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Life on this earth seems to be calibrated in some mysterious way to the number seven. We humans operate under the cadence of a seven-day week—a cycle of activity that doesn’t even follow the cosmic timing of the stars, the sun, or the moon.


Six around one

The hexagon (a six-sided object) provides the most efficient use of space. Just ask a bee busily building its honeycomb. Mathematicians and architects insist that a hexagonal room (six walls built around a floor—the “six around one” principle) provides the most efficient ratio of perimeter to area and requires the least amount of wall material per square foot of floor space.


Biological rhythms

It seems that all life moves in seven-day rhythms. A growing number of scientists have embraced a new field of study known as chronobiology that examines repeating phenomena in living organisms. These cycles are known as biological rhythms.

Franz Halberg is widely considered the “father of chronobiology.” This tall gentleman from Romania worked at the University of Minnesota in an office crammed with bookshelves that were stacked with copies of journals and papers he produced over the years. He insisted that we humans don’t just experience circadian rhythms of approximately 24 hours; we operate under circaseptan (weekly) rhythms.



Seven-day cycles

Research has uncovered many conditions about humans that seem to rise and fall in seven-day cycles. These include heartbeat, blood pressure, body temperature, hormone levels, acid content in the blood, red blood cell count, oral temperature, female breast temperature, urine chemistry and volume, the ratio between the brain’s neurotransmitters called epinephrine and norepinephrine, and the flow of several body chemicals such as the stress-coping hormone cortisol. Even the common cold is circaseptan.

Doctors have long observed that response to a malaria infection or pneumonia crisis peaks at seven days. Chicken pox symptoms (a high fever and small red spots) usually appear almost exactly two weeks after exposure to the illness. And surgical patients tend to have an increase in swelling on the seventh and fourteenth days after their surgery.

Organ transplants face similar a crisis as the body’s immune system attacks the newly introduced foreign object.

In the blood

God knew all of this, because He created us. Perhaps that’s why He commanded, in Genesis 17:12, that baby boys were to be circumcised one week after they were born. (Some scholars still don’t realize that “on the eighth day” is the Hebrew way of saying “one week later,” because the eighth day of the Jewish week was also the first day of the following week [Leviticus 23:39]). The Hebrews used inclusive reckoning when speaking of time, just like we use inclusive reckoning when speaking of the notes of the octave. In other words, God told the Israelites to circumcise their children on the octave of the day they were born.

So why wait a week to circumcise a baby boy? Prothrombin is what causes the blood to clot, preventing endless bleeding, and doctors tell us that’s when the prothrombin is at its maximum. It’s never that high again.

The week in history

Today, we take the seven-day cycle for granted, but in ancient cultures the “week” varied in length from three to nineteen days. However, in the millennium before Christ, Israel’s seven-day week took over the then-known world. And their weekly cycle revolved around something very unique. It was the Jews—those careful keepers of God’s time—who preserved one day as a period of rest and reflection, a “Sabbath” during which they focused on spiritual matters.


Symphony players



The same is true of the weekly circaseptan rhythm. That means that if you’re working on the Sabbath, you’re breaking yourself.

Maybe that’s one of the reasons why Seventh-day Adventists—a denomination of Christian believers who observe the seventh-day Sabbath—tend to live seven to ten years longer than the average citizen. They’re simply in sync with the rhythm of life.

Custom or creation


The problem with such a social convention explanation is that it can’t explain circaseptan rhythms in algae, Dahl rats, mice, guinea pigs, honeybees, beach beetles, and face flies.


And here’s something really intriguing: While human teeth are growing, small lines or ridges form on the dental enamel about every seven days. The growing tooth might even be said to exhibit a weekly “rest” as it leaves behind a dark marker, just as trees show darker rings where their growth pauses in the winter. According to scientific researchers A. Mann, J. Monge, and M. Lampl in their book Investigation Into the Relationship Between Perikymata Counts and Crown Formation Times, these lines—30 to 40 microns apart—are called striae of Retzius. These stria are found even on the teeth of fossil hominids that lived before our modern culture existed.

Why seven?

Why should all living things have an innate seven-day cycle? I’d like to suggest a not-too-wild theory. It’s found in Exodus 20:11: “In six days the Lord made the heavens and the earth, the sea, and all that is in them, but he rested on the seventh day. Therefore the Lord blessed the Sabbath day and made it holy.”



Just as we tune our radios to receive our favorite musical broadcasts, so every living cell has embedded in its primal genetic material a resonant frequency—a clock, a beat—that puts us in sync with the universe. And that powerful, mysterious beat revolves around the number seven.


The Rhythm of Life

by Tim Crosby
From the February 2016 Signs