Epigenetics and Environmental Ethics IV: Did Aristotle and Aquinas Discover DNA?


by Shea Robison (@EpigeneticsGuy)

Epigenetics and Environmental Ethics I

Epigenetics and Environmental Ethics II

Epigenetics and Environmental Ethics III

The next step in the chain of reasoning that produces both the modern self and the genome, and which also helps to explain both the scientific and non-scientific objections to epigenetics, is the elaboration of the soul in relation to the body, principally through the scholastic theology of Thomas Aquinas (AD 1225 to AD 1274).

In defining the fundamental nature of persons, Aquinas and other scholastic theologians of his time borrowed heavily from Aristotle for their definitions of basic terms such as substance, form and matter as they pertain to the soul and the body. ‘Matter’ in this Aristotelian sense should not be understood in the purely tangible sense that we understand today, but rather as “that which has the potentiality to be actualized into an existent entity,” while ‘form’ is to be understood as “the inherent principle which makes the existent entity what it is.”[1] In other words, matter is not of itself real because it cannot exist by itself without this form, and this form is only actualized through matter. ‘Substance’ is therefore neither form nor matter, but rather the combination of the two which results in a determinate individual able to exist independently.[2]

This Aristotelian typology was applied by Aquinas and the other scholastic theologians to explain the soul as the source of physical individuation which constitutes an individual person distinct from its surroundings and from other persons. In Aquinas’ own words—in language remarkably reminiscent of the description of genes in the Modern Synthesis—not only is the soul “the primary actuality of a physical bodily organism,”[3] the soul is also “a substance in the manner of a form that determines or characterizes a particular sort of body,”[4] to the extent that “it is impossible that a soul, one in species, should belong to animals of different species.”[5] In other words, “the type of essence (soul) instantiated defines what type of entity the particular entity is—it defines the natural kind to which the individual belongs,”[6] such that for Aquinas and the other scholastic theologians living substances were distinguished by their souls, which imbued them with their basic species-specific attributes.[7]

The conceptual similarities between this theological soul—which is the seat of our contemporary ethics—and scientific DNA—which is the focus of contemporary genetics—are, I hope, at least apparent at this point. These conceptual similarities between our ethics and our science, because they share the same ontological roots, are also are the locus of the challenges of epigenetics to both our contemporary ethics and genetics.

For example, if you substitute ‘DNA’ for ‘soul’ in Aquinas’ own words you get “[DNA] is the primary actuality of a physical bodily organism” and that “[DNA] is a substance…that determines or characterizes a particular sort of body,” and that “it is impossible that [DNA] one in species, should belong to animals of different species.” By way of comparison, the definition of DNA given on Nature magazine’s Scitable website is as a substance which “a human, a rose, and a bacterium have in common…along with every other organism on Earth,” but also which “ultimately determines each organism’s unique characteristics.”[8] Likewise, the entry for DNA on simple.wikipedia describes how “DNA stores information that tells the cells how to create that living thing,” and how “parts of this information that tell how to make one small part or characteristic of the living thing – red hair, or blue eyes, or a tendency to be tall – are known as genes.”[9] The only basic aspect of DNA that is not mentioned by Aristotle and Aquinas is how it is inherited; this will be addressed in subsequent posts.

That the roots of this form/matter ontogeny which at once both produced the modern self and the modern genome extend all the way back to Aristotle, prompted Max Delbrück, one of the founders of molecular biology and a Nobel laureate himself, to suggest the appropriateness of a posthumous Nobel prize for Aristotle “for the discovery of the principle of DNA.”[10] Others have also remarked upon the deep conceptual similarities between this Aristotelian and Thomist concept of the soul and DNA. Thomas Jackson, in an article published in The Guardian newspaper, observes how well our contemporary concept of genes reflect these ancient and Medieval ideas:

“Most of all, though, Aquinas would have been entranced by the idea of genes. If ever there were an Aristotle-friendly idea this is it. Genes illustrate both of Aristotle’s two fundamental principles. One is that immaterial forms do not exist in some nebulous heaven, as Plato thought, but are embedded in material things themselves. This is exactly what we find in genes.”

