Today we will talk about a topic that many people are curious about:
How far are human beings from achieving the goal of immortality?
Let's take a look at the current state of human lifespan.
Human life expectancy has been increasing over the past two hundred years, with the global average human life expectancy reaching around 72 years in recent years, compared to 52.5 years in 1960, according to WHO statistics. Look at the following chart of this life expectancy trend, it can be said that it is all the way up...
(Source: Network)
But is this growth endless?
In fact, the increase in human life expectancy is more due to the improvement of the human living environment and the progress of disease prevention and treatment, such as the decline in the mortality rate of cancer or cardiovascular diseases, or the decline in the mortality rate of infectious diseases in children [1], rather than really making people "not old" or "aging slowly".
According to known, relatively uncontroversial records, the world's longest-lived person is only 122 years old.
(Yana Carmante 1875/2/21-1997/8/4 Image Source: Network)
Obviously, it is aging.
As we age, the organs in the human body inevitably begin to age...
The heart, brain, liver, kidneys and skeletal muscles, these vital organs are prone to functional degradation.
In addition to organs, endocrine glands also continue to age, more and more endocrine hormone levels are reduced to below normal levels; in addition, intestinal cells are also aging, the ultimate result is that the elderly will have intestinal problems, especially those over 120 years old, their intestines can hardly absorb nutrients.
Therefore, immortality but old age, in exchange for a low-quality state of life, eternal life and maintaining the vitality of the human body, is called alive.
(Source: "Crazy Primitive Man")
As we all know, human growth and development are determined by the ability of cells in the body to divide.
There is a special structure called telomeres in dividable cells, and one of the most famous theories proposed by the academic community about why people age is telomere theory [3].
So what are telomeres?
Telomeres are special "cap" structures made up of a small piece of DNA and protein that is present at the end of the linear chromosomes of eukaryotic cells.
Think of it as a plastic sheet at the end of the lace, just as a plastic sheet protects the lace from splitting and blossoming, and the telomeres prevent DNA from being "worn" out.
Every time a cell divides, the telomeres on the chromosome are cut once, and the more they divide, the shorter the telomeres become, until they disappear, the cells can no longer divide, and then the functions of the body will be abnormal, and the aging process will also occur.
Is the law of telomere shortening completely unstoppable? Not really.
There is also a thing called "telomerase" in cells, which is mainly responsible for the synthesis, repair and prolongation of telomeres, thereby enhancing the proliferation ability of cells in vitro.
In other words, the length (life) of telomeres is determined by it.
Based on the above information, let's open our minds
If humans can ensure the activity of "telomerase", let it constantly repair, synthesize, and prolong telomeres, and cells continue to divide, can't people live forever?
Needless to say, there are really animals in the animal kingdom that use this mechanism to "live forever", that is, lobsters.
Image source: Stand Cool Helo
Misplaced the picture, put a new one.
Because lobsters maintain telomerase activity and their telomerase is widely present in all types of tissues, their telomeres are not depleted by cell division [4].
This allows lobsters to "grow indefinitely" without slowing, weakening or losing their fertility as they age.
Conversely, older lobsters may be more fertile than younger lobsters, and even if they die, most of them die due to excessive energy consumption or infection during hulling, rather than "aging".
Isn't that exciting?
Unfortunately, compared with lobsters, in normal human cells, telomerase activity is regulated quite strictly, and only in hematopoietic cells, stem cells and germ cells, which must constantly divide, active telomerase can be detected.
If telomerase is reactivated or appears where it shouldn't be, cell division may spiral out of control and cancer will occur...
In general, many advanced malignancies are not easy to control because of the activation of telomerase and the stability of telomeres, allowing cancer cells to have the ability to continue to divide [5,6].
Although it is a pity, but another way of thinking, if we can find specific telomerase in cancer cells early and target and control these telomerases, then we can also play an anti-tumor role.
In addition to starting with cells, academia has tried many other paths, saying two that everyone hears a lot.
1. Nanotechnology
People's impression of nanotechnology may also come from the latest armor of Iron Man in the movie "Avengers 4", but in fact, the application of nanotechnology in machines is still too early.
(Source: Avengers: Endgame)
In real life, the role of nanotechnology in delaying aging is mainly in the fields of medical cosmetology.
