They shared all the characteristics of humans, with the sole exception of a soul.

The human race is divided into beings animate and beings inanimate. Up to this very day, the inanimate ruled the world. The roaming, rational, resourceful, bipedal, vertebrate, mammalian, inanimate beings. They shared all the characteristics of humans, with the sole exception of a soul. We are at a turning point so critical: I wonder if one can sense, far in the offing, indistinct like the roar of a distant wind, awakening deep in the future, the rebellion, the revelation of the soul.
— Angelos Terzakis, translation, Spiros Doikas (read original in Greek)

Reading the above, decades after writing the book No Sex Please, We’re Brutish!, I realize that Terzakis echoes my thoughts. From p. 18 of the aforementioned book:

The English have no soul, they have the understatement
instead.
—George Mikes, How to be an Alien, p. 24

I discovered, however, that despite such admonitions there still remained—much to the chagrin of the people who believed in an ideal state—a considerable minority of the population who maintained some sort of an emotional, inner world. No matter how much they tried to dissimulate, emotion would emerge at the most inopportune times, obstructing the normal progress of affairs in Brutland. Ugly rumours had it that these individuals had been in possession of a soul—one of the most abhorrent miasmata that could infect a native.