Human PV work (f)
W = P \int_{n_1}^{n_2} d\sigma dn \,Depiction of PdV work: scene from the 2004 film Mean Girls, depicting the volume change ΔV, at constant atmospheric pressure P, around the A-list girl clique (the alpha female, second to left), as they move through the hallway and chemically react with the other students. [2]
In equations, the expression:

P \Delta V \,

is the called “pressure volume work”, or PdV work, and is the product of the pressure P of the system times the change in volume ΔV in the system, in some process or reaction, and, in the views of American physical chemist Gilbert Lewis, "must always be done when a process occurs at constant pressure", whether the process be reversible or irreversible, and is described as “the work done against the constant pressure of the atmosphere” or specifically the work that the atoms and molecules of the system do against the constant pressure of the atmosphere. [1]

History
The 1652 invention and public demonstrations of the Guericke engine, by German engineer Otto Guericke, was the first visualization of the power of pressure volume work or rather the ability of a small volume increase (or decrease) to be equivalent to the power or strength of 30+ men, and the later realization that to increase volume requires that one lift, in effect, 62-miles of atmosphere, upward or outward to make space for the new volume.

The 1678 gunpowder engine built by Dutch mathematical physicist Christiaan Huygens showed that combustion produced “vacuum change” owing to the change in volume of the oxygen and hydrocarbon reactants transforming into water and carbon dioxide products, which was thus associated with pressure-volume work; although this was not stated mathematically.
Indicator
Diagram of the indicator (vertical part), which gives a reading of pressure, invented by James Watt and Matthew Boulton in 1790, and the sliding board (horizontal part) and pencil tracer (attached to the indicator), invented by John Southern in 1796, which makes an 'indicator diagram', the pressure-volume graph (drawn on the sheet).

The 1796 indicator and indicator diagram, depicted adjacent, invented by Scottish engineer James Watt and his employee John Southern, provided the first PdV diagrams of pressure-volume work in a quantifiable graphical way.

Human reactions
In human thermodynamics, each human molecule carries with it a certain amount of personal space, which varies from person to person. One significant factor in this variation is physical attractiveness; another is height. It has been found through measurement that the more attractive a person is the more personal space or rather "volume" he or she carries around with them. In the words of attractiveness researcher Nancy Etcoff: [3]

“Very attractive people of any size are given bigger personal space and territory; which they carry around with them.”

Hence, when any given person enters a room or area of humans a volume change will accrue, which will correlated energetically to to a measurable amount of PΔV work.

See also
● Rise and fall of civilization
● Papin engine

References
1. Lewis, Gilbert and Randall, Merle. (1923). Thermodynamics and the Free Energy of Chemical Substances (pg. 157). McGraw-Hill.
2. (a) Thims, Libb. (2007). Human Chemistry (Volume One). Morrisville, NC: LuLu.
(b) Thims, Libb. (2007). Human Chemistry (Volume Two) (mean girls, pg. 550). Morrisville, NC: LuLu.
(c) Mean Girls – Wikipedia.
3. Etcoff, Nancy. (1999). Survival of the Prettiest – the Science of Beauty. New York: Anchor Books.

Further reading
● Thims, Libb. (2006). “High School Cafeteria Seating Distributions”, IoHT publications.

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