The expected life span in the world, for now, is 71.4 years and is considered that one of the greatest achievements of mankind is extended life expectancy – the average life expectancy of our first ancestors was only between 25 and 30 years. By the 1900s, it grew between the age of 45 and 50, and during the last 100 years it has grown for more than 20 years.
Aging is among the biggest well-known risks for most illnesses in humans; this term refers specifically to humans, as well as to many animals and fungi, although some organisms can live astonishingly long, such as:
Pinus aristata, type of pine (1500 years old)
Arctica islandica, shellfish species (500 years old)
Homarus americanus, American lobster (100 years)
So far, different theories about why we age and the possible ways in which this mechanism works are presented. What is common to most theories is that this process is controlled by genes. Genes control when and whether a station will divide. Most cells can only be divided by a certain number of times, after which they are aged. Cell division leads to the creation of new, young cells, thus rejuvenating the tissues in which they are located. When a cell gets old, it loses the ability to divide and is destroyed in the genetically programmed death (apoptosis) process. If all the genetic mechanisms work well, a cell that suffered from any type of stress will (prematurely) grow old and be deprived of dividing capabilities. Since such cell can no longer perform its function normally, it will be destroyed in the programmed death process. However, in some cases, the genetic mechanism fails, and the defective cell continues to divide and develops the tumor. For this reason, we have come to the conclusion why cells age (and therefore we) and lose the possibility of dividing – because in this way, the possibility of tumor formation is reduced! The more times cells divide, the greater the chance of making a mistake in their development, and the greater the chance of tumor formation. From all of this, it is likely that, although aging is an undesirable process that limits us in many ways, its primary function is somehow paradoxical – to protect us from our own cells.