One of the issues that concern many people, is whether it is true that our body is renewed every seven years. It is believed that this could happen in ten years, and we become completely new people.
This is due to the fact that our cells are updated and replaced with new ones. This explains the fact that sometimes we suddenly feel a decade younger.
Individual cells have a final life and death, only to be replaced by new cells. The human body has about seventy trillion cells.
Each cell type has its own life, and when a person dies, the time it takes for all the cells of the body to die may be from several hours to overnight.
Investigators often use this fact to determine the cause, and time of death of a murder victim.
Red blood cells live about four months, and white blood cells live an average of a year. Skin cells live about three weeks, and intestinal cells die after four days.
Sperm lifespan is about three days, brain cells live as long as the person themself - neurons in the cortex are not updated after they die.
So, a seven-year cycle is not something special, because cells are continually updated after old cells die, in different parts of the body.
Actually this is not just a myth or a mistake, because summation of the life of all cells in the human body, will give a figure close to seven years.