I clicked over to see the original diagram you show here. The author Colin Purrington may have added some labels since you originally looked at it. The labels pop up when you move your pointer over them. The root of his diagram is labeled Gullibilism. I assume that is something to do with humans evolving to the point where what they think can be manipulated by another, or can develop superstitious belief