"Evolution!?" Yuan Haochen felt a little puzzled, "Do you think aging is the result of biological evolution?" ”

"So to speak!" Dr. Minchi replied. Pen % fun % Pavilion www.biquge.info

"Isn't evolution a process of continuous selection and optimization of species?" Yuan Haochen asked rhetorically.

Dr. Minchi helped his thick-rimmed glasses and replied in a characteristic low tone, "Aging is medically characterized as a progressive, generalized impairment of function, including increased environmental stress on the body, fragility of the body, decreased fertility, and increased risk of disease and death. Aging is obviously a negative biological phenomenon, and when we look at it from an evolutionary perspective, we wonder why the aging phenomenon of the body has not been more effectively eliminated by natural selection in the long evolutionary process. ”

Dr. Mingqi glanced at Yuan Haochen with wide eyes, but Yuan Haochen didn't want to answer the question, so he nodded and motioned for Dr. Mingqi to continue.

"This question has been discussed a lot in the biology community. An important phenomenon is that surveys of wildlife populations show that few individuals of wild animals survive to the point of age. For most wildlife populations, the risk of death from the external environment, such as harsh environments, predation by other predators, hunger and disease, cold and heat, etc., always occurs before they "age". In short, the animals are dead before they get old! ”

This means that natural selection has no chance of eliminating the aging gene! Alternatively, aging may not be a significant cause of death in nature. Or, nature does not need to orchestrate the process of aging in the genes of higher organisms. Even though it may be beneficial, however, natural selection usually doesn't "see" the side effects of aging. Moreover, even though immortality genes or longevity genes have been present in some individuals over a long evolutionary process, they have not been retained because they have not benefited the lives of wild species. ”

"On the other hand, human beings are even more unique in this field! When a perfect social system emerges. In fact, the human population has been basically wiped out or weakened, and the natural law of natural selection and survival of the fittest. It is easy to understand that the social welfare system will ensure the survival of the vast majority of human groups. ”

Yuan Haochen nodded thoughtfully and said: "With the development of science and technology, the productivity of human society has been greatly improved, and human beings have become a maverick group on the earth. For us, there will be no obstacles to basic survival, and even if some of the population with more resources have better living conditions, they will not necessarily go further on the path of evolution than others! ”

"Therefore, it is impossible for human populations to rely on natural evolution to increase their life expectancy!" Dr. Minchi said solemnly, "So, we can only find a way to slow down the pace of aging or, as you say, change the lifespan of humans through genetic technology!" ”

"But, it's hard!" Yuan Haochen said.

"As I mentioned earlier, there are at least 300 theories that cause aging in the biology community." Dr. Minchi continued, "At the molecular level, biologists' research has focused on some important macromolecular damage mechanisms. The main theories are: free radical theory, somatic cell mutation theory, protein change theory and waste accumulation theory, mitochondrial theory, telomere loss theory, etc. I'm sure you've heard of it. ”

"It's true that I have a special understanding of telomere loss theory." Yuan replied, "Telomeres are like a kind of [time delayed] fuse, our cells are used up after a certain number of divisions, and when the telomeres become too short, they cannot continue to divide. Scholars believe that when cells detect this, they start aging, stop growing, or begin apoptosis. ”

Why do cancer cells and sex cells not age during cell division, and what is the mechanism?

Before a cell divides, it must first duplicate chromosomes, resulting in two daughter cells, each with a complete set of chromosomes. The telomere theory holds that the chromosomes of newly fertilized embryonic cells have a long chain called pseudoDNA at the end, containing about 1,000 base pairs with no coding significance, and these pseudoDNA fragments, which are telomeres in biologists' mouths, have a protective function to keep the ends of chromosomes stable.

Without telomeres, chromosomes lose their stability, tend to stick together, and may even recombine in an abnormally bound way, leading to cell aging. Due to the specific form of the DNA replication method, it is not possible to copy the topmost part of the chromosome, so the replica is slightly shorter than the template.

This usually causes no problem during early cell division. However, with each subsequent division that the cell undergoes division, the long strands of these pseudo-DNA lose a small fragment, about 50 base pairs or so. When all of these protective bases are lost, the cell becomes severely dysfunctional and eventually tends to die. This theory, according to the theory, is why each type of cell has a certain lifespan boundary.

So why do cancer cells and germ cells (sperm, eggs) become "immortal" without being limited by the number of divisions?

Telomere theory holds that cancer cells and germ cells can produce an enzyme called telomerase. This telomerase repairs some of the damage that occurs at the end of the chromosome during cell division, so that the wound can be healed, and after each division, the telomeres can be rebuilt, so that the tendency of cell aging is avoided and the cell can be "immortalized".

"Your analogy of telomeres is very apt, but there are many problems from a biological point of view that cannot be explained by the telomere theory. Therefore, whether the shortening of telomere length is the cause of aging, we are still doing more in-depth research. Dr. Minchi added.

"I hope you can overcome the problem of aging as soon as possible, so that the life expectancy of human beings can be greatly improved." Yuan Haochen replied with a smile.

"I also hope to overcome these problems as soon as possible, otherwise my life will come to an end! Hohoho~"

Although Dr. Minchi talked about death, he didn't see any worry on his face, and he must have been an open-minded person who was used to seeing life and death.

"Aging is not the result of being programmed by DNA, but by DNA programming failure. The stability of living systems is constantly subjected to a wide range of internal and external pressures and slowly collapses in these situations. Unless we actively maintain it and constantly strive to maintain the balance, there will always be a more important competition for survival to face. Life will be weakened by time and consumed by fate, but we always insist on exploring and struggling without giving in! ”

"Teachable! Thank you very much! ”

Yuan Haochen said sincerely to Dr. Mingqi.

"You're welcome, Hao Chenjun!" Dr. Minchi waved his hand and said, "It's going to take some time to work on your blood and tissue cells. I will do this in secret, and I will inform you as soon as I reach any conclusion. And, without your consent, it won't be announced to the public! ”

"Thank you, Dr. Minch! Also, Chen Shuqin also asked you to take care of it! ”

"Huo Huohuo~, this matter is just a gesture, you don't have to take it to heart!"

After saying goodbye to Dr. Mingqi, Yuan Haochen came to the hibernation cabin where Chen Shuqin was placed.

He wanted to spend some time alone with her and tell her about some of the things that had happened in the past 18 years......

(To be continued.) )