Chapter 108 18.2 Bypassing the central dogma

If nature can transmit information bidirectionally in organisms, it is possible to realize Lamarckian evolution based on the premise of bidirectional communication between genes and gene products.Pull evolution has huge advantages.When the antelope needs to run faster to escape the lion's mouth, it can use the body-to-gene communication method to guide genes to make fast-leg muscles, and then pass the innovative genes to offspring.In this way, the process of evolution will be greatly accelerated. However, Lamarckian evolution requires an organism to be able to efficiently index its genes.If an organism encounters a harsh environment—such as extreme altitude—it informs all the genes in the body that affect breathing and asks them to adjust.The body undoubtedly communicates messages to various organs through hormones and chemical reactions.The body can send the same message to the genes that do it, if it can be pinpointed.However, this is the missing step of bookkeeping.The body doesn't keep track of how it solves problems, so it can't be sure which gene is used to pump blood into the muscle in a blacksmith's biceps, or which gene is used to regulate breathing and blood pressure.Organisms have millions of genes that can generate billions of traits—a gene can generate more than one trait, and a trait can be generated by more than one gene. - The complexity of bookkeeping and indexing will far exceed the complexity of the living organism itself.

Therefore, rather than saying that the information in the body cannot be transmitted in the direction of genes, it is better to say that the information transmission is hindered because the information has no definite delivery purpose.There is no central authority in the genes that manages the traffic of information.The genome is the ultimate decentralized system—sprawling redundant fragments, massively parallel processing, no supervisor, no one to oversee everything. What if there was a way to solve this problem?True two-way genetic communication raises a host of intriguing questions: Will such a mechanism lead to biological advances?What else is needed for Lamarckian biology?Has a biological pathway to this mechanism ever emerged?If two-way communication is possible, why hasn't this happened yet?Can we outline a workable Lamarckian theory of biological evolution through thought experiments?

Nine times out of ten, Lamarckian biology requires a form of high complexity—a kind of intelligence—and most living things fall short of that level of complexity.Where complexity is plentiful enough to generate intelligence, such as humans and human organizations, and their robotic descendants, Lamarckian evolution is not only possible, but advanced.Acre and Littman have shown that computers programmed by humans can perform Lamarckian evolution. In the last decade (referring to 1984-1994), mainstream biologists have endorsed what some maverick biologists have preached for a century: if an organism acquires enough complexity inside it, it can use its body Teach genes the information they need to evolve.Because this mechanism is actually a hybrid of evolution and learning, it has the greatest potential in the field of artificial intelligence.

Every animal body has an innate and limited ability to adapt to different environments.Humans have adapted to life at much higher altitudes than they currently do.Our heart rate, blood pressure and lung capacity must and will adjust themselves to the lower air pressure.The same changes are reversed when we move to lower altitudes.However, there is a limit to the altitude we can acclimate to.For us humans, that's 20,000 feet above sea level.Above this altitude, the human body's ability to self-adjust reaches its limit and cannot stay for a long time. Imagine the living conditions of the people living in the high mountains of the Andes.They migrated from the plains to a place where the air was thin and not strictly speaking the best place for them to live.In the thousands of years of alpine life, their hearts and lungs and their bodies had to be overloaded in order to adapt to the high-altitude environment.Suppose a "weird" was born in their village whose body was genetically better equipped to handle the stress of altitude—say, a better variant of hemoglobin, rather than a faster heartbeat—then The weirdo had an advantage.If the weirdo had another child, the trait would likely be passed on in the village, since it would reduce the stress on the heart and lungs.According to Darwin's principle of natural selection, this mutation adapted to life in the highlands began to dominate the gene pool of the small village population.

At first glance, this might seem like classic Darwinian evolution.But for Darwinian evolution to work, organisms must first live in this environment for many generations without benefiting from genetic modification.Thus, it is the body's ability to adapt that allows the population to persist until the day the mutants emerge, and thereby correct their genes.Adaptations spearheaded by the body (physical adaptations) are absorbed by the genes and made their own over time.Theoretical biologist Waddington called this transition "genetic assimilation."Cybernetic expert Gregory Bateson calls it "physical adaptation."Bateson compares it to legislative change in society—changes initially introduced by the people before they are enacted into law."The wise legislator," writes Bateson, "rarely pioneers new rules of conduct, and often confines himself to confirming into law those rules which have become customary to the conduct of the people." In the technical literature, this genetic certification is also considered It is the Baldwin effect, named after the psychologist Baldwin. He first published this concept in 1896, calling it a "new factor in evolution".