Jackson also observes how our modern concept of genes reflect “Aristotle’s other big idea,” which is “act and potency”:

“Everything is potentially the something else that it is already ordained to be. Bronze becomes statues, not primroses, live humans become dead ones, not alarm clocks. The whole essence of genes is that they are potentially the actual things that they already in some essential sense are. Genes are potentially phenotypes and phenotypes are activated genes.”

Jackson does not pursue the implications of this congruence between this theological concept of the soul and the scientific conception of genes, but the molecular biologist and bioethicist Alex Mauron does in an article in Science titled “Is the Genome the Secular Equivalent of the Soul?” In this article Mauron writes:

“With the complete human genome sequence now at hand the notion that our genome is synonymous with our humanness is gaining strength. This view is a kind of “genomic metaphysics”: the genome is viewed as the core of our nature, determining both our individuality and our species identity. According to this view, the genome is seen as the true essence of human nature, with external influences considered as accidental events…Part of the prima facie plausibility of our genome as the definition of our humanness comes from the blending of ideas of nature, stability, immutability, and genes – if a trait is in the genes, there is nothing that can be done about it.”[11]

With these last observations of Mauron, we are getting closer to explaining—at least in part—the roots of the antagonism against epigenetics often observed from geneticists, as well as the implications of epigenetics for environmental ethics. There are a couple of other important coincidences between this theology of souls and the science of genes which are relevant to the challenges presented by epigenetics which will be discussed in more depth in the next post in this series.

One coincidence mentioned by Mauron is the emphasis both Aristotle and Aquinas place on substance versus accidents in the formation of things, and its corollary in genetics of Crick’s central ‘dogma’ of molecular biology which details how information emanates out of but not back into DNA. The other coincidence is the idea of souls as essences which precede and endure after the dissolution of the individual body, which has its genetic corollary in the transmission of the genome through inheritance.

For now it is enough to say that one of the fundamental challenges of epigenetics to conventional genetics involves the inheritance of environmental ‘accidents.’ While conventional genetics allows that environmental influences may affect the expression of the genome, these accidents are supposedly discarded via processes such as genomic imprinting, rendering a pristine copy of the form or soul of the species to the next generation. Research in epigenetics, though, demonstrates that in certain contexts these accidental influences are not erased and are actually passed on to subsequent generations—in Thomist/Aristotelian terms, the pure form of the soul becomes accidental, which cannot be within the ontological framework erected to support this notion of the soul; in genetic terms, traits acquired during the life of an organism are inherited, which within the ontological framework erected around modern genetics also cannot be. In both cases, substantial changes are required to incorporate this new evidence from epigenetics.

Is there substance to these historical connections I am drawing between the development of this ‘self’ as the seat or our ethics and the genome and genetics? Or is this just historical happenstance? What further support is needed to validate this connection? What do you think?

I am curious to hear what you think so far. Leave your comments below and I will respond.

Also, if you find these thoughts I’ve shared interesting and worthwhile, Like this post, Reblog it, or Tweet about it using the buttons below.

[1] J.P. Moreland and Stan Wallace, “Aquinas versus Locke and Descartes on the Human Person and End-of-Life Ethics,” International Philosophical Quarterly (Vol. Xxxv, No. 3 Issue No. 139 Sep. 1995).

[2] Aristotle. Metaphysics: 1029a28

[3] Thomas Aquinas, Commentary on Aristotle’s De Anima, trans. K. Foster et al (London: Kegan Paul, 1951), II.1. 233.

[4] Ibid. II.1. 221

[5] Thomas Aquinas. The Summa Theologica of St. Thomas Aquinas, trans. Fathers of the English Dominican Province (New York: Benziger Bros. 1981), I.76.2.

[6] J.P. Moreland and Stan Wallace, “Aquinas versus Locke and Descartes on the Human Person and End-of-Life Ethics,” International Philosophical Quarterly (Vol. Xxxv, No. 3 Issue No. 139 Sep. 1995).

