Since 1950 there has been a steady increase in mental ill-health across the population. At the same time, there has been a similar steady decline in IQ. There is strong evidence of 'dumbing down' right across society. If this is allowed to continue it will be the greatest threat to the sustainability of the human race, even greater than the more visible threat of climate change. The Global Mental Health Crisis is a direct result of the fact that, over time, the actual size of our brains is getting smaller. This is a historical fact but is entirely reversible with better brain nutrition. This has now reached crisis proportions. In 2023, The European Brain Council recognised that "Brain Health conditions have become a global health emergency". Back in 1972, Graham Rose wrote in the Sunday Times "Unless action is taken to care for the nutrition of the brain 'We will become a race of morons!' Authors Michael A Crawford and David E Marsh have both devoted their lives to this vital area of research. This book is their legacy. In painstaking detail, they put the case of how to reverse the Global Mental Health Crisis. With greater awareness of the problem, its cause and the solution required to make a change, their message could not be clearer. By reading this book you will not be able to say, "We didn't realise". This book may contain complex research and the result of detailed research, but the message is simple. And so is the action we all need to take. We also explain the role of the environment in the evolution of the brain, leading to early Homo sapiens with a brain capacity of over 1,600cc, and explain why it is now only 1,366 cc and mental ill-health is escalating. The concepts in this book have been fifty-one years in the making. They can't wait any longer. There is no more time. Presented with these incontrovertible facts, it does not need a rocket scientist to work out what will happen if these dumbing-down trends continue! Fortunately, solutions are available which will lead to brighter and healthier children of the future.