Let’s use the mountain village analogy again, this time in the Himalayas, in a valley called Shangri-La.Residents there are physically adapted to altitudes of up to 30,000 feet—10,000 feet higher than Andean inhabitants—though they are also capable of living at sea level.Like the inhabitants of the Andes, this variation has been passed down through generations and written into the genes of these inhabitants.Comparing the two alpine villages, the Himalayans now have a more flexible, malleable body and are therefore inherently more evolutionarily adaptable.This seems a bit like a typical example of Lamarckian theory, except that giraffes that can stretch their necks to the maximum can use their bodies to guard this adaptation until their genes catch up.In the long run, as long as these giraffes can adapt their bodies to various extreme stresses, they will eventually win the competition.

Whoever has a flexible form of expression reaps the rewards—this is the essence of evolution.A body that can adapt to the environment is obviously more advantageous than a rigid body; when adaptation is needed, the latter can only wait for the arrival of mutations like a pie in the sky.Physical flexibility, however, "comes at a price."Organisms cannot be equally flexible in all respects.Adapting to one stress weakens the ability to adapt to another.Writing adaptations into the genes is more effective, but that takes time; in order to achieve genetic change, the pressure must be kept constant over a considerable period of time.In a rapidly changing environment, keeping the body flexible and malleable is the preferred compromise.A nimble body can foresee—or rather—try out every possible genetic improvement, and then keep its eye on them like a hound on a grouse.

And that's not the whole story.It is behavior that controls the body.For whatever reason, the giraffe had to first want to reach the high leaves, and then had to try again and again.Humans had to choose to migrate to villages at higher altitudes for some reason.Through behavior, an organism is able to search its options, to explore the space of adaptations it may acquire. Waddington once said that genetic assimilation, or the Baldwin effect, is actually how acquired skills are transformed into innate traits.The real crux of the problem, however, is the control of traits by natural selection.Genetic assimilation kicks evolution up a notch.Whereas natural selection turns the dial of evolution toward optimal traits, physical and behavioral adaptations not only provide the dial of evolution, but also tell which direction to turn and how far away from optimal traits to turn.

Behavioral fitness affects evolution in other ways as well.Naturalists have confirmed that animals are constantly wandering out of their adapted environments, making homes in places that "don't belong" to them.The coyote moved quietly far south, and the mockingbird far north; then, they both stayed there.In this process, the adaptation initially arises from a vague will, and the genes approve of this adaptation and endorse it. If this kind of evolution originating from ambiguity is applied to individual learning, it will slide to the dangerous edge of classical Lamarckian theory.A species of finch has learned to sting insects with cactus spines.This behavior opens up a new window for the bird.By learning this intentional behavior, it changes its own evolution.It is entirely possible—even if unlikely—that it learned to influence its genes.

When some computer experts use the word "learning," they mean a loose, cybernetic concept.Gregory Bateson sees physical flexibility as a form of learning.He doesn't see much difference between the search by the body and the search by evolution or the mind.In terms of this interpretation, it can be said that "the flexible body learns to adapt to stress". "Learning" should be an adaptation acquired over a lifetime rather than generations.Computer experts do not distinguish between behavioral learning and physical learning.Crucially, both forms of adaptation involve a search of the adaptive space over the individual's lifetime.

Organisms have a lot of room to reinvent themselves during their lifetime.Robert Reed of the University of Victoria in Canada pointed out that organisms can respond to changes in the environment through the following plasticity: Morphological plasticity (an organism may have more than one physical form.) Physiological adaptation (The ability of an organism's tissues to adapt to stress.) Behavioral flexibility (an organism's ability to do something new or move to a new place.) Intelligent choice (an organism's ability to make choices based on past experiences.) Tradition-guided (an organism can refer to or learn from the experience of others) Each degree of freedom here represents a direction along which an organism can find better ways to reshape itself in a coevolutionary environment.Considering that they are adaptations acquired by an individual during a lifetime and can be genetically assimilated later, we call these five options the five variants of heritable learning.