[7] Mauron, A. “Is the Genome the Secular Equivalent of the Soul?” Science 291.5505 (2001): 831-832.

[8] http://www.nature.com/scitable/topicpage/DNA-Is-a-Structure-that-Encodes-Information-6493050

[9] http://simple.wikipedia.org/wiki/Genetics#DNA

[10] Delbruck, M. “Aristotle-totle-totle.” Of Microbes and Life. Ed. J. Monod and E. Borek. New York: Columbia University Press, 1971. 50-55

[11] Mauron, A. “Is the Genome the Secular Equivalent of the Soul?” Science 291.5505 (2001): 831-832.


6 thoughts on “Epigenetics and Environmental Ethics IV: Did Aristotle and Aquinas Discover DNA?

  1. An excellent and informative article revealing the impact of Aristotelian biology on the modern science of microbiology and epigenetics. Certainly the Thomists have been particularly helpful in propagating and valuing the brilliant insights of Aristotle and the relevance of those insights to both modern philosophy and philosophy of science.

    What is apparently missed in this fine blog post regarding ‘Did Aristotle and Aquinas Discover DNA?’ is the fact that the key concepts relevant to DNA were those of Aristotle, those of Aquinas being derivative, though deeply integrated by the fecund mind of Aquinas. What is missed, explicitly is the revolutionary idea (in its time) that what is carried by the sperm or the seed is not a copy of its parent, i.e., not a homunculus or tiny little man that develops merely through growth, but rather–and this is the key–a plan for the creation of the new instance of that organism. The idea that a plan, transmitted in a physical form (the seed or sperm), was revolutionary at the time of its discovery, and truly anticipated the idea of DNA qua a plan that directs the development of the embryo from its single-celled fertilized ovum. This is the key idea, that a plan for the actualization and not a copy or instance of that actualization in immature form, is what the seed or sperm carry in a physical form in the transmission of life. (Of course, there was no microbiology in Aristotle’s day, so the female’s egg was not understood as carrying anything that contributes to the development of the individual, other than its supply of nourishment, such as is provided by the egg yoke to the developing bird or reptile zygote. We now know the second important key to the propagation of life: the joint contribution of separate, though highly similar, plans submitted by both parents. This is the secret of sexual reproduction! We now understand the potentialities lying in the genotype that emerge and are actualized in the phenotype.) For those interested in this topic, I wrote a blog page regarding this issue, entitled ‘Aristotle, DNA and The Unmoved Mover’ http://bioperipatetic.com/about-emergence/dna-the-unmoved-mover/

    Again, congratulate Mr. Robinson for his excellent blog article and his blog site, ‘The Nexus of Epigenetics’, as a whole. It shows how science and philosophy must work together to discover and properly understand and and apply the truth underlying nature’s unfolding and its implications for human flourishing qua human being. But it must be emphasized, in my view, that science fundamentally depends upon philosophy for its epistemological and ontological foundations as well as the validity of its methods, and not the other way round. Philosophy teaches us how we know the world (epistemology) and how the world must be, qua being (ontology), and applies these disciplines to the facts and theories offered by science. Without this cooperation both science and philosophy fail in their proper respective purposes and goals. On this latter topic, I have written a blog page here: http://bioperipatetic.com/science-ontology-and-epistemology/


    • Thank you for your thoughts and for taking the time to write a response to this post.

      I read through your post on the necessary connection of philosophy and science, and I could not agree more. This blog and my overall project are also efforts to demonstrate through discussion of the emergence of the science of epigenetics this inevitable overlap of science, which so often masquerades as just an objective method, and the questioning of the assumptions of a science. The references to the impacts of Aristotle and Aquinas on contemporary genetics are my tentative steps in this direction, so I appreciate the additional background you have provided. There is much more to be said in this regard, which I hope to continue to work out, but you have also provided a number of additional sources and resources for anyone interested in the histories of biology, genetics in particular, science in general and philosophy.

      Thank you again for your time and effort, and the additional information and insight you have provided.


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