A few weeks ago, I pulled up the post I wrote in November 2016 about leaving behind the seven-year life cycle model. It is the most-read thing I have ever published on this site. I read it slowly, the way you re-read something you wrote when you were a slightly different person. And I kept asking myself: was I right?
I was 46 when I wrote that post. I am 55 now. I have watched people move through the Blobs framework during that time, tested it against my own life, and heard from readers who recognised their experience in the six-year stages I proposed. I have also lived through a global pandemic that reshaped how people think about time, age, and what matters. So this is not a victory lap. It is an honest look at what held up, what surprised me, and what I still cannot prove.
What the science has confirmed
The argument that started my original post, the claim that the body renews all its cells every seven years, remains thoroughly debunked. If anything, the science has gotten clearer. The myth has been traced back to a 2005 carbon dating study that estimated the average age of human cells at seven to ten years. Journalists and wellness writers turned that average into a claim about total renewal. It was never true. Your gut lining replaces itself in days. Your skeleton takes about ten years. Your heart renews only 40 percent of its muscle cells across an entire lifetime. Neurons in your cerebral cortex are with you from birth until death.
There is no biological seven-year clock. There never was.
What surprised me more was discovering that even Rudolf Steiner, whose seven-year stages underpin the entire Waldorf education system, was more cautious than his followers. In one set of lectures, Steiner said plainly that you cannot expect children to develop in exact seven-year rhythms, that there are “too many accelerations and delays.” He spoke of developmental steps happening “around” the sixth or seventh year, not at fixed points. His own language was open and approximate. It was later interpreters who turned his sketches into a rigid system.
The German psychologist Fritz Beckmannshagen put it bluntly in his critical study of Waldorf schools: the expert in developmental psychology stands astonished before this sparse model and wonders how a respected school system has operated on it for decades, unconcerned about the progress of science. That was written in 1984. Forty years later, the same critique applies.
What the Blobs model got right
The six-year model I proposed was never meant to be biologically precise. There is no six-year cell cycle, either. What I argued in 2016 was that six-year stages map more honestly onto the way we actually live now.
That argument has aged well. Schooling begins at 5 or 6 in most countries, not 7. Puberty and the teenage years are widely understood as the 13 to 18 period, not 14 to 21. The concept of “emerging adulthood,” the years between 19 and 24 when people are no longer adolescents but not yet independent adults, has become one of the most studied ideas in developmental psychology over the past decade. It fits the Blobs framework precisely. It does not fit the seven-year model at all.
The biggest confirmation came from an unexpected direction. When I looked at how different cultures mark life transitions, I found that the most enduring frameworks do not use seven-year intervals. Confucius described life in stages anchored to the decades: standing firm at 30, having no doubts at 40, knowing the will of Heaven at 50. The Hindu ashrama system divides life into four broad phases, not seven-year slices. The pattern I see across cultures is that real transitions cluster around every five to seven years, with six being a useful central point.
Where the framework still has open questions
I will be honest. The Blobs model does not have peer-reviewed studies behind it. No longitudinal data set has tested whether six-year stages predict life outcomes better than seven-year ones, or five-year ones, or no stages at all. The scientific literature on life stages tends to work with broader categories: childhood, adolescence, emerging adulthood, midlife, late life. Specific numerical boundaries are always somewhat arbitrary.
I also cannot claim that six years works the same way across every culture. The life milestones that anchor the Blobs, schooling at 6, independence at 24, career peak around 50, are products of a particular kind of society. In places where children start working at 10 or marry at 16, the boundaries shift. The model describes something real, but it describes it best for people living in urbanised, post-industrial societies. I want to be transparent about that.
What I believe now
I believe more strongly than I did in 2016 that the seven-year model has outlived its usefulness. The science does not support it. The cultural traditions that inspired it were built for lifespans that ended at 50 or 60. The modern world moves in shorter, faster rhythms, and the old model cannot keep pace.
I also believe that life stages matter. Not because they predict your future, but because they give you a way to understand where you are. Knowing that your restlessness at 50 is the opening of Autumn, or that your confusion at 27 is a normal part of the first Blob of Summer, does not solve anything. But it makes you feel less alone.
That is what the Blobs model has taught me that the seven-year model never could. Not a rule. A mirror.
One question for you
When you look at the major transitions in your own life, do they cluster around every six years, every seven, or at intervals that follow no pattern at all?
Life Stages in Six-Year Blobs – Personal Growth by Age 
Any Comments?