Another commentary on Jack Kruse's theses about health and evolution - this time he is addressing the separate emergence of bipedalism, and then the growth in the brain size, and it's an absolutely fascinating read, and I really believe this guy is onto something:
https://www.jackkruse.com/brain-gut-3-look-in-the-past-to-see-your-prologue/
However, I am surprised to see he didn't think of what I thought of after getting about half way through that.
Leaky Gut and Retroviruses - Humans are the only species plagued with autoimmune diseases
Firstly, a central component of the thesis is the part played by retroviruses, specifically HERV, a predecessor of HIV, and a virus that is present in shellfish, called Vibrio, which has a distinct marker in the presence of a molecule called 'zonulin', which basically led to what we now call 'leaky gut'.
All humans have leaky guts, to some degree. Leaky means that there can often be large breaches in the membrane through which quite large molecules like peptides can enter the bloodstream, and then act as exogenous hormones and neurotransmitters. Specifically, it makes our guts prone to sucking up every virus that passes through, the viruses alter the DNA in various organs, and sometimes the DNA gets into the stem cells and from that point on it also alters one's descendents. The interaction with the viruses also codes a lot of epigenetics in the form of immune factors and antibodies also.
Basically, autoimmune disease caused by viral infections was a positive adaptation for these early fishing homonids, and explains the rapid, and almost seemingly intentional mutation that led to the bipedal big brains we are now.
Viruses as a rapid adaptation mechanism
There is something like about 8% of our DNA in common with many well known viruses. Viruses can allow the organism to in fact mutate within their lifespan, and not just pass it on through their gametes, even epigenetics, are still bound by lifespan periods for their 'beta phase', testing the appropriateness of the change to the situation the organism is in.
This virus, Vibrio species, was responsible for causing this adaptation in the less strong protection in both the digestive system and Blood Brain Barrier (these are the two gatekeepers of our body), basically allowed humans to adapt within a generation to a new food source. This was necessary, because cold weather drove us out of the forests and onto the ground, where, of course, we faced things like cheetahs, tigers, wolves and lions and of course this is why we had to become hunters.
The virus from shellfish also basically defined the root of the modern human, as a fisherman. It seems to me to be very likely that possibly some humans changed in other ways, feet turning into flippers, sinus turning into a blowhole, the smooth skin becoming properly water-ready, for permanent immersion... I mean, we know that the Cetaceans originated from some kind of land animal.
Bipedal apes grew big brains because feeding from the ocean required a lot of tools and knowledge of seasons and celestial events
The moment at which humans became fishermen, infected with Vibrio, was the point at which the rigid ankle and big toe developed for the necessary terrestrial lifestyle of these proto-humans, was before the large brain developed. Cetaceans have brains that have a similar level of capability as higher apes, though highly specialised for sonar communication and navigation, which is probably (I have not studied cetaceans very closely, so bear with me, I may not say the correct thting) - nearly as complex as the human visual cortex.
We grew bigger brains because we became inventors. Even just opening shellfish requires a tool. Fishing hooks, nets, lines, spears, these early creatures got busy, working out how to pull more food out of the ocean with better tools.
The cetaceans brains did not grow quite as much compared to us, because they instead morphed into fish-like creatures, complete with a closeable air storage chamber in the front behind the skull, the ability to sense the geometry of the seabed and the presence of larger mobile objects amongst it, in pitch black, deep sea, at night.
I had to post this, since the idea seemed to me blatantly obvious. Kruse probably didn't go here mainly because his focus is more on understanding the evolutionary basis of modern illnesses (he is a spine surgeon, and got on the path after he realised that EVERYONE has osteoporosis.
The current crisis of the Human Species
Also, I realised that this inventiveness, is why we now stand on the threshold of causing a mass extinction event with our clever tools for increasing the harvest... This is a crisis that was baked in from the beginning, because this inventiveness allows our diet to get ahead of our ability to digest it - and probably Vibrio was not the only virus that altered our metabolism, because Vibrio allowed us to take the benefits from HERV DNA, and then pile in as many variations as possible with our guts sucking up every virus that passes by. This allows during-lifetime mutations of an organism that benefits survival.
Self-engineering
Really, this adaptation to use viruses as a method of rapid adaptation, is the precursor to self-engineering. It is likely, if we survive the coming extinction event, which is being caused by EMF radiation suppressing the signals that our cells depend on for their clocks, and I think where this is going, is that the survivors of the coming catastrophe are going to have abilities that we now scoff at, calling them fantasy and folly - psychic abilities, the use of quantum nonlocality to transmit information between individuals.
The seemingly fanciful ideas in the Resident Evil universe are heavily based on the concept of humans self engineering themselves with viruses, in the story, projected to be the cause of a global extinction event (RE3 covers this subject, specifically, and Alice develops psychokinetic abilities). I think that this is the way things are going forward, and because our biology is built on quantum physics, it makes sense that sooner or later, that entanglement as a means of communication, at least, would become a visible feature, and not just the stuff of legends.
Not only that, the maniacs in government bioweapons research labs, are just like the Umbrella Corporation, completely unhinged, and very dangerous. They are engineering viruses as weapons, but it is quite possible, indeed likely, that even if a virus manages to wipe out 99% of the human race, that the 1% that survives, will be radically mutated as a result. This could already be happening. It is likely that these engineered viruses are already starting to propagate through the population.
When higher apes became symbiotic with HERV, a lot of them died off at first. The same probably also happened to the protohumans that then went from bipedal to big brained in a very short period of time. This is probably going to happen again, the mechanism is very functional, and is why we are now so technologically advanced.
Note, that after learning about the interactions of EMF on our body clocks, I can easily and unequivocally say that humans will never leave the planet until we have our own inbuilt clocks, that are not influenced by our environment, and also, to be able to alter our DNA, through a process resembling software development, to adapt to colonising new environments. This even could include the hard vacuum of deep space, if we have the ability to communicate using entanglement and also, through the same mechanism, teleport.
The real factor that dictated why this planet is so full of life, is actually the iron core of the planet, which produces the magnetosphere, which blocks most of the worst ionising radiation from the sun, which would cause DNA to rapidly decline and lead to extinction.
So, if humans had an organ that produces such a magnetic shield against radiation, and an internal clock protocol system, that we could live, for example, on mars, or even as crazy as places like some of the watery moons of jupiter, like was described in Bruce Sterling's book 'Schismatrix'. Actually, the Shaper/Mechanist universe of Sterling, is very much along the same lines - you have on one side, genetic engineers, and on the other, computer/robot engineers.
In Schismatrix, the 'shapers' won. The genetic engineers.
It should be interesting to note that Sterling's main long story about this, Schismatrix, ends with the lead characters engineering themselves into squid-like creatures living under the ice on one of Jupiter's watery moons, communicating via skin colour changes.
It is the next logical step in evolution, if you ask me.