General, Research, Technology

The human body is completely renewed every seven years.

Know yourself; love yourself; be honest with yourself. For many years, these old truths have been sung by artists, musicians and philosophers, from Jean-Paul Sartre to Bob Dylan. But how to know yourself if you are constantly changing? The human body is in constant motion: it loses and grows skin, renews the lungs, grows new hair.


According to scientists, the body replaces itself with a completely new set of cells every seven to ten years, and some of our most important parts of the body are updated even faster.

Some of you might think: "Well, that explains why my wife / brother / father behaves like little children." Others may think that new cells may be the key to long life. Unfortunately, everything is much more complicated.

Body rejuvenation

In the early 50s, scientists discovered the powerbody rejuvenation due to - seriously - the introduction of radioactive atoms into objects and observation of their movements. They found that on average 98% of the atoms in the body - the small particles of matter that form the molecules and cells of the body - are replaced every year. Most new atoms are taken in with the air we breathe, the food we eat, and the liquid we drink.

Fifty years later, the Swedish molecular biologistJonas Friesen studied body tissue renewal by measuring the level of radioactive material - carbon-14. This material was thrown into the air before surface tests of nuclear weapons were banned in 1963. Carbon-14 is inhaled by plants that humans and animals eat day after day, and is part of our DNA. But unlike other atoms and molecules that are constantly changing, human DNA remains unchanged from the moment the cell is born - which occurs when the parent cells divide - until the end of its life. When a cell divides, in other words, DNA, which is introduced into new cells, contains a certain level of carbon-14, which corresponds to the level of this substance in the air around us at that moment. Thus, this substance can be considered a kind of time stamp by which scientists can determine when the cell was created.

Friesen found that body cells are mostlyparts replace themselves every 7-10 years. In other words, old cells die and are replaced by new ones during this period of time. The process of cell renewal is faster in some parts of the body, but complete rejuvenation from the toes to the head takes about ten years.

This explains why the flakes of our skinfall off, nails grow, and hair falls out. But if we are constantly replenished with new cells, why does the body age? Shouldn't new cells act like a Botox shot? When it comes to aging, it turns out that its secret lies not in our cells, but in cellular DNA.

Cell life span

The body is updated by various methods. The working time of cells in certain parts of the body depends on what is required of them. Red blood cells, for example, live for four months, since they are required to go through a difficult path through the circulatory system and deliver oxygen to the tissues of the whole body.

But how many other cells live.

  • Skin: the epidermis undergoes a fair amount of wear, since it acts as an external protective layer of the body. These skin cells are updated every two to four weeks.
  • Hair: The body's natural hairline has a lifespan of about 6 years for women and 3 years for men.
  • Liver: The liver cleanses the human body by removing a wide range of pollutants from our systems. It contributes to a constant blood supply and remains immune to damage from these pollutants and toxins, renewing its cells every 150-500 days.
  • Stomach and intestines: the cells lining the surface of the stomach and intestines live a short and complex life. Constantly exposed to caustic stomach acids, they usually live only 5 days, no more.
  • Bones: cells of the skeletal system regenerate almost constantly, but the whole process takes up to 10 years. The renewal process slows down as we age, so our bones become thinner.

Despite all this constant regeneration, peoplewho want to live forever, should not stop searching for the source of youth. The fact is that we continue to age and gradually die. Friesen and others believe that this may be due to DNA mutations that worsen, moving to new cells over time.

There are also a number of cells that neverleave us and can contribute to the aging process, or at least the decay of the body over time. Although the cornea of ​​the eye can be restored in just one day, the lens and other areas of the eye do not change. The same thing happens with neurons in the cerebral cortex - the outer layer of the brain that is responsible for memory, thinking, language, attention and consciousness - they remain with us from birth to death. Since they are not replaced, the loss of these cells leads to serious ailments. There is good news: other areas of the brain, the olfactory bulb, which is responsible for the smell, and the hippocampus, which is responsible for learning, can and are updated.

Take care of yourself. The first person has already been born who will live forever.