Why do we get old? No not like this. Why does the mouse age 40 times faster than us? And the whale is 2 times slower? Is there any fundamental law of physics that determines the aging of living systems?
It is strange to see that in the 21st century there is still someone who still believes that “entropy” is responsible for aging, namely the
second postulate of thermodynamics , which says that in isolated systems, entropy cannot decrease. By the way, this “cannot go down” for some reason often transforms into “must grow”. At the same time, the time frame in which she is obliged to do this is not voiced. Well, okay, it makes no sense to try to discuss shades of gray, when we have green: organisms are not
isolated systems. Quite the contrary, they only do that they absorb energy from the outside, using it for various needs, including reducing their entropy. And it may very well be that the distinctive feature of living organisms is a more effective increase in external entropy compared to non-living systems, as the hypotheses of biophysicist Jeremy Ingland tell us (
1 ,
2 ).
By the way, physicists asked questions about the relationship of living systems with entropy from time immemorial - reflections on these topics are found in the works of the 19th century, but probably the first deep and large-scale analysis was the book
“What is life?” One of the most famous physicists of the 20th century, Erwin Schrödinger. Although in the masses, I think, his cat is better known:
In his book, Schrödinger noted that one of the key differences between living systems and non-living systems is that they can “create order from chaos,” that is, reduce their entropy. He even put forward the definition that life “feeds on negative entropy,” although he later realized that he had stupidly stupidly, and many times explained that in reality life, of course, “feeds” on free energy, which he spends on reducing or maintaining his entropy on one level, but sedimentary - in the form of the concept of
negentropy - remained.
Well, thanks to the physicists for bringing the theoretical base under quite obvious observations. Yes, living systems, or rather their genes, have learned very well how to cope with entropy, namely, using energy from the outside, reduce it during reproduction and keep it low for years or even decades after birth. Accordingly, the only reason for the fact that after a certain age the entropy of the body begins to increase - this is because the gene program ceases to lower it properly, or even
starts up its replicator at the expense (like a vmch. Salmon). Moreover, for each species, this age is different, differing between species by orders of magnitude, which clearly indicates that this process is not due to some law of physics, but is a biological adaptation.
What prevents genes to keep their replicators alive for centuries or millennia? Yes, nothing interferes. Apparently, they simply do not need it - and so everything turns out quite well. Moreover, an unnecessarily long life of replicators can, on the contrary, even be detrimental to the long-term survival of genes. After all, gene co-operatives (species) play their “Hunger Games” not alone, but in a multi-billion dollar multiplayer, where each link in the predication pyramid groping for a delicate temporary balance depends on the links under it. In such conditions, successful long-term existence is hardly possible without multi-level cooperation and adaptation to the ecosystem as a whole.
By the way, social insects are the best illustration of the stinginess of genes in dosing the lifespan of their creatures. The royal caste lives by 1-2 orders longer than the working one, despite the fact that they have the same genes. Recently, a very
interesting article about termites (which, by the way, was
finally being degraded to cockroaches) came out, showing that their queen's mechanisms for protecting DNA from transposons (harmful “jumping genes”) are equally active both in youth and in old age, but in working individuals this protection very quickly turns off. By the way, the same defense mechanisms (
piRNA ) against transposons are used in our germ cells, but not in somatic cells.
It would seem, everything is clear - they don’t want genes to allow working individuals to live long. Specially they are killed, to put it simply. But no, the victims of the Stockholm syndrome will find an excuse for the killer genes. “It’s probably too energy-consuming to support the expression of transposon protection genes in all termites,” they say:
“It would be, after all, it was not necessary to maintain an active piRNA signaling pathway.”
What does “too energy consuming” mean? In the queen, which incidentally lays 20,000 eggs
a day , is not expensive, but is it expensive in an employee? And what about energy, about food? Or again about a certain magic “resource”, which exists only in the fantasies of adherents of the trade-off? And where is that trade-off, if the queen lives 20 years, and the working individual only a few months?
There is no trade-off . And with entropy somehow the queen does not have problems.
An even more glaring example of the voluntarism of genes in choosing the life span of their creatures is the
Monarch butterfly . In the summer, these butterflies live for only a few weeks, and migrate south to wintering in the fall, and such migrants live up to 7 months. Moreover, these same migrants first fly thousands of kilometers long, and fly back in the spring, and the females set off on their way back pregnant.
The most interesting thing is that for the huge difference in life expectancy (RV) between migrants and non-migrants from the Monarchs, there is only one JH1 hormone from the family of “
juvenile hormones ”. If you
enter it to the butterflies in the laboratory , they live 2 times less than the control, and if on the contrary block its production, then the butterflies live 1.5 times longer. The graphs below show a huge difference (3 times!) In the median prostate cancer between those who received JH1 in addition (blue curves) and those whose production was blocked (red). Top row - females, bottom - males.
By the way, juvenile hormones are responsible for the development of many insects, including social insects. Most likely, it is during development that they
determine for the bees to become the queen, and to whom the worker.
So on thermodynamics, the genes found control a long time ago. And the fact that they can maintain the entropy of the body at a sufficiently low level to allow the queen to live for 20 years, but do not use this skill for an employee, means only that it is simply unprofitable for genes, and not theoretically impossible.
Moreover, its own entropy genes have been kept low for billions of years. And we are just the tool that helps them in this deadly fight. Only
“Fatality!” Falls almost exclusively on our share, that is, it is our mortality that ensures immortality to genes. I do not know about you, but I am tired of this situation. I did not engage in kamikaze replicators. Therefore, I believe that it is necessary to urgently do everything possible to throw off the yoke of genes, and free our personalities from the bonds of biology. Genes get out!