Scientists have been debating why and how the human brain started outgrowing the brains of other mammals, starting about two million years ago.
The human brain is built from fatty acids, and omega-3 DHA, which is essential to brain cell structure and to thinking and memory, constitutes about 60 percent of the fatty acids in our brains.
Humans can convert plant source omega-3s into DHA, but do so very inefficiently. The only foods naturally rich in omega-3 DHA are fish, shellfish, algae, and animals that eat heavily aquatic diets (amphibians, crocodiles, hippos, etc.).
Accordingly, some researchers – led by renowned British brain researcher Michael Crawford, Ph.D. – have suggested that our immediate evolutionary ancestors must have eaten diets rich in DHA.
(Paleoanthropologists refer to humans and human ancestors as members of the “hominin” family: a category that encompasses all of the Homo species – including Homo sapiens – the Australopithecines, and other ancient ancestors.)
But other scientists have complained about a lack of evidence for the “DHA theory” of brain evolution.
To date, most paleoanthropologists still hew to the traditional “savannah theory”, which posits that pre-humans evolved into big-brained humans on diets consisting of green plants, nuts, seeds, roots, and small land animals.
Brain expert’s evolutionary theory accrues evidence
Dr. Crawford’s hypothesis gained important support three years ago, when a team led by Arizona State University researchers published evidence of early humans living on the South African coast about 164,000 years ago.
That date was far earlier than any ever documented for shore-dwelling humans, and sits smack in the center of the time period when anatomically modern humans emerged. (See “Omega-3 Brain Evolution Theory Gets ...
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