It's also based on Jane Goodall's high level of anthropomorphizing chimps, on New Age old philosopher favorite Rudolf Otto, and personalized definitions that would probably get flunked out of a class in either philosophy of religion or ethology, and probably in anthropology of religion, too, which is what James Harrod claims is his ... yes, I'll go there, his "ground of being."
The problem is that, just as with evolutionary psychology, let alone Pop Ev Psych, even if human brains fossilized more than they do, human behavior doesn't. Also, the rate of genetic change isn't constant, and we can't readily tell when it "hiccups." This all, also, ignores environmental influences as well as the lesser, but not nonexistent, influence of epigenetics and other para-genetic issues.
The third is that Harrod's dialetical-like pairing of opposing behaviors as a theoretical foundation seems tenuous.
The fourth is that he shifts from "fear of death" to Rudolf Otto's idea of the numinous, the mysterium tremendum and mysterium fascinans. (And, no, the "holy" etc., will not be capitalized on this site.)
We don't know whether or not a fear of death became "numinous" even if Otto's ideas hold a lot of water. Nor, per my comments above, do we know whether or not, even if a fear of death became numinous to early humans, it was the most numinous idea in their metaphysical constellation.
Harrod wrestles not one iota with any of these issues.
The fourth is that he relies heavily on Jane Goodall, including ingesting wholesale her degree of anthropomorphism, along with other things for which she has been criticized.
Related to this is that the author doesn't do much of an explainer as to where he got his "trans-specific definition of religion" from, or why. An initial glance of his list on pages 24-25, though, suggests extensive cribbing from Rudolf Otto and "The Idea of the Holy." Well, that's Harrod's own cribbing, then. I don't know what exists within the world of philosophy of religion in terms of discussion of "trans-specific definition of religion," but I'm pretty sure Rudolf Otto isn't the starting point. Certainly, "awe" is not a specifically religious emotion. And, Harrod admits near the end that this is pretty much a personalized definition, based largely on Goodall, who apparently has swallowed Rudolf Otto wholesale.
The fifth is that what may or may not constitute religion under a working definition of anthropology of religion is very latitudinarian. Going by this, rather than the properly done evolutionary psychology of Pascal Boyer or Scott Atran, is like trying to nail Jell-O to a wall.
But wait, that's not all!
Nine? This gets to the New Age in the header. Harrod gets more mystical yet, even looking for the classical four elements of earth, air, water and fire that chimps venerate. So, actually, he's mashing up Otto, Goodall, and Thales, Empedocles, Heraclitus and Anaximander of pre-Socratic fame.
So, in short, pass. Totally pass, at least on Harrod.