"FOOD FOR THOUGHT"1
A most interesting theory of evolution contends that The Driving Force 2 for the development of human brains and intelligence always was and still is food. Professor Michael Crawford and his co-author David Marsh contend that random changes in DNA (the genetic code in our cells) is far from an adequate explanation for the changes in the forms of life over the course of evolution. These random effects, along with survival of the fittest, occurring in incremental changes over the millennia, would have meant mathematically, that in the resulting organisms, the probability of the development of a human brain would have been, in any practical sense, infinitely small. Actually, evolution has occurred in great spurts when the "chemical substrates," in other words, appropriate food, became abundant and then life forms have adjusted and changed little over millennia. Survival of the fittest comes into play when the food resources become scarce.
Life forms have responded marvelously in the many situations when the necessary resources were abundant. One tremendous change occurred when, in the course of their metabolism, the algae in the oceans had given off sufficient oxygen so that oxygen-using animals could develop. There was a great abundance of nutrients and the explosion of species was amazing.
Structural fats (omega 3 and omega 6 fatty acids) initiated another great increase in the complexity of animals—they permitted the development of both the circulatory and the nervous systems.
The oceans are a fine source of omega 3 fatty acids and the seed-bearing plants on land are a good source of short-chain omega 6 fatty acids. Brains require close to a one to one ratio of omega 3 to omega 6 fatty acids. No animal can convert one to the other. Therefore, the great source for this one to one ratio is the seashore. Crawford and Marsh contend that this is where we developed.
The forests and savannas where many paleontologists believe that our ancestors developed have a dearth of omega 3 fatty acids and the chimpanzees who are our closest relatives never increased their brain size as their body size increased. Without exception all the large mammals from the forests and savannas have much smaller brains in relation to their body sizes than we do. They were able to find sufficient protein and other nutrients in order to increase in size but not enough of the omega 3 fatty acids for their brains to keep pace.
The only large mammal that comes anywhere close to us in brain to body size is the dolphin. In addition to the proper ratio between the two families of fatty acids, brains need the long-chain versions, including arachidonic acid (omega 6) and docosohexanoic acid (omega 3). Lengthening the chains and making the acids more unsaturated requires particular enzymes that may be in short supply, causing another bottleneck in the development of the brain. Crawford and Marsh contend that the seashore was an ideal habitat for our ancestors to find all the necessary nutrients to develop and increase simultaneously in both brain and body size. Due to the disrupting forces of water and tides their skeletons would not have remained intact for us to discover. Actually, discoveries have often been made near bodies of water. Perhaps our ancestors were the aquatic apes.
In their recent book1 two eminent scientists, Jack Cohen and Ian Stewart, endorse The Driving Force for providing us with a "substantial and well-presented setting for human evolution, getting brains on the seashore. Seafood means success." Following are more quotations from Cohen and Stewart:
1Cohen, Jack, and Ian Stewart,The Collapse of Chaos, Discovering Simplicity in a Complex World, Penguin Books, 1995. Jack Cohen is "an internationally known reproductive biologist and Ian Stewart is "a leading British mathematician. . . . They have worked together for years to uncover the unifying features of their apparently very different branches of science."
2Crawford, Michael, and David Marsh, The Driving Force: Food, Evolution, and the Future, Harper & Row, 1989. We reviewed this book in the Fall 1991 issue of NOHA News. Professor Crawford is Director of the Institute of Brain Chemistry and Human Nutrition, Queen Elizabeth Hospital for Children, London, United Kingdom. Often in his writings Professor Crawford has pointed out that both in animal studies and with impoverished children, when the essential nutrients for the brain are inadequate, intelligence is reduced. Thus, depending on nutrient levels, even over one generation, brains can actually shrink and function more poorly, just as surely as brains can improve.
Article from NOHA NEWS, Vol. XX, No. 3, Summer 1995, pages 5-6.