Hormones are substances produced by living cells that circulates in body fluids (such as blood) or sap and produces a specific often stimulatory effect on the activity of cells usually remote from its point of origin. How do hormones fit into Scripture? Let’s look at a small example.
Unlike most other proteins, the biological sciences tell us that hormones are carried to their target cells via the bloodstream. Informed by God, Hildegard tells us that after Adam’s sin, man’s blood carried within itself: 1) sweet, but deadly, poison, i.e., hormones; 2) shameful and turbulent acts, thus increasing the body’s appetite for those very crimes carried in the blood, i.e., slavery to sin; and, 3) impure filth which changed Adam’s blood into a liquid of pollution.
We know Adam and Eve experienced shame as a result of their nakedness. Arguably, lust, fear,  and stress were probably at play as well. All the physical consequences of concupiscence described above are attributable to the production of hormones. All those hormones would secrete into the bloodstream to respond to sensual stimuli coming from the opening of their eyes. Both shame and stress are associated with, among others, the production of the hormone cortisol. Lust of the flesh (aka biological/chemical love — utterly different than spiritual love, a distinction greatly misunderstood in today’s culture) produces several addictive hormones. Examples are dopamine, testosterone, oxytocin, and vasopressin.
Fear is an emotion associated with the fight or flight hormone adrenalin. Other physical consequences of concupiscence include pain in childbirth (relaxin, oxytocin, adrenaline, prostaglandins), hunger (ghrelin), greed, avarice, etc. Some might be confused by the fact that Jesus suffered hunger in the desert (Mt. 4:2, Lk. 4:2) and yet, at the same time, we know that he was not born with any trace of concupiscence.
Aquinas explains the apparent contradiction this way, “the penalties, such as hunger, thirst, death, and the like, which we suffer sensibly in this life flow from Original Sin. And hence Christ, in order to satisfy fully for Original Sin, wished to suffer sensible pain, that He might consume death and the like in Himself.” Put another way, Jesus’ body was completely subject to his human soul (he did not inherit Original Sin). His soul possessed the power to both will and allow his body to experience the consequences of Original Sin — without having sinned. St. Paul writes, “For our sake he made him to be sin who knew no sin, so that in him we might become the righteousness of God” (2 Cor. 5:21).
Without supernatural grace and the strength that the soul receives from it, our salt of DNA will enslave. Our flesh will use disordered sensual appetites to initiate the production of reward hormones. In turn, the chemical rewards will entice us to equate happiness with the satisfaction of those appetites and the avoidance of any discomfort. How strong is the power of hormones to enslave us? Remember the hunger hormone, ghrelin? Is your willpower strong enough to overcome the powerful urges created by ghrelin? Can you resist it by not eating anything for a day, a week, a month, or even forty days? How about those hormones leading to addictions? How hard is it for a smoker to stop smoking? How hard is it for an alcoholic to stop drinking? Typically, I would not classify food as an addiction, but it can be for certain people. How hard is it for a drug addict to stop taking drugs? How about sex addictions? All the addictions, as mentioned above, can be identified as addictions to the feelings that hormonal chemicals generate. Furthermore, they also instill the powerful appetite that must be fed — or else you pay a heavy biological price.
What necessarily follows from the repeated satisfaction of hormonal appetites is self-centeredness instead of other-centeredness. This self-centered reliance on chemically-induced feelings were, and are, the sad state of fallen man. We seek hormonal happiness at the expense of spiritual joy. We are even confused about what constitutes true happiness (if we are even remotely aware there is a difference).
For example, there is a vast difference between biological compassion and spiritual compassion. Fallen man’s intellect is easily fooled by compassion originating in the flesh. Biological compassion is fed by releasing hormones, primarily oxytocin, that cause a person to feel good. This hormonally induced feeling fools the person into thinking that an act of real good has just been performed. Often, the reality is that it was only an apparent good (i.e., a perceived good leading to the biological reward of oxytocin, which is not a real good benefiting the eternal soul).
The Holy Spirit — and only the Holy Spirit — dwelling within the inner heart (the spirit) motivates spiritual compassion. The Spirit leads man to acts focused on obtaining ultimate and eternal happiness for others. There is a litmus test that will help us distinguish biological compassion from spiritual compassion. If the particular act performed is an objectively sinful matter, then physical compassion — and only biological compassion — is at the root. The Holy Spirit will never prompt anyone to be an accomplice to another person’s sinful behavior! PERIOD!
 Hildegard of Bingen, Scivias, trans. Columba Hart and Jane Bishop (New York: Paulist Press, 1990), 113.
 Ibid., 417.
 Ibid., 257-258.
 Merriam-Webster.com Dictionary, s.v. “hormone,” accessed January 22, 2022, https://www.merriam-webster.com/dictionary/hormone.
 Aquinas, Summa Theologiae, I, q. 95, a. 1.
 Hildegard, Scivias, 113.
 Lewis, Michael, and Douglas Ramsay. “Cortisol response to embarrassment and shame.” Child development vol. 73,4 (2002): 1034-45. doi:10.1111/1467-8624.00455.
 Wendy Zukerman, “Stress Gives Reef Fish Wonky Ears,” http://www.abc.net.au/science/articles/2009/04/27/2553465.htm: ABC Science, April 27, 2009 (accessed 04/27/2009).
 Doidge, The Brain That Changes Itself, 114.
 Hormone Health Network, “Hormones and Health,” Endocrine Society, http://www.hormone.org/hormones-and-health/what-do-hormones-do, January 1, 2008 (accessed May 29, 2008).
 Doidge, The Brain That Changes Itself, 119.
 “Hormones of Pregnancy and Labour,” Society for Endocrinology, https://www.yourhormones.info/topical-issues/hormones-of-pregnancy-and-labour/, March 2018 (accessed 6/07/2021).
 Hormone Health Network, "Ghrelin,” Hormone.org, Endocrine Society, https://www.hormone.org/your-health-and-hormones/glands-and-hormones-a-to-z/hormones/ghrelin, November 2018 (accessed 7 June 2021).
 Aquinas, Summa Theologiae, III, Q. 1, Art. 4.
 Francois Jamart, Complete Spiritual Doctrine of St. Therese of Lisieux (New York, NY: Alba House, 1996), 109.
 University of California – Berkeley, “Social Scientists Say Compassion Is Humans’ Strongest Trait”, News-Medical, http://www.news-medical.net/news/20091210/Social-scientists-say-compassion-is-humans-strongest-trait.aspx, December 10, 2009 (accessed 04/30/2012).
 Leen, Rev. Edward. The Holy Spirit. (New York, NY: Sheed & Ward, 1939; Sceptor Publishers, 1998, 2008), 15-16, 18.