Eternal life is one of the ultimate dreams of mankind, and it is the earliest dream that has appeared since mankind possessed wisdom.
Yes, the world is colorful, and if there is no life, then everything has nothing to do with us. Although human beings have been pursuing eternal life since very early on, without exception, they have not succeeded, and now is the time when human beings have ever come closest to eternal life, because we know why people age and die.
The human body is composed of cells from the inside out, so human aging and death are essentially the aging and death of cells, so why do cells age and die? Isn't it possible to constantly divide new cells? In 1961, the biologist Heflik did an experiment in which he placed human cells in a petri dish to observe cell division, and found that there was an upper limit to cell division, and after about 50 times, the cell stopped dividing, thus proving that there was an upper limit to the number of cell divisions, which was later called the Heflik limit.
Why is there a limit to the number of cells that can divide?
Because the most important thing in the cell is the nucleus, there is genetic material DNA in the nucleus, and the cell has to copy the DNA during the process of division. The replication process of dna is not perfect, it may appear errors and leaks, once the errors and omissions occur, the mutated cells will appear, that is to say, the more times dna is copied, the greater the probability of errors and omissions, so a mechanism to limit the number of divisions appears. There is a substance called "telomeres" at both ends of the chromosome, and every division of the cell will lead to the shortening of the telomeres, and when the telomeres are exhausted, the cells can no longer continue to divide, and the body will inevitably die.
This mechanism seems cruel, but it is precisely because of the existence of this mechanism that organisms can become better and better, because the evolution of organisms depends on reproduction, but if there is no death, then there is no reproduction, so death is a cruel thing for the individual, but beneficial to the overall development.
The length of telomeres determines the number of divisions of cells, and the number of divisions of cells determines the extreme life of a life, the division cycle of human cells is average 2.4 years, according to 50 times to calculate, the human limit life expectancy is about 130 years old.
Some organisms have longer cell division cycles and more times, so they live longer, such as turtles. It can be seen that in order to achieve immortality, it is necessary to break this mechanism of limiting life, is this possible? Of course, even now, not all cells in the human body have a limit on the number of divisions, such as germ cells and hematopoietic stem cells, which can continue to divide until the end of human life. Why? Because there is a substance called "telomerase" in these cells, the role of this substance is to repair the DNA damaged in cell division, so that the telomeres will not be shortened by cell division.
Since telomerase protects telomeres from shortening due to cell division, is it possible to achieve immortality if we inject this telomerase into other tissue cells of the body?
Theoretically, this is true, but it may not be the path to eternal life, but the path to death. As mentioned earlier, the limit on the number of cell divisions is actually a self-protection mechanism, because an infinite number of divisions will lead to an increase in the probability of errors, so normal cells will be transformed into cancer cells, and cancer cells are terrible precisely because they have no limit on the number of divisions and can divide indefinitely. There is a large amount of active telomerase in cancer cells, so cancer cells will continue to divide and replicate uncontrollably, eventually causing the body to die rapidly. Conversely, if there is no telomerase in the cancer cells, then there is nothing to be afraid of the cancer cells.
Targeted drugs, I believe everyone has heard, simply put, the principle of targeted drugs is to use telomerase in cancer cells as a targeted marker, and then use drugs to inhibit the activity of these telomerase, without telomerase, cancer cells can not continue to divide and copy, and will naturally go to death.
So, the effort that humans are doing now is how to get rid of telomerase in cells, not all cells have this telomerase, because it is very dangerous to do so. It's ironic that the immortal cells of our hearts and minds are actually the cancer cells we hate. Theoretically, the immortality of the organism cannot be achieved, but with the help of future technology, it is feasible to combine humans and machines to achieve immortality, but if it is really realized, it will return to the original problem, that is, without death, there can be no new life, and the evolution of human beings will stop. Of course, human beings can also use the active evolution of science and technology to replace the natural evolution of living things, so the possibility of immortality cannot be completely denied.