Recently a study was published by Linkoping University regarding domesticated chickens. The researchers selected subjects that were less afraid of environmental disruptors, such as loud noises, lights, and etc., for breeding. These chickens were more suitable for domestication due to the reduced disruption of their behaviour.
They found that the size of the brains of the selected breeders was reduced over time, particularly in the brainstem IIRC.
Phys.org published an article regarding these results, which I read with interest. I have done some reading regarding human evolution this research sheds light on.
Our Cro Magnon ancestors had brains ~25% larger than our own back during the early dispersal of H. sapiens across Europe prior to the last ice age, while H. neanderthalensis also lived in Europe, and H. denisova in Asia as well. While I am unaware of cranial remains being found of Denisovans, Neanderthal brains were far larger than modern peoples, in fact larger even than Cro Magnons, and evidence indicates that both Denisovans and Neanderthals were incorporated into the human population that eventually led to us today. Basically everyone outside Africa today carries Neanderthal or Denisovan genes, or both, in their DNA.
All of these ancestral humans (just an assumption regarding Denisovans, that seems most likely to me) had larger brains than modern humans.
The research regarding chickens seems instructive regarding how human brains shrank: we have been domesticated.
In considering how human society self-domesticated I reflected on the fossil record of prehistoric peoples, as well as trends and events supported by such historical records as exist. Prehistoric cranial remains indicate that ~25% of deaths were caused by being bludgeoned in the head. This is the conclusion of archeologists and anthropologists from the fact that the left side of the front of the heads of ~25% of the cranial remains of humans in the fossil record show fatal blunt force trauma, such as would be caused by a right-handed assailant hitting them with a club.
War and intraspecific conflict seems to have been a feature of human society long into prehistory. After the use of written records began (the historical period), war has certainly been a dominant evolutionary force on humanity. It is easy to see that where one village or empire sends a force of armed thugs to kill the men of a neighboring village or empire and take their stuff, land, and women the primary selective pressure on breeding males would be their successful victory over such raids.
Those individuals that disagreed regarding taxation or other societal devices that best promoted military power, such as the draft, would be far less useful in military conflicts. Overlords commanding armies would happily kill anyone that reduced the power of their armies to defend the village or empire, and the people of that jurisdiction would need every sword arm to defend them.
Dissent was therefore amongst the most potent evolutionary forces selected against during prehistory, and even up to modern times.
Too smart for their own good. I reckon we've all heard that saying, and in this sense it would be very true. However, those very individuals would have been more likely to survive the aftermath of military defeat, less dependent on society and therefore more competent in circumstances where that support from society is gone to survive and successfully breed, making them strongly selected for in those circumstances.
These evolutionary influences seem to well predict the current societal situation, where there are large numbers of 'sheeple' that just toe the line when told to by overlords, and fewer numbers of dissenters that refuse to just obey, but point out the benefits of independence and freedom.
2020 seems to be intended to separate the sheep from the goats, as it were. From the looks of the vaccines, duplicity of government and enemedia, and plandemic fear-mongering, sheep are being corralled for slaughter, which will leave goats competent to survive alone able to successfully breed the next generation.
It may seem rather implausible to compare humanity to chickens, but when considering the needs of societies faced by war, by overlords faced with intraspecific competition their wealth and power depends on winning, and the historical facts of events like the Salem Witch Trials, the Inquisition, and slavery, the evolutionary forces seem obvious and parallel the needs of those husbanding livestock like chickens.
It's the squeaky wheel that gets greased, the obstreporous chickens that get served up in the pot, and those that go along get along - until everything breaks and only those able to get along on their own get along at all.
Everything is breaking in 2020.
Live free or die.