Paleo diet: Big brains needed carbs

Related Articles

Related Articles

Understanding how and why we evolved such large brains is one of the most puzzling issues in the study of human evolution.

It is widely accepted that brain size increase is partly linked to changes in diet over the last 3 million years, and increases in meat consumption and the development of cooking have received particular attention from the scientific community.

Dr. Karen Hardy and her team bring together archaeological, anthropological, genetic, physiological and anatomical data to argue that carbohydrate consumption, particularly in the form of starch, was critical for the accelerated expansion of the human brain over the last million years, and coevolved both with copy number variation of the salivary amylase genes and controlled fire use for cooking.

 

With global increase in obesity and diet-related metabolic diseases, interest has intensified in ancestral or ‘Palaeolithic’ diets, not least because – to a first order of approximation – human physiology should be optimized for the nutritional profiles we have experienced during our evolution. Up until now, there has been a heavy focus on the role of animal protein and cooking in the development of the human brain over the last 2 million years, and the importance of carbohydrate, particular in form of starch-rich plant foods, has been largely overlooked.

Hardy’s team highlights the following observations to build a case for dietary carbohydrate being essential for the evolution of modern big-brained humans:

(1) The human brain uses up to 25% of the body’s energy budget and up to 60% of blood glucose. While synthesis of glucose from other sources is possible, it is not the most efficient way, and these high glucose demands are unlikely to have been met on a low carbohydrate diet;

(2) Human pregnancy and lactation place additional demands on the body’s glucose budget and low maternal blood glucose levels compromise the health of both the mother and her offspring;

(3) Starches would have been readily available to ancestral human populations in the form of tubers, as well as in seeds and some fruits and nuts;

(4) While raw starches are often only poorly digested in humans, when cooked they lose their crystalline structure and become far more easily digested;

(5) Salivary amylase genes are usually present in many copies (average ~6) in humans, but in only 2 copies in other primates. This increases the amount of salivary amylase produced and so increases the ability to digest starch. The exact date when salivary amylase genes multiplied remains uncertain, but genetic evidence suggests it was at some point in the last 1 million years.

Hardy proposes that after cooking became widespread, the co-evolution of cooking and higher copy number of the salivary amylase (and possibly pancreatic amylase) genes increased the availability of pre-formed dietary glucose to the brain and fetus, which in turn, permitted the acceleration in brain size increase which occurred from around 800,000 years ago onwards.

Eating meat may have kick-started the evolution of bigger brains, but cooked starchy foods together with more salivary amylase genes made us smarter still.

Read the study published in The Quarterly Review of Biology, http://www.jstor.org/stable/10.1086/682587

PRESS RELEASE – UNIVERSITY OF CHICAGO PRESS JOURNALS

Download the HeritageDaily mobile application on iOS and Android

More on this topic

LATEST NEWS

Photos of Stolen Mosaic Reveals Oldest Representation of Roman Hydraulic Wheel

Researchers from the University of Warsaw have determined that a mosaic stolen from Apamea in present-day Syria is the oldest representation of a Roman hydraulic water wheel.

Study Reveals True Origin of Oldest Evidence of Animals

Two teams of scientists have resolved a longstanding controversy surrounding the origins of complex life on Earth.

The Microbiome of Da Vinci’s Drawings

The work of Leonardo Da Vinci is an invaluable heritage of the 15th century. From engineering to anatomy, the master paved the way for many scientific disciplines.

The Private Estates of the Royal Family

The private estates of the Royal Family are the privately owned assets, not to be confused with the Crown Estates which belong to the British monarch as a corporation sole or "the sovereign's public estate".

Field Geology at Mars’ Equator Points to Ancient Megaflood

Floods of unimaginable magnitude once washed through Gale Crater on Mars' equator around 4 billion years ago - a finding that hints at the possibility that life may have existed there, according to data collected by NASA's Curiosity rover and analyzed in joint project by scientists from Jackson State University, Cornell University, the Jet Propulsion Laboratory and the University of Hawaii.

Middle Stone Age Populations Repeatedly Occupied West African Coast

Although coastlines have widely been proposed as potential corridors of past migration, the occupation of Africa's tropical coasts during the Stone Age is poorly known, particularly in contrast to the temperate coasts of northern and southern Africa.

Naqa – The Meroitic City

Naqa, also called Naga'a, and presently referred to as the El-Moswarat Andel-Naqa'a Archaeological Area was one of the ancient cities of the Nubian Kingdom of Kush, located on the east-bank of the River Nile in Western Butan (historically called the Island of Meroë) in Sudan.

Prehistoric Shark Hid its Largest Teeth

Some, if not all, early sharks that lived 300 to 400 million years ago not only dropped their lower jaws downward but rotated them outwards when opening their mouths.

Popular stories

Legio IX Hispana – The Lost Roman Legion

One of the most debated mysteries from the Roman period involves the disappearance of the Legio IX Hispana, a legion of the Imperial Roman Army that supposedly vanished sometime after AD 120.

The Secret Hellfire Club and the Hellfire Caves

The Hellfire Club was an exclusive membership-based organisation for high-society rakes, that was first founded in London in 1718, by Philip, Duke of Wharton, and several of society's elites.

Port Royal – The Sodom of the New World

Port Royal, originally named Cagway was an English harbour town and base of operations for buccaneers and privateers (pirates) until the great earthquake of 1692.

Matthew Hopkins – The Real Witch-Hunter

Matthew Hopkins was an infamous witch-hunter during the 17th century, who published “The Discovery of Witches” in 1647, and whose witch-hunting methods were applied during the notorious Salem Witch Trials in colonial Massachusetts.