For example, some substances with anti-aging functions, such as antioxidants, are transported with nanoparticles and transported to specific parts of the body, thereby improving the function and vitality of this part of the organ. Nanotechnology is also being studied in areas such as repairing damaged organs and tissues in humans [7].
2. Powerful artificial intelligence (AI) combined with whole-brain simulation [8]:
Artificial intelligence, in simple terms, is to make the machine also have the ability to think like a human, and its current application in the field of medicine is very extensive.
For example, for humans, understanding aging requires monitoring many different types of data sets, such as blood test data or gene expression data. These datasets change slowly over the course of human life, and vary significantly among different populations, involving millions of parameters.
Artificial intelligence has powerful computing power, can find the law in a large number of data, so as to predict the factors of human aging in advance, and help propose solutions to delay aging.
In addition, there is an extreme idea of research on artificial intelligence, that is, to completely transfer your consciousness and the way of thinking of your brain to robots, and when your bodily functions are problematic, robots will continue to survive in your place, because your thinking is there, you are there. After that, you may become a robot with a human brain.
However, although this research direction seems novel and is loved by science fiction works, reality still has a long way to go, and there are some privacy and ethical issues, such as the memory and thinking style of your brain when it is first transferred to the robot, and your brain is exactly the same, but over time, it will gradually evolve some differences, and it is likely that the robot will not be you in the end.
To sum up, there are many objective reasons and technical problems that have led to our inability to achieve immortality, and there is no real "elixir of immortality". Even many anti-aging oral products, the so-called related experiments are only done on animals, and there is no clinical evidence.
So why not do clinical trials on people?
It is true that some institutions are doing it [9], but anti-aging experiments take at least decades to come to a conclusion, so at least so far, there have been no reliable results directly in humans.
Although human beings have no way to achieve eternal life, it is precisely because of their limited life expectancy that we will cherish life incomparably.
In a limited life, doing more meaningful things and living a valuable life is more worth working hard than "living long".
Review expert: Luo Tianming | Doctor of Immunology, Tsinghua University, Postdoctoral Fellow in Virology, Peking University Medical College, Assistant Researcher of School of Basic Medicine
bibliography
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[2] Jeune, B. et al.. in Supercentenarians (eds H. Maier et al.) (Springer, 2010)
https://www.guinnessworldrecords.com/news/2020/10/the-worlds-oldest-people-and-their-secrets-to-a-long-life-632895
[3] Razgonova, Mayya P et al. “Telomerase and telomeres in aging theory and chronographic aging theory (Review).” Molecular medicine reports vol. 22,3 (2020): 1679-1694. doi:10.3892/mmr.2020.11274
[4] Bowden TJ, Kraev I, Lange S. Extracellular vesicles and post-translational protein deimination signatures in haemolymph of the American lobster (Homarus americanus). Fish Shellfish Immunol. 2020 Nov;106:79-102. doi: 10.1016/j.fsi.2020.06.053. Epub 2020 Jul 28. PMID: 32731012.
[5] Trybek, T., Kowalik, A. Kowalska, A." Telomeres and telomerase in oncogenesis (Review)". Oncology Letters 20, no. 2 (2020): 1015-1027. https://doi.org/10.3892/ol.2020.11659
[6] Maciejowski, J., de Lange, T. Telomeres in cancer: tumour suppression and genome instability. Nat Rev Mol Cell Biol 18, 175–186 (2017). https://doi.org/10.1038/nrm.2016.171
[7] Ventola CL. The nanomedicine revolution: part 2: current and future clinical applications. P T. 2012 Oct;37(10):582-91. PMID: 23115468; PMCID: PMC3474440.
[8] Zhavoronkov, A., Bischof, E. & Lee, KF. Artificial intelligence in longevity medicine. Nat Aging 1, 5–7 (2021). https://doi.org/10.1038/s43587-020-00020-4
[9] Tarantini Stefano, Valcarcel-Ares Marta Noa, Toth Peter et al. Nicotinamide mononucleotide supplementation rescues cerebromicrovascular endothelial function and neurovascular coupling responses and improves cognitive function in aged mice. [J]. Redox Biol, 2019, 24: 101192.
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