Paleo is all the rage today but is it the way our ancestors really ate? An interesting new study has shown that Paleolithic humans would not have evolved if they were following today’s version of the diet.
“Starchy carbohydrates were a major factor in the evolution of the human brain, according to a new study co-authored by researchers from the University of Sydney’s Charles Perkins Centre and Faculty of Agriculture and Environment. Cooking starchy food was central to the dietary change that triggered and sustained the growth of the human brain.”
It has long been hypothesized that protein was responsible for the increase in the size of the human brain. This latest research challenged this theory however.
“Global increases in obesity and diet-related metabolic diseases have led to enormous interest in ancestral or Palaeolithic’ diets,” said Professor Jennie Brand-Miller.
Up until now, there has been a heavy focus on the role of animal protein in the development of the human brain over the last two million years. The importance of carbohydrate, particularly in the form of starch-rich plant foods, has been largely overlooked. Our research suggests that dietary carbohydrates, along with meat, were essential for the evolution of modern big-brained humans.
“The evidence suggests that Palaeolithic humans would not have evolved on today’s ‘Paleo’ diet.”
The development of the modern human brain required relatively large amounts of glucose. A low carbohydrate diet would not have provided enough glucose to explain the changes we have seen.
The human brain uses up to 25 per cent of the body’s energy budget and up to 60 per cent of blood glucose. Human pregnancy and lactation, in particular, place additional demands on the body’s glucose budget, along with increased body size and the need for mobility and dietary flexibility.
Many paleo followers believe that starchy foods were not consumed or were not available back then. Of course, this is not at all the case. Starchy foods would have been a readily available source of energy to supplement their meat with.
Starches would have been readily available to early human populations in the form of tubers, seeds and some fruits and nuts. But it was only with the advent of cooking that such foods became more easily digested, leading to “transformational” changes in human evolution, said co-author Professor Les Copeland.
Researchers also point to evidence in salivary amylase genes, which increase the amount of salivary enzymes produced to digest starch. While modern humans have on average six copies of salivary amylase genes, other primates have only an average of two. The exact point at which salivary amylase genes multiplied is uncertain, but genetic evidence suggests it occurred in the last million years, around the same time that cooking became a common practice.
“After cooking became widespread, starch digestion advanced and became the source of preformed dietary glucose that permitted the acceleration in brain size,” Professor Copeland said.
So whilst meat and protein would have played an important role in evolution, it would not be enough for us to get to where we are today without starchy foods.
“We believe that while meat was important, brain growth is less likely to have happened without the energy obtained from carbohydrates. While cooking has also been proposed as contributing to early brain development, cooking carbohydrates only makes sense if the body has the enzymic equipment to process these.”
According to the researchers, a diet similar to that which gave us our large brains in the Palaeolithic era would be positive for human health. However, unlike the modern Paleo diet, that diet should include underground starchy foods such as potatoes, taro, yams and sweet potatoes, as well as more recently introduced starchy grains like wheat, rye, barley, corn, oats, quinoa and millet.
