extra energy required to support a hunter-gatherer lifestyle.
   The earliest known evidence for the controlled use of fire comes in the form of ash and charred bone excavated from a South African cave that is known from previous digs to have been occupied by early man. These materials were found alongside stone tools in a layer dating back about a million years.
   Although modern humans are the only human species alive today, originating about 200,000 years ago, other human species once roamed the Earth, such as Homo erectus, which arose about 1.9 million years ago.
   Some anthropologists think that Homo erectus was cooking as far back as 1.9 million years ago and was the reason that they experienced major brain expansion at that time. Others think that brains got bigger just by the introduction of meat into their diets and that while there was the opportunistic use of natural fire, it was not until about 300,000 to 400,000 years ago that early humans fully mastered the use of fire.
   One thing is certain—our brains have tripled in size over that last two million years. But evolution doesn’t say anything about whether larger brains are good or bad, just that it happened. Author Kurt Vonnegut believes that our brains have over-evolved: “Our brains are much too large. We are much too busy. Our brains have proved to be terribly destructive.”
   Vonnegut explored this theory in his 1985 book Galapagos where our big brains have brought civilization to the brink of destruction. The last humans ironically survive because they get stranded and isolated on the Galapagos Islands made famous by Charles Darwin. They spend the next million years de-evolving.
   As evidence for his theory, Vonnegut says that big brains invented nuclear weapons and the Third Reich. Even Einstein noted that “He who joyfully marches to music rank and file, has already earned my contempt. He has been given a large brain by mistake, since for him the spinal cord would surely suffice,” indicating his belief that war is a huge step backwards in human evolution. And while I’m more optimistic, I didn’t witness the bombing of Dresden firsthand as did Vonnegut, nor did I have to flee my home and country out of fear for my life as did Einstein. Food for thought…

No comments:

Post a Comment