Epigenetics, the Good and the Bad

Epignetics is what determines which genes express and how they express. Research on epigenetics for some reason has often focused on negative consequences.

In rodent research, scientists were able to induce a Pavlovian response to a smell that preceded a shock. The rodents would jump when the smell was present, even when no shock followed. And generations of rodents kept jumping, despite their never having been shocked at all. The Pavlovian response was inherited. In human research, scientists studied populations that had experienced famine. They looked at multiple generations where only the older generation had been alive during the famine. Yet all the generations following had higher rates of obesity. They inherited the biological preparation for famine.

One might start to think that epigenetics is a bad thing, almost like a disease. But that would be a mistake. Everything about who we are, good and bad, is shaped by epigenetics. To balance things out, I just came across some a more positive example. Health benefits get passed on as well. I would note, however, that this is what exacerbates inequality. This is why oppression and privilege get inherited not only through social conditions but in biology itself. This is all the more reason we should intervene to create the most optimal conditions for everyone, not merely the fortunate few.

This is why the political left emphasizes equality of results, beyond theoretical equality of opportunity. Opportunity is meaningless if it remains an abstract ideal disconnected from lived reality for most of the population. Telling people to get over the past is cruel and ignorant. The past is never past and, in fact, becomes imprinted upon the bodies of many generations, maybe across centuries. Historical injustices and transgenerational trauma are what our society are built upon, and much of it is within living memory, from the Indian Wars to Jim Crow.

It will require direct action to undo the damage and to promote the public good. That is the only path toward a free and fair society.

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Intergenerational transmission of the positive effects of physical exercise on brain and cognition
by Kerry R. McGreevy et al

Significance

Physical exercise is well known for its positive effects on general health (specifically, on brain function and health), and some mediating mechanisms are also known. A few reports have addressed intergenerational inheritance of some of these positive effects from exercised mothers or fathers to the progeny, but with scarce results in cognition. We report here the inheritance of moderate exercise-induced paternal traits in offspring’s cognition, neurogenesis, and enhanced mitochondrial activity. These changes were accompanied by specific gene expression changes, including gene sets regulated by microRNAs, as potential mediating mechanisms. We have also demonstrated a direct transmission of the exercise-induced effects through the fathers’ sperm, thus showing that paternal physical activity is a direct factor driving offspring’s brain physiology and cognitive behavior.

Abstract

Physical exercise has positive effects on cognition, but very little is known about the inheritance of these effects to sedentary offspring and the mechanisms involved. Here, we use a patrilineal design in mice to test the transmission of effects from the same father (before or after training) and from different fathers to compare sedentary- and runner-father progenies. Behavioral, stereological, and whole-genome sequence analyses reveal that paternal cognition improvement is inherited by the offspring, along with increased adult neurogenesis, greater mitochondrial citrate synthase activity, and modulation of the adult hippocampal gene expression profile. These results demonstrate the inheritance of exercise-induced cognition enhancement through the germline, pointing to paternal physical activity as a direct factor driving offspring’s brain physiology and cognitive behavior.