Cover story: "Love: the Chemical Reaction", in the February 2006 (Valentine's day) issue of National Geographic.

In human chemistry, a human chemical reaction is a change in which one or more human molecules or human molecular compounds (the reactants) form a new compound or human molecular structure (the products). [1] The following is American author Thomas Dreier’s 1948 description of marriage as a human chemical reaction: [3]


Moreover, in the context of social interactions, Dreier seems to have been the first to coin the term “human chemical reaction”, albeit he uses it in the context of a point interaction:

“There are certain people we dread to meet because whenever we talk with them our ideas clash. Hard as we try, we cannot seem to avoid becoming argumentative, if not positively combative. We realize that it is our strongly held personal opinions for which produce uncomfortable reaction—for that is what is what it is—a human chemical reaction.”

The following is a famous 1933 quote by Swiss psychologist Carl Jung on this topic: [4]

“The meeting of two personalities is like the contact of chemical substances; if there is any reaction, both are transformed.”

This is a modern interpretation, in which people are viewed as molecules, of the older "love the chemical reaction" view of life and romance, in which human interactions are described in mechanistic terms, just as in a standard chemistry textbook. The following is another description by Dreier, in which a pair, each married at the time, met and fell in love, both getting divorces and remarrying each other: [3]

“Here two persons reacted as certain as powerful chemicals react when united. We need not pass on the rightness or wrongness of their action to recognize the inevitability of strong reactions to certain human chemical combinations.”

History

See main: Human chemical reaction (history)

German writer Johann Goethe was likely the first to draw out human chemical reactions, in the William Cullen reaction diagram style, in preparation for the writing of his 1809 Elective Affinities, although the fact that he destroyed all his manuscripts and notes to this novella leaves the question unresolved. [5] The best verbal example from the novella comes from chapter four. Goethe was followed by Jeremy Adler (1969), Libb Thims (1995), Christopher Hirata (2000), David Hwang (2001), Chanel Wood (2007), and Surya Pati (2009).

Overview
The detailed understanding of what constitutes a human chemical reaction is very difficult subject, which is not easily discerned on first pass. A very simple reaction is the combination reaction, in which two un-acquainted people, A and B, meet in time, fall in love (as in “love the chemical reaction”), and transform into a bonded relationship or couple AB. This is depicted by the following chemical equation:

A + B → AB

When reactions become more complicated, however, many unseen factors begin to accrue, such as coupling effects, and second-by-second exchanges in the mechanism. To even begin to describe human interactions in terms of basic chemical reactions is very difficult. Americans biologist Lynn Margulis and science writer Dorian Sagan, in their 1997 book What is Sex?, for instance, try to describe sex via a crude chemical equation. They ask “why do we scientists ignore the basic arithmetic of live?” In answer to this, they state “in biology 1 + 1 does not equal 2, but rather 1 + 1 = 1, as in sperm (Sp) plus one egg (Eg) equals one fertilized egg.” [2] In chemical reaction terms, their hypothetical formula amounts to:

Eg + Sp → EgSp

In which the EgSp represents a fertilized egg. The conclude “is this why our efforts to predict sexual behavior with fancy computer models are bound to fail?” In more detail, however, the full mechanistic analysis of what constitutes the energetics and movements associated with sex is more involved, as detailed in the next section.

The adjacent video (at the 1:00 mark), gives another humorous attempt to describe sex in terms of a chemical equation, using the symbol of Mars (♂) to represent the male organism or man and the symbol of Venus (♀) to represent the female organism or woman, resulting in the following sex diagram:

♂ + ♀ ⇌ Baby

Using this diagram, the person in the video draws the sperm, with a head and a wiggle tail, moving from the male ♂ to the female ♀ and describes how “latex” can block the progress of the reaction. The speaker also incorrectly uses a two-way reversible reaction arrow to define the sex/reproduction reaction. The correct formulation is to use a one way arrow, signifying that the formation of an embryo and later an infant is an irreversible process. If, however, the couple or female decided to opt for an abortion, a completely different reaction mechanism would be used.

Reproduction reaction

See main: Human reproduction reaction

The core reaction in human life, through which 85% of people go through is a reproduction reaction (double displacement reaction) in which two people, A and B, react over the course of a number of years to form an attached couple A≡B and an new child C, the overall mechanism of which is shown below:

A + B → A≡B + C

The detailed mechanism of the human reproduction reaction involves a day-by-day accounting of the germ cells, as they are exchanged between partners, and slowly form into a embryo, then into a child, which for a dozen years or more remains attached to the parental structure, then begins to detach. Technically, the basic reproduction reaction, in which one child is conceived and raised into adulthood, in mechanistic terminology, is what is called a double displacement reaction, of the form shown below:

AB + CD → AD + BC

In human chemical terms, a man Mx parts with the genetic component of his sperm Sp; a woman Fy parts with the genetic component of her egg Eg; and they both emerge newly ‘transformed’ after the birth of their child, in the form of a new molecular structure, i.e. parents bonded into a working chemical relationship MxFy with an attached embryo SpEg uniting them:

MxSp + FyEg → MxFy≡SpEg

Soon thereafter, still being attached significantly to the parental structure MxFy, the sperm-egg molecular entity SpEg, in the shape of what is called a morula, i.e. a globular solid mass of blastomeres formed by cleavage of a zygote, will begin to transform or grow into the structure of a young child Bc. Given time, the child will eventually begin to detach, in a predominate manner, from the parental structure:

MxFy --- Bc → MxFy + Bc

In this manner, the newly created human molecule Bc will go off into the world as a newly formed individual. As we see, human chemical reactions are quite intuitive and very easy to depict. Do note, however, although simplistic-looking, these human chemical reactions actually embody principles and theories far greater in complexity and extent than can be detailed in this short book. It must be understood that the second-by-second mechanism underlying the above expressions, invariably, need to be explained in terms of only two components: electrons and photons. To do this is quite a tedious process and many new perspectives on life must be digested.

General reactions
Other basic human chemical reactions are tabulated adjacent. The actual description of which requires a detailed analysis of material and energy exchange and change of relationships per reaction.

References
1. (a) Thims, Libb. (2007). Human Chemistry (Volume One), (preview), (pg. 42, 117-18). Morrisville, NC: LuLu.
(b) Daintith, John. (2004). Oxford Dictionary of Chemistry. Oxford: Oxford University Press.
2. Margulis, Lynn and Sagan, Dorion. (1997). What is Sex? (pgs. v-vi). New York: Simon & Schuster.
3. Dreier, Thomas. (1948). We Human Chemicals: the Knack of Getting Along with Everybody (pg. 57, 96). Updegraff Press.
4. Jung, Carl G. (1933). Modern Man in Search of Soul (pg. 49). Harvest Books.
5. Goethe, Johann. (1809). Elective Affinities. Penguin Classics.

External links
● Human chemical reaction - human thermodynamics glossary.