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Can The Environment In Which Our Long-Deceased Ancestors Lived Still Affect Our Mental And Physical Health? In this essay, I will explain what epigenetics refers to and how the concept came about. Proceeding, I will outline a number of studies and observations from recent years which suggest that epigenetics play a role in transgenerational adaptation, and that the implicated epigenetic alterations are correlated with environmental changes – both physical and mental. Finally, I will conclude that the environment in which our long-deceased ancestors lived does appear to be capable of having an effect on our mental and physical health, but that more research is needed if we are to understand this phenomenon in a more wholesome way – and, that such research will become more and more possible now that we know what we are looking for.
Kaati et al. (2007) explain how “epigenetics refers to heritable changes in gene function that cannot be explained by changes in DNA sequence” (Kaati et al., 2007, p.785). One of the first allusions to this sort of phenomenon came from Marcus Pembrey, who carried out some important research on the mechanisms underlying the inheritance of Angelman syndrome, which subsequently “helped elucidate the normal phenomenon of genomic imprinting in humans” (Pembrey, 2010, p.268). Pembrey found that the specific alteration of the DNA sequence associated with Angelman syndrome did not always necessitate the onset of the condition, but rather the alleles of the gene could be “active or silent depending on which parent they came from” (Pembrey, 2010, p.268). As such, the inheritance of Angelman syndrome was shown to not only rely on alterations of the DNA sequence of a specific gene; but also upon a force which “determines whether the gene is silenced or active in the next generation” (Pembrey, 2010, p.268).
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In recent years, there has been an increasing well of evidence emerging which supports the idea that epigenetic phenomena represent a vitally important element of human development. One such piece of evidence came from a study by Bygren et al (2001) which showed that the longevity of a person’s life appears to be partially determined by their “paternal ancestors’ nutrition during the slow growth period (the years just prior to the onset of puberty)” (Bygren et al., 2001, p.53). The study observed a strong correlation between high levels of food availability during a paternal grandfather’s slow growth period and a shorter than average life for the grandchild (Bygren et al., 2001, p.53). Thus, the experiences of the paternal grandfather appear to have a trans-generational effect, and the question which immediately arises is: how exactly could information about the life of the paternal grandfather be passed on in this way and produce the observed effect?
Wolf Reik (2005) explains how, through studies of children Beckwith-Wiedemann syndrome, he noticed a heightened incidence of the syndrome presenting in babies conceived through IVF treatment. Proceeding, he explains this phenomenon by claiming that “the mere fact of human embryos having been in a culture dish or manipulated could alter their epigenetic switches” (Reik, 2005). If his claim is correct, it means that genes can be switched on or off by the conditions of the environment in which they find themselves and that this effect could be passed on through generations. This hypothesis would go some way in explaining the observations of Bygren et al (2001); as variations in diet affect the biochemical make-up of our bodies – this, in turn, could potentially cause certain genes to be turned on or off (thus creating a knock-on effect for subsequent offspring, though how far-reaching these effects could be was unclear simply based on Reik’s observations).
Skinner et al. (2010) made a discovery which lends support to Reik’s hypotheses. They
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conducted an experiment in which he exposed rats to vinclozolin (a common fungicide normally used on crops) and thereby caused methyl groups of atoms to attach to some of the genes present in rats sperm/eggs. Once attached to a gene, a methyl group acts as an offswitch (Begley, 2010). But Skinner et al. went on to show something further, which had not been previously observed… Their experiment examined the fungicide-exposed rats offspring for four generations, and it was discovered that the affected genes had been “permanently modified” (Begley, 2010) for the lineage – leading to physical mutations prevailing through the generations.
