The seven-year switch

TEXT Denise Peikert

Allegedly each one of us becomes a new person every seven years: our figures change, as do our hair and personality. How true is this?

The seven-year rule cites a convenient interval that seems to fit everything we are discussing: the second dentition when children start school; the desire for offspring around the age of 28; and the fact that, at 35, you suddenly feel much older than a few days earlier. Every seven years, people like to claim, the body changes; some even say it morphs completely, as does one’s hair. The subject is a great source of small talk: innocuous yet plausible. One where you can always ask yourself: is this just a myth, or is it based on science?

Let’s begin with the myth. Through the annals of human history, the number seven has always held a special fascination. Those annals obviously include the ancient Greeks. Shortly after the birth of Christ, when the philosopher Philo of Alexandria was opining about life in general, his quest for a structure led him to posit seven-year periods. To paraphrase the philosopher: the first septennial marked tooth replacement, the second puberty, the third – in men – the growth of facial hair, and the fourth marriage; these were followed by intellectual maturity and the equanimity of old age. “Yet in the tenth septennial,” the philosopher wrote, “it is best to die. At any age beyond that, human beings become frail and useless.” While that last hypothesis is no longer true, the basic idea has survived to this day. Why? Because of Rudolf Steiner. When first postulating his anthroposophical world view in the early 20th century, he too approached life through septennials. However, he was less concerned with baby teeth and beard growth and more interested in the evolution of the human psyche and character. Until then, the seven-year theory was just that: a theory seeking to identify general rules that govern a human lifetime. This has most strongly influenced today’s Waldorf philosophy based on Rudolf Steiner. It defines an individual’s evolution from birth to second dentition, from there to puberty, and from there to maturity. That said, modern Waldorf educators tend to reject a strict septennial dogma. And now to the medical aspect. If you want to know more about the scientific side of the septennial, you can contact Henning Elsner, Chief Physician at the Lahnhöhne Hospital in Lahnstein, which specializes in psychosomatic afflictions. Elsner worked as an internist for many years while adhering to the orthodox school of medicine. Yet, he says, he had always had the feeling that physical ailments were closely related to psychological problems. Today Elsner works largely in the field of psychotherapy – and recognizes the septennial rhythm in many of his patients’ biographies. “Certain vital issues simply affect people more during a certain phase of their lives,” he says. In other words, if something unexpected happens around a person’s twenty-first birthday, that could sometimes be the reason behind later struggles with depression and anxiety. “With patients who come to me years later, I often realize that they initially suffered from depression long ago,” says Elsner. He specifically addresses the septennial cycle, asking his patients to respond to questions about phases of their lives. What happened in your first seven years? Do you recall your first sensory experience? Your first teddy bear? Elsner regards this as a therapeutic reconnection with a person’s own life story. The septennials serve here as a compass of sorts, a navigation aid for both therapists and patients that provides signposts through the course of a person’s life. “Quite simply, there are challenges that belong in certain stages – if people realize that, they often experience it as a relief,” Elner has found.

That said, anthroposophy is based on assumptions and observations; it can only offer cautious impulses for people to reflect on their lives. Being a philosophy, it is immune to the test of medical proof. Steiner, the founder of the anthroposophical world view, nonetheless ventured into scientific waters. He wrote that, over a period of seven to eight years, human beings rejected their physical material and renewed it.

Last but not least, it is time to address the work of the stem-cell and molecular biologist Jonas Frisén, who teaches at the Karolinska Institute in Stockholm, one of Europe’s most highly respected medical schools. He says he

has done a bit of “amateur research” on the seven-year myth. His research has shown that human beings actually do undergo a complete physical renewal every seven to ten years – but the process proceeds faster in the brain than in the skin. Frisén’s findings on exactly what takes place created a sensation in 2005: he computed the amount of time it took for each part of the body to be rejuvenated or replaced in full. Accordingly, it takes only two to four days for the walls of the small intestine to be renewed; the air sacs in our lungs need eight days. In contrast, fat cells have a lifetime of eight years, and our skeletons need about a decade to morph.

As precise as these findings may seem, the mysteries remain. Take the heart, for instance, one of the hardest-working body parts. In his more recent studies from 2015, Frisén found that a young adult’s heart produces a maximum of one percent of new cells every year, the elderly only up to half a percent. And even those who live long lives will never have a new heart: at most, 40 percent of the various cells in this organ are replaced during a lifetime. And this takes us back to the science of the myth: even if a human being changes inside and out in the course of life’s different phases, he or she will ultimately remain the same person.

Denise Peikert works as a journalist in Leipzig and writes for media such as MDR television and Die ZEIT and Frankfurter Allgemeine Sonntagszeitung newspapers. She spends her time at her desk poring over clinical studies and bills of indictment. Outdoors she is more likely to be conducting interviews in cowsheds and circus rings.