Here’s an excellent discussion of recent advances in our understanding about the control of plasticity and patterning in the human body:
https://link.springer.com/article/10.1007/s00018-023-05054-6
It is well-known that some lower animals have an incredible regenerative capacity. For example, salamanders can easily regenerate amputated limbs and planaria severed in two will regenerate an entire new organism from the severed halves, with the half that has the head growing a tail and vice versa. It is also well-known that humans and domesticated animals become very susceptible to cancer as they age.
It has been speculated that humans and other higher animals lack the regenerative ability of lower animals because of the tendency of higher animals toward cancer under certain conditions. And that the same mechanisms that promote regeneration could lead to cancer if not properly restrained. This diagram from the article summarizes the relationship between plasticity and patterning:
Interestingly, extensive research from the labs of Michael Levin at Tufts University has demonstrated that bioelectrical regulatory mechanisms come into play in both the promotion of regeneration and the control of cancer. The fact that bioelectrical patterns in the body can be altered in a way that induces limb regeneration and cures cancer suggest that a high level of both plasticity and patterning is an innate capability of higher mammalian systems. So, the question remains why evolution has selected for one over the other in higher animals.
It would certainly be problematic if higher animals lived for centuries and retained their reproductive fitness for most of their lifespans. Ecosystems couldn’t handle that. Yet, because of their advanced intellect and ability to transmit complex ideas across generations, humans would seem to be in a unique position to be able to leverage the power of high patterning and plasticity without necessarily experiencing the consequences of the destruction of society, culture, and ecosystems. However, this would only work across the entire population of the planet if people voluntarily chose not to reproduce or at least to not reproduce until they reached the endpoint of their reproductive fitness after several centuries or so. In addition, slowing down or ending the natural reproductive process could have ramifications for whatever future evolution would occur through natural selection. What if a lack of genetic variation resulted in our inability to adapt to a future environment despite our high level of plasticity and patterning? This is actually a common theme in science fiction, where advanced almost immortal races finally get their comeuppance.
So, it makes sense at the level of global ecosystems that higher animals do not live forever while reproducing endlessly. Yet, we are still faced with some questions about the innate capability of humans for a high level of both plasticity and patterning. Why do I say that this capability is innate rather than exogenous in the experiments to date? It is because the experiments at the labs of Michael Levin do not entail changing the genome, injecting embryonic stem cells, the use of nanotechnology to repair organ and tissue defects, or the continual ingestion of pharmaceutical compounds. In one of their most striking recent experiments on limb regeneration, they were able to stimulate the regeneration of an amputated frog leg after the administration of a drug cocktail just one time for about 24 hours. The nature of their works shows that they are able to use simple one-time signals to adjust the patterning “software” of the organism. 
Now, we also know from extensive research on the placebo effect that the actions of many drugs can take place without the administration of said drugs. Meaning that there are non-pharmacological mechanisms that can dramatically change the physiology of the body. This has been extensively shown in the treatment of symptoms or changes in physiological endpoints like lifting depression, lowering blood pressure, or regulating blood sugar. However, we also have the phenomenon of miraculous spontaneous healing without any therapeutic intervention. This is arguably also a type of placebo effect for which there is no known pharmacological analogue. Although,, the peculiar effects of many pharmacological agents on bioelectrical patterning may turn out to be the pharmacologic analogue of this type of miraculous healing.
So, now I will go out on a limb (pun intended). Stories of miraculous healing, spontaneous regeneration of amputated limbs, and extreme longevity have been staples of worldwide mythology for thousands of years. India and China have preserved many stories of great sages who had reputedly overcome death and disease and lived for hundreds if not thousands of years. The stories often include descriptions of various yogic and esoteric practices that somehow alter the normal trajectory toward death. There is abundant evidence that yoga, breathing exercises, and meditative techniques alter measurable physiological parameters in a way that is associated with improved health and longevity. For example, this recent meta-analysis on the association between meditation and telomere length.
I’m certainly not suggesting that these ancient tales provide some sort of factual evidence. Nor am I insisting that if there is any credence to the stories that the “mechanisms” will be fully explained at the physiological level. However, let’s set aside what else might be going on and look at what we already know. There appears to be an innate capacity of higher animals for both plasticity and patterning that can be induced with both pharmacological agents and optogenetic techniques. There is also abundant research on placebo effects and miraculous spontaneous healing. This does leave one wondering if certain advanced yogic techniques involving mental and breathing exercises might be able to leverage some of the effects that we are now observing in the labs of Michael Levin and others doing similar research. 
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