I understand your original point was about a neural structure involved in humanization, and not of facial recognition, but am responding to the point you let the interlocutor derail this to.

> > "We haven't yet found a specific neural structure for recognizing faces" is far from evidence that no such structure exists.

> proving a negative is, famously, quite hard.

Whether structure or not, we do have very strong evidence that a mechanism of facial recognition exists as there are people who lack this mechanism to various degrees.

This article posits that we have indeed discovered a specific neural structure involved in facial recognition: https://www.aipc.net.au/articles/the-neuroscience-of-facial-...

> The brain has even evolved a dedicated area in the neural landscape, the fusiform face area or FFA (Kanwisher et al, 1997), to specialise in facial recognition. This is part of a complex visual system that can determine a surprising number of things about another person.