Wilderness Underfoot: The human brain — do we owe it all to the fish?

StoryImage( ‘/Images/Story//Auto-img-117692435930277.jpg’, ”, ‘The adage that fish is “brain food” may have some truth to it – Fish consumption may have caused rapid brain growth in our hominid ancestors. Fish are a rich source of the polyunsaturated fatty acid known as “docosahexaenoic acid” (DHA). They’re also rich in iodine and iron. These nutrients are vital to the brain, and when they’re missing from our diet, it can lead to dementia and diminished brain functioning.‘);

The human brain is a hungry organ that may have gained its evolutionary boost when early humans began foraging at the water’s edge.

Inquisitive scientists, philosophers, sociologists and psychologists have long marveled at the human brain, wondering how our cognitive abilities could have advanced so far beyond the earth’s other creatures.

Researchers have often theorized that advanced skills, such as language and toolmaking in our hominid ancestors, required, and thereby caused, the brain to grow larger and more complex. Many believed that because natural selection favored smarter hominids, the trend toward bigger, more powerful brains simply continued until Homo sapiens (humans) surpassed other hominids.

But new research is challenging established ideas about the evolution of the human brain. At the forefront of the debate is Stephen Cunnane, a metabolic physiologist at the University of Sherbrooke in Quebec. Cunnane and his associates argue that evolutionary pressures alone weren’t enough to cause such a sudden and dramatic change. Bigger brains, they say, would have required a dependable supply of just the right food, rich in the kinds of fats and nutrients that the hominid brain craves most of all.

In nature, smarts don’t come cheaply. Every evolved feature has a price, and nothing is as expensive as a big, powerful brain. It demands a huge supply of nutrients and energy to form, to grow, and to stay alive. Those nutrients were found at the water’s edge, in shorebird eggs, clams and mussels, frogs, and most of all, fish.

Lest we become too full of our own cleverness, it appears a key factor to our domination in the brain game was dumb luck. Our ancestors—having first evolved to eke out their lives on the savannah with a seasonal diet that might change wildly from one month to the next—stumbled into a rich source of brain food when they took to the water’s edge. There, they found a year-round source of nutrients, including the same healthy Omega-3 fatty acids that are making news today.

The fishy diet allowed early humans one adaptation in particular that was not found in other primates: being born with excess body fat. Body fat is vital for nourishing a newborn baby’s rapidly growing brain, which consumes 75 percent of the baby’s daily energy intake. Early human mothers derived this energy from the shoreline diet, ensuring their brainy children would have plenty of nourishment, both in the womb and during breast-feeding.

from the April 18-24, 2007, issue

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