I do not know Dr. Z, but his premise here is oversimplistic and fatally flawed, I believe:

The primitive tribe, in the woods and hunting, gathering nuts or tubers, cannot constantly think about an impending attack by a carnivore, else would be debilitated and unable to function.

The argument here seems to be that, in order to go about their daily affairs, primitive peoples must ignore (ie, deny) the threat posed by carnivores.

I think it is much more likely that primitive peoples are highly aware of the threat, and take precautions to reduce their vulnerability so that the dangers posed by external threats such as carnivores are minimized.

Crows, among other species, post lookouts while the rest of the flock forage for food. Common sense alone, to say nothing of experience, should tell us that it is not beyond the human capacity to keep one eye peeled for danger while grubbing for food, heeding the call of nature, or whatever.

I think it is quite likely that man has been a social animal since his earliest days. Women and men banded together because there is strength, comfort, and efficiency in numbers. In all tribes, there is division of labor. The concept of posting guards, or sentinels, must be an ancient one. Several men armed with spears would sit astride likely avenues of attack by predators and/or enemies, while the rest of the tribe went about its affairs.

Therefore, I think it is fair to say that the clear and present danger from external forces such as carnivores or enemies would invoke countermeasures such as sentinels and a standing guard to repel such threats, rather than a simplistic denial of the danger.

Denial is more likely to occur with events that are rare, that have never happened, or that are dismissed by "experts."

S