I find the term oversensitive immune system vague and this article shows how very little modern science truly understands the total scope of what the immune system is and the totality of all its functions.
The theory is predicated upon an idea that because neanderthals had lived in much more septic and harsh environments
compared to the emerging neo humans, that they evolved an overactive immune system which made them susceptible to allergies, and this was passed down to modern humans when they interbred.( Bullshit)
I have often wondered about the true dynamic of the human immune system as a driving force in evolutionary adaption. The current scientific model is an oversimplified and truncated cartoon caricatured myth, that doesn't come close to grasping the full power and magnitude inherent within the human immune system. I postulate that there is much more to the immune system than simply fighting off invading microbes and rebuilding of damaged and degenerate tissues. Within the larger scope.... the immune system modulates genetic expression, in order to bring the organism into alignment with an ever changing environment. It maintains a homeogeniality between the myriad of variant forms which interchange genetic information within an ecosystem .
The antigens produced in reaction to foreign proteins for example, are actually mutagenic substances which the immune system produces to induce epi genetic changes. What science has diagnosed as an "allergy" is in actuality a mutagenic immune response, in which the release of histamines, cytokines, antigens, ect are reacting in accord with the natural order and are serving a vital function. This whole notion of allergy's being an immune overreaction is a gross oversimplification.... the allergic reaction is exactly as it should be, generally speaking, the body knows no ideology and reacts to foreign proteins with the appropriate response as best designed within the genetic code. Allergic reaction could be seen as the catalyst by which adaptation to aberrant material which is unfamiliar to the previous forms...out of the allergic response the immune system engages in a progress of learning by which it can alter genetic expression to best cope with adverse situations.
This by no means...means that the adaptations are 100% successful, or that they occur without negative consequences.....In extreme cases where the entire diet is transformed within a short period there is monumental genetic upheaval, and many traits have to be sacrificed or transformed....when intrinsically alien and aggravating proteins, mutagens, carcinogens, endotoxin, etc is imposed upon a group of people, without any previous immunity, it may take multiple generations of suffering and there could possibly be many positive attributes which must be sacrificed in order to become equitably adapted to a point where the immune system returns back to homeostasis... be it humans to wheat...or a koala bear to eucalypti.
Modern humans with "throw back genes" whom are exhibiting allergic "overreactions", (if there is any validity to it at all) could signify a positive phenomenon of active resistance to aberrant environmental conditions... The fact that their immune system is fighting something is a good sign, and if the proper understanding was applied then it may be possible to eliminate the underlying causal factors, and return the body back to homeostasis.
Another (far out) theory regarding modern human disease being responsible for the overtaking of neanderthals and the other forms of human at the time, is that of the proactive mutagenic weaponized viral antigens evolved by the most highly adaptable emergent hominids, mutilated the DNA of the other sub species to the point where only those whom interbred and aligned themselves with modern humans survived. Much in the same way how native Americans where decimated by small pox, and the ones who survived the ordeal interbred with the invading population. Its possible some subgroups like Neanderthals being isolated for hundreds of thousands of years, and having no previous exposure, were hit hard by the viral antigens of a highly evolved biological phenomenon, which remains a mystery to science.
Not only is the human immune system endowed with great power to modulate genetic expression, but it may produce powerful engineered viral antigens capable of infecting and altering the genetic expression of others within the breeding range. This could serve a number of different functions, such as to bring into closer genetic viability separate subgroups of humans. In the same way mothers milk passes on antibodies, these viral antigens could be part of a higher level of cooperative evolution, by which an individual once exposed to mutant antigens can spreed the genetic alteration and modulation to all others within the breeding population. Successful modulations of this sort helps facilitate interbreeding of once divergent subgroups into more highly evolved unified forms.... and unsuccessful ones are weeded out through natural selection.
There is indeed much mystery within the systems of biological life, and the human immune system may be just as important a factor in our ascension from the lower animals as is our mind...these two forces may in some as yet to be discovered way be working interconnectedly in accord with a higher intelligence.