For his unit cohesion study, Herr interviewed Army infantrymen, Navy submariners and Air Force drone operators. Partway into the two-year study Herr had an epiphany. “The ‘aha’ moment,” Herr tells Danger Room, “was seeing a link between an objective physiological phenomenon — knowing the effects on the body and brain of stress hormones — and how that matched with all the literature on unit cohesion.”

In other words, Herr had a vision of the stress hormones that our glands pump into our bloodstreams in life-or-death situations, and, in turn, impact the behavior of trained combat units. Tracing this physiological blueprint for combat effectiveness, Herr realized it could be altered biologically. “All of sudden the Matrix made sense,” Herr says, referencing the secret world of the eponymous 1999 sci-fi film.

The military could select troops and their officers for their unique, inborn ability to cope with stress. Or it could directly tweak a soldier’s body functions — re-balancing the normal hormonal cocktail so the soldier doesn’t panic, doesn’t retreat and keeps on fighting, even when the odds are against him and any normal person would just give up.