The adage “like a kid at heart” may be truer than we think, since new research is showing that grown-ups are more immature than ever. Specifically, it seems a growing number of people are retaining the behaviors and attitudes associated with youth. As a consequence, many older people simply never achieve mental adulthood, according to a leading expert on evolutionary psychiatry. Among scientists, the phenomenon is called psychological neoteny.

The theory’s creator is Bruce Charlton, a professor in the School of Biology at the University of Newcastle upon Tyne, England. Charlton explained that humans have an inherent attraction to physical youth, since it can be a sign of fertility, health and vitality. In the mid-20th century, however, another force kicked in, due to increasing need for individuals to change jobs, learn new skills, move to new places and make new friends. A child-like flexibility of attitudes, behaviors and knowledge is probably adaptive to the increased instability of the modern world. Formal education now extends well past physical maturity, leaving students with minds that are, he said, “unfinished”. When formal education continues into the early twenties, it probably, to an extent, counteracts the attainment of psychological maturity, which would otherwise occur at about this age.

Charlton pointed out the past cultures often marked the advent of adulthood with initiation ceremonies. While the human mind responds to new information over the course of any individual’s lifetime, Charlton argues that past physical environments were more stable and allowed for a state of psychological maturity. In hunter-gatherer societies, that maturity was probably achieved during a person’s late teens or early twenties. By contrast, many modern adults fail to attain this maturity, and such failure is common and indeed characteristic of highly educated and, on the whole, effective and socially valuable people. People such as academics, teachers, scientists and many other professionals are often strikingly immature outside of their strictly specialist competence in the sense of being unpredictable, unbalanced in priorities, and tending to overreact.

Charlton added that since modern cultures now favor cognitive flexibility, “immature” people tend to thrive and succeed, and have set the tone not only for contemporary life, but also for the future, when it is possible our genes may even change as a result of the psychological shift. The faults of youth are retained along with the virtues, he believes. These include short attention span, sensation and novelty-seeking, short cycles of arbitrary fashion and a sense of cultural shallowness. At least youthfulness is no longer restricted to youth, he said, due to overall improvements in food and healthcare, along with cosmetic technologies.

David Brooks, a social commentator and a columnist at The New York Times, has documented a somewhat related phenomenon concerning the current blurring of the bourgeois world of capitalism and the bohemian counterculture, which Charlton believes is a version of psychological neoteny. Brooks believes such individuals have lost the wisdom and maturity of their bourgeois predecessors due to more emphasis placed on expertise, flexibility and vitality.

The first paragraph mainly conveys the message that________.