SUNDAY TIMES, 31ST July 2011
The Sunday Times 31st July 2011 front page has it that people at Cambridge University claim the brain human brain has reached the limit of intelligence! Two reasons are given. (i) miniaturization of brain cells (ii) The human brain accounts for 2% of the body weight but uses 20% of the energy "the requirements are sufficiently demanding to limit our performance.." It is good that they have raised this issue as for too long we have neglected the brain and its requirements for growth.
However, they talk about evolution. I recommend they read scientific papers by ourselves and others encapsulated in 2 books (The Driving Force Crawford and Marsh, Harper and Rowe (USA), 1989 and “Environmental Influences on Human Brain Evolution “– eds Kathy Stewart & Stephen Cunnane Wiley-VCH2010) describing the significance of docosahexaenoic acid (DHA) as a power in cerebral expansion. DHA is known to be vital for the structure and function of the photoreceptor, synapse and neuron, it stimulates neurogenesis and neurite outgrowth, activates a nuclear receptor and is known to stimulate over 100 genes in the brain for energy use and development. In a study of 42 species, we found the chemistry of ther brains wrt DHA etc was identical. The difference was size which was dependent on the availability of DHA. Moreover the FAO-WHO 2011 report on dietary fats (nutrition report no 91) gives the evidence on its essentiality for infant vision and cognition the highest evidence-based credibility. The rich food supply of DHA in the ecological niche of our origin amply fueled epigenetic cerebral expansion as we increased in body size. Vision and the brain evolved in the sea 500-600 million years ago using DHA. It has been conserved in this role ever since. By turning our backs on the marine food web over the last two centuries and with abuse of the marine food web especially with pollution of the rivers and estuaries and coast lines, we have posed a threat to the sustainability of the brain and intelligence. The sign of this is the rise in brain disorders that now have overtaken all other burdens of ill health. For the EU 25 member states the cost in 2004 was 386 billion Euros. In the UK the DoH estimated the cost in 2007 of mental ill health to have risen to £77 billion : a cost greater than heart disease and cancer combined. It is now significantly greater.
As regard their second point on inadequate energy to fuel the brain. With only 2% of body as brain we have a smaller brain than a squirrel which has 2.3% and manages very well. I am also surprised they seem to have missed the fact that we have an epidemic obesity from the high energy dense foods we eat today and over consumption! It is however, excellent that they have opened this debate.