The Age of Experience

David Bainbridge (Middle Age: A natural History)2012

Middle and even old age is a controlled and even pre-programmed process – a process not of decline but of development. Development -- and the genetic processes which direct it – does not stop when we reach mid-twenties. It continues well into adulthood. The tightly choreographed transition into middle age is a later, but equally important, stage of human development when we are each recast into yet another novel form.

That form is one of the most remarkable of all. It is an evolutionary novelty unique to humans – a resilient, healthy, energy-efficient and productive phase of life which has laid the foundations for our species’ success. Indeed the multiple roles of older people in human societies are so complex and intertwined, that it could be argued they are the most impressive living things yet produced by natural selection.

There is evidence that many hunter-gatherers have taken decades to learn their craft and resource-acquiring abilities may not peak till they are over 40 years of age. Thus, middle-aged people may be seen as an essential human innovation, an elite caste of skilled, experienced ‘super-providers’ on which the rest of us depend. Modern middle age is in fact the result of millennia of natural selection.

The other key role of middle age is the propagation of information. All animals inherit a great deal of information in their genes; some also learn more as they grow up. Humans have taken this second form of information transfer to a new level. We are born knowing and being able to do almost nothing. Each of us depends on a continuous infusion of skills, knowledge and customs – collectively known as culture – if we are to survive. The main route by which culture is transferred is by middle aged people telling and showing their children what to do, as well as the young adults with whom they associate.

These two roles of middle aged humans – as super-providers and master-culture-conveyers – continue today. In offices, on construction sites and in sport around the world, we see middle aged people advising and guiding younger adults. Middle aged people can do more, earn more, in short they run the world!

All this has left its mark on the human brain. Changes do occur in thinking abilities but these are subtle and as might be expected of people propagating complex skills, middle-aged people exhibit no dramatic cognitive deterioration. In fact they tend to be better at developing long-term plans, selecting relevant material from a mass of information, planning their time and coordinating the efforts of others – a constellation of skills that we might call wisdom!

To carry out their roles in society, middle-aged people need not necessarily think better or worse than younger adults, but they do think differently. Functional brain imaging studies suggest that sometimes they use different brain regions than young people when performing the same tasks, indicating that the nature of thought itself changes as we get older.

A central and related feature of middle age is the many healthy years we enjoy after we have stopped reproducing. Female humans are unusual animals because they become infertile halfway through their lives and males often effectively ‘self-sterilise’ by remaining with their partners. Almost no other species does this.

Thus, humans can be seen as members of an elite club of species in which adulthood has become so long and complicated that it can no longer all be given over to breeding. The menopause now appears to be a coordinated, controlled process. Recent scientific research is now revealing the truth about this long-neglected phase of human life and all the evidence suggests that it is not a meandering, stumbling deterioration but a neatly executed event which is a key part of the developmental programme of middle age. Without the evolution of middle age, human life as we know it could never have existed!