Genome complexity: epigenetics in humans shows slim results (Introduction)

by David Turell , Monday, April 04, 2022, 20:51 (745 days ago) @ David Turell

The results are sketchy and in trouble to gain acceptance:

https://www.the-scientist.com/features/does-human-epigenetic-inheritance-deserve-a-clos...

"The concept of epigenetic inheritance has long been controversial. Some researchers hope that new data on cross-generational effects of environmental exposures will help settle the debate.

"This question of what’s passed down from parent to child is complex and has often been socially and politically charged, says Baccarelli, who now chairs the environmental health sciences department at Columbia University’s Mailman School of Public Health (and who attributes his truffle love to his childhood in Umbria). The nuances of inheritance are perhaps most commonly framed as the age-old debate of nature versus nurture, the pervasive idea of a tug-of-war between deterministic genetic sequences and changing environmental influences—a dichotomy that scientists have long criticized as an oversimplification, given the complex interactions between genetics and the environment. Over the last couple of decades, however, scientific and public conversations about inheritance have grappled with an apparently separate, non-genetic dimension of inheritance.

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"As data trickle in, arguments about which, if any, aspects of epigenetic inheritance hypotheses are likely to apply to humans continue to simmer in the literature. Many scientists still lament what they view as hype, misreporting, and an unhelpful blurring of definitions in the field, particularly when it comes to distinguishing between inter- and transgenerational effects. Some researchers in this field, meanwhile, say they feel their work’s been unduly maligned. Many people don’t appreciate how much effort it’s taken to get research on epigenetic inheritance recognized, Mansuy says over email, adding that “collecting data and publishing [in this discipline] require more efforts and time than in more classical fields.” She also points to struggles that she and some of her colleagues have had obtaining funding for projects on epigenetic inheritance in mammals in recent years.

"Other scientists say they’re still prepared for concepts of epigenetic inheritance to fail, either because the relevant mechanisms turn out to be vanishingly rare in humans or because their effects end up being negligible compared to everything else influencing development. “I don’t think we’ll ever point to a single study across multiple generations [and say], ‘They finally showed it!’” Breton says. “I think it’s going to end up being the cumulative evidence. The more papers that show the same set of relationships, that’s where we’re going to end up saying, ‘OK, I think we start to believe this’—or maybe we don’t. Maybe in the end it was all the other life stuff that was getting in the way that really made it look like an association, and really it isn’t.”

"For LUMC’s Heijmans, reduced interest in epigenetic inheritance now as compared to several years ago offers a welcome opportunity for epigeneticists to focus efforts on more-fruitful research directions, he says, noting that “there are more-relevant nuts to crack.” He has been studying how prenatal or early-life environments might influence the epigenome, and whether epigenetic alterations can be used as biomarkers to predict disease risk within a person’s lifetime. This could in theory “help us in identifying vulnerable individuals, and also monitoring [their] health,” he says—in other words, “helping them using epigenetics. That’s where I think it can be quite relevant.'”

Comment: A huge article which hashes out all the conflicting results, which I have skipped to simply show us recent thinking without reading enormous discussions of minor relevance. It is obviously not a solution for the problem of understanding how speciation works. It appears to be related to very minor alterations.