Home » News » PNAS Reports: “Conserved epigenetic sensitivity to early life experience in the rat and human hippocampus.”

PNAS Reports: “Conserved epigenetic sensitivity to early life experience in the rat and human hippocampus.”

A new paper in Proceedings of the National Academy of Sciences (PNAS) by Suderman et al. reports on the discovery of the ability of early life experiences to influence DNA methylation patterns in the hippocampal region of the brain. The researchers examined the methylation patterns of the hippocampus in humans who have been victimised by abuse. There was also a control group of non-abused persons. The results were then compared with rats who, as infants, had been subject to different maternal care.

The paper’s abstract reports,

Early life experience is associated with long-term effects on behavior and epigenetic programming of the NR3C1 (GLUCOCORTICOID RECEPTOR) gene in the hippocampus of both rats and humans. However, it is unlikely that such effects completely capture the evolutionarily conserved epigenetic mechanisms of early adaptation to environment. Here we present DNA methylation profiles spanning 6.5 million base pairs centered at the NR3C1 gene in the hippocampus of humans who experienced abuse as children and nonabused controls. We compare these profiles to corresponding DNA methylation profiles in rats that received differential levels of maternal care. The profiles of both species reveal hundreds of DNA methylation differences associated with early life experience distributed across the entire region in nonrandom patterns. For instance, methylation differences tend to cluster by genomic location, forming clusters covering as many as 1 million bases. Even more surprisingly, these differences seem to specifically target regulatory regions such as gene promoters, particularly those of the protocadherin α, β, and γ gene families. Beyond these high-level similarities, more detailed analyses reveal methylation differences likely stemming from the significant biological and environmental differences between species. These results provide support for an analogous cross-species epigenetic regulatory response at the level of the genomic region to early life experience. [emphasis added]

If this is correct, environmental conditions may have the ability to affect epigenetic chemical marking of DNA. Indeed, as this medicalxpress press release on the study put it, the study “confirms a biological process that embeds social experience in DNA in the brain and that affects not just a few genes but entire networks of genes.”

Pretty cool, huh?
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5 Responses to PNAS Reports: “Conserved epigenetic sensitivity to early life experience in the rat and human hippocampus.”

  1. Lest neo-Darwinians get false hope that the similarity of methylation patterns between mice and humans (analogous cross-species epigenetic regulatory response) somehow supports evolutionary thinking, I submit this recent article:

    Stark Differences Between Human and Chimp Brains – Brian Thomas, M.S. – Oct. 5, 2012
    Excerpt: The researchers used a new technique to peer in unprecedented detail at the methylation patterns of human and chimp DNA that they harvested from brain tissue of three cadavers of each species. They compared only those DNA sequences already known to have basically the same genes, ignoring the vast majority of DNA. If humans and chimps are close relatives, then they should have similar DNA methylation patterns in the areas of chromosomes that they have in common such as similar gene sequences.2 However, this team found major differences.
    In particular, human and chimp DNA methylation patterns, called “methylomes,” were very different between the two species’ brain tissue. The data statistically indicated that “major principal components separate humans and chimpanzees,” according to their report in American Journal of Human Genetics.1,3
    A second observation is that the very genes that were differently methylated “exhibit striking associations with several disorders, including neurological and psychological disorders and cancers.”1 These data show that methylation patterns in many cases can tolerate very little disruption, thus presenting another impossible hurdle for the evolutionary model to overcome.
    If humans evolved from chimpanzee-like creatures, then some unknown evolutionary process must have altered their methylomes. But since methylomes apparently cannot tolerate that much alteration, then the evolutionary story must be in error.
    Human and chimp species-specific and irreducibly complex methylomes refute human evolution.,,,
    (Zeng, J. et al. 2012. Divergent whole-genome methylation maps of human and chimpanzee brains reveal epigenetic basis of human regulatory evolution. American Journal of Human Genetics. 91 (3):455-465.)
    http://www.icr.org/article/7067/

    Also of note: This following study, in which the functional role of completely novel ORFan genes in humans was analyzed, the (Darwinian) researchers were ‘very shocked’ and ‘taken aback’ by what they found;

    New Genes, New Brain – October 2011
    Excerpt: “This is one of the first studies to look at the role of completely novel genes” in primate brain development,,, A bevy of genes known to be active during human fetal and infant development first appeared at the same time that the prefrontal cortex,,, Finally, 54 of the 280 genes found to be unique to humans were also highly expressed in the developing prefrontal cortex,,,, “We were very shocked that there were that many new genes that were upregulated in this part of the brain,” said Long, who added that he was also taken aback by synchronicity of the origin of the genes and the development of novel brain structures.,,, (From the PLoS article, author’s summary: We found these genes are scattered across the whole genome, demonstrating that they are generated by many independent events,,, Our data reveal that evolutionary change in the development of the human brain happened at the protein level by gene origination,,)
    http://the-scientist.com/2011/.....new-brain/

    footnote:

    From Jerry Coyne, More Table-Pounding, Hand-Waving – May 2012
    Excerpt: “More than 6 percent of genes found in humans simply aren’t found in any form in chimpanzees. There are over fourteen hundred novel genes expressed in humans but not in chimps.”
    Jerry Coyne – ardent and ‘angry’ neo-Darwinist – professor at the University of Chicago in the department of ecology and evolution for twenty years. He specializes in evolutionary genetics.

  2. It’s pretty clear that these, and other, epigenetic changes are part of the organism’s adaptation mechanisms. Having worked with abused adults, I know well there is obviously a major downside to them, as there is in the reported cancer-causing epigenetic changes.

    But since epigenetics accounts for a significant part of what organsisms actually are, the gung-ho talk of finding drugs and other therapies to reverse the changes and cure all kinds of diseases sounds naive, at least. It’s rather like the 21st century equivalent of lobotomy. One needs to find out the logic of the methylation before deciding one can dispense with it, but that requires assuming it has a purpose – and that’s teleology.

  3. Or we could do what might actually help people: tell them they can reprogram their brains with their mind.

  4. Has anybody seen this new article on epigenetics?

    http://www.the-scientist.com/?.....sing%20Lnc

  5. A significant paper, Andre.

    I like the chummy intro, on how the Just So Stories were inspired by Lamarck, not Darwin. He doesn’t mention what an inspiration Kipling in turn has been to evolutionists!

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