Alarmingly, epigenetic modifications do not appear to be confined to purely physical causes and effects (such as nutrition and longevity, or toxin-exposure and physical mutations), as Yehuda et al. (2010) outline. In research which examined the offspring of women who had been exposed to the terror-related events of 9/11, it was noted that the women who subsequently suffered from PTSD went on to have children with lower cortisol levels than normal (leaving the children more susceptible to PTSD than the average child) and that the women who were in the latter stages of pregnancy during the events passed on more of the effects than the women in early stages of pregnancy (Yehuda et al. 2005). This suggested “there was something that was being transmitted in the late stages of pregnancy where the mother's symptoms were having some effect on the development of the offspring's cortisol system” (Yehuda, 2005). As such, it appears mental events such as those which relate to PTSD, like the physical events described by Skinner et al. (2010), could have the power to generate an epigenetic transgenerational knock-on effect.
In conclusion, there is much evidence to suggest that the environment in which our longdeceased ancestors lived still affect our mental and physical health today. Yet, despite the
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evidence, there still remain many who are highly sceptical of the phenomenon (Pembrey, 2005). This may be partially due to the fact that the concept of epigenetics appears to contradict the widely-accepted model of how genes operate, and thus how evolution works. However, there are those who suggest that epigenetic imprinting may actually be “used as a means of some sort of trans-generational adaptation” (Pembrey, 2005), and so rather than contradicting the current model of the role of genetics in evolution – epigenetics may actually compliment it and develop the theory further. Nevertheless, the field of epigenetics is still in a relatively early stage, and so more research is certainly needed if we are to discover exactly how big a role epigenetics play in transgenerational development. Only through further enquiry will we move away from speculation based on the small, isolated, cases and timid sample-sizes which were involved in the examples I have outlined. We can move, then, towards a more wholesome understanding of lifespan development which can seek to grasp the balance of the effects which shape the ways each and every one of us develop; a balance which, based on the rapidly emerging evidence, must include a place for epigenetics. Up until this point, it has been difficult to study epigenetics due to the simple fact that our ancestors did not keep records for this purpose – after all, they did not even have the concept of epigenetics. But now that we know what to look for, we can begin to keep records which will make comprehensive epigenetic studies far more possible as we proceed into the future.
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Reference List:Begley, S. (2010). “Sins of the Grandfathers”. Newsweek; Vol. 156 Issue 19, p48-50. Bygren, L.O., Kaati, G., & Edvinsson, S. (2001) “Longevity determined by paternal ancestors’ nutrition during their slow growth period”. Acta Biotheoretica. Issue 49, Vol 1. pp. 53-59. Kaati, G., Bygren, L. O., Pembrey, M., & Sjostrom, M. (2007). “Transgenerational response to nutrition, early life circumstances and longevity”. European Journal of Human Genetics (2007) 15, p.784–790. Pembrey, M. E. (2010). “Male-line transgenerational responses in humans”. Human Fertility, December 2010; 13(4): p.268–271. Pembrey, M. (2005). Speaking in “Horizon: The Ghost in you Genes”. Distributed by British Broadcasting Company (BBC). Reik, W. (2005). Speaking in “Horizon: The Ghost in you Genes”. Distributed by British Broadcasting Company (BBC). Skinner, M. K., Guerrero-Bosagna C, Settles M, Lucker B (2010) Epigenetic Transgenerational Actions of Vinclozolin on Promoter Regions of the Sperm Epigenome. PLoS ONE 5(9): e13100. doi:10.1371/journal.pone.0013100 Yehuda, R., Engel, S.M., Brand, S.R., Seckl, J., Marcus, S.M., & Berkowitz, G. S. (2005). Transgenerational effects of posttraumatic stress disorder in babies of mothers exposed to World Trade Center attacks during pregnancy. J Clin Endocrinol Metab 90: p.4115–4118. Yehuda, R., Flory, J. D., Pratchett, L. C. (2010). “Putative biological mechanisms for the association between early life adversity and the subsequent development of PTSD”. Psychopharmacology (2010) 212: p405–417. Yehuda, R. (2005). Speaking in “Horizon: The Ghost in you Genes”. Distributed by British Broadcasting Company (BBC).