Earth Science News  





. Love That Baby Fat

Human brains aren't just comparatively big, they're hungry. The average newborn's brain consumes an amazing 75-per cent of an infant's daily energy needs. According to Dr. Cunnane, to fuel this neural demand, human babies are born with a built-in energy reservoir that cute baby fat.
by Staff Writers
Sherbrooke, Quebec (SPX) Feb 22, 2006
Forget the textbook story about tool use and language sparking the dramatic evolutionary growth of the human brain. Instead, imagine ancient hominid children chasing frogs. Not for fun, but for food. According to Dr. Stephen Cunnane it was a rich and secure shore-based diet that fuelled and provided the essential nutrients to make our brains what they are today.

Controversially, according to Dr. Cunnane our initial brain boost didn't happen by adaptation, but by exaptation, or chance.

"Anthropologists and evolutionary biologists usually point to things like the rise of language and tool making to explain the massive expansion of early hominid brains. But this is a Catch-22. Something had to start the process of brain expansion and I think it was early humans eating clams, frogs, bird eggs and fish from shoreline environments. This is what created the necessary physiological conditions for explosive brain growth," says Dr. Cunnane, a metabolic physiologist at the University of Sherbrooke in Sherbrooke, Quebec.

The evolutionary growth in hominid brain size remains a mystery and a major point of contention among anthropologists. Our brains weigh roughly twice as much as our similarly sized earliest human relative, Homo habilis two million years ago. The big question is which came first the bigger brain or the social, linguistic and tool-making skills we associate with it?

But, Dr. Cunnane argues that most anthropologists are ignorant or dismissive of the key missing link to help answer this question: the metabolic constraints that are critical for healthy human brain development today, and for its evolution.

Human brains aren't just comparatively big, they're hungry. The average newborn's brain consumes an amazing 75-per cent of an infant's daily energy needs. According to Dr. Cunnane, to fuel this neural demand, human babies are born with a built-in energy reservoir that cute baby fat. Human infants are the only primate babies born with excess fat. It accounts for about 14 per cent of their birth weight, similar to that of their brains.

It's this baby fat, says Dr. Cunnane, that provided the physiological winning conditions for hominids' evolutionary brain expansion. And how were hominid babies able to pack on the extra pounds? According to Cunnane their moms were dining on shoreline delicacies like clams and catfish.

"The shores gave us food security and higher nutrient density. My hypothesis is that to permit the brain to start to increase in size, the fittest early humans were those with the fattest infants," says Dr. Cunnane, author of the book Survival of the Fattest, published in 2005.

Unlike the prehistoric savannahs or forests, argues Dr. Cunnane, ancient shoreline environments provided a year-round, accessible and rich food supply. Such an environment was found in the wetlands and river and lake shorelines that dominated east Africa's prehistoric Rift Valley in which early humans evolved.

Dr. Cunnane points to the table scrap fossil evidence collected by his symposium co-organizer Dr. Kathy Stewart from the Canadian Museum of Nature, in Ottawa. Her study of fossil material excavated from numerous Homo habilis sites in eastern Africa revealed a bevy of chewed fish bones, particularly catfish.

More than just filling the larder, shorelines provided essential brain boosting nutrients and minerals that launched Homo sapiens brains past their primate peers, says Dr. Cunnane, the Canada Research Chair in Brain Metabolism and Aging.

Brain development and function requires ample supplies of a particular polyunsaturated fatty acid: docosahexaenoic acid (DHA). DHA is critical to proper neuron function. Human baby fat provides both an energy source for the rapidly growing infant grey matter, and also, says Dr. Cunnane, a greater concentration of DHA per pound than at any other time in life.

Aquatic foods are also rich in iodine, a key brain nutrient. Iodine is present in much lower amounts from terrestrial food sources such as mammals and plants.

It was this combination of abundant shoreline food and the "brain selective nutrients" that sparked the growth of the human brain, he says.

"Initially there wasn't selection for a larger brain," argues Dr. Cunnane. "The genetic possibility was there, but it remained silent until it was catalyzed by this shore-based diet."

Dr. Cunnane acknowledges that for the past 20 years he's been swimming upstream when it comes to convincing anthropologists of his position, especially that initial hominid brain expansion happened by chance rather than adaptation.

But, he says, the evidence of the importance of key shoreline nutrients to brain development is still with us painfully so. Iodine deficiency is the world's leading nutrient deficiency. It affects more than a 1.5 billion people, mostly in inland areas, and causes sub-optimal brain function. Iodine is legally required to be added to salt in more than 100 countries.

Says Dr. Cunnane: "We've created an artificial shore-based food supply in our salt."

Related Links
University of Sherbrooke

Melting Yukon Ice Fields Reveal Ancient Canadian Footwear
Ottawa, Canada (AFP) Feb 22, 2006
Researchers have discovered what they believe to be Canada's oldest known footwear -- a 1,400-year-old mangled leather moccasin -- in the northern Yukon territory, officials told AFP Wednesday. The ankle-high sewn leather shoe was first thought to be a hunter's bag and was kept frozen until recently when archeologists cleaned and assembled the fragile pieces.

.
Get Our Free Newsletters Via Email
  



  • Levee Modeling Study To Provide Technical Data For Rebuilding New Orleans
  • Scientists Say California Quake Could Cause Katrina II
  • US Troops Join Landslide Rescue As Buried School Is Located
  • Cornell, WCMC And LockMart To Create Plan To Manage Mass Casualties In Disasters

  • Greenland Glaciers Dumping Ice Into Atlantic At Faster Pace
  • The Arctic And Global Warming
  • Late Pleistocene Americans Faced Chaotic Climate Change Environments
  • Ancient Climate Studies Suggest Earth On Fast Track To Global Warming

  • Earth From Space: Copenhagen, Denmark
  • ALOS Captures First Image of Fujiyama
  • Southern Greenland Glaciers Dumping Ice Faster
  • NASA Satellite Technology Helps Fight Invasive Plant Species

  • Environmental Metagenomics Tapping Opportunities For Clean Energy
  • Walker's World: EU's Bold Caucasus Bid
  • Garbage Truck Industry Ponders Move To LNG
  • Nuclear Fusion On A Tabletop

  • Grants Put ANU In Bird Flu Fight Frontline
  • New Influenza Vaccine Takes Weeks To Mass Produce
  • Bird Flu Hits Western Europe
  • Bird Flue Hits Africa

  • Dragonflies Uses Drag To Carry Their Weight, Offer Insight Into Flight
  • Oceans Are 70 Percent Shark Free
  • Sexual Reproduction Delays Aging In A Mammalian Species
  • Monitoring Baleen Whales With Autonomous Underwater Vehicles

  • Fourfold Increase In British Radiation Levels After Iraq Invasion
  • Water Cut Off For 20,000 People After Latest Chinese River Toxic Spill
  • China To Step Up Environmental Protection Efforts
  • Disturbing Former Farmlands Can Rouse Old Pesticides

  • Melting Yukon Ice Fields Reveal Ancient Canadian Footwear
  • Love That Baby Fat
  • Early Human Ancestors Walked On The Wild Side
  • East Africa's Rapid Development Presents Complex Push And Pull

  • The content herein, unless otherwise known to be public domain, are Copyright 1995-2006 - SpaceDaily.AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA PortalReports are copyright European Space Agency. All NASA sourced material is public domain. Additionalcopyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement