According to scientific research, our human lives function on cycles lasting seven years:

- A new study determines that most people shed about half their friends every seven years and replace them with new ones;

- And commonly-held knowledge tells us that the human body’s cells all regenerate themselves every seven years, which follows that we become all become a “new person” periodically.

So we acquire a new social circle to pair with our new bodily shell. Of course, that cellular-regrowth thing turns out to be mostly nonsense. So I’ll assume the same of the corresponding seven-year social-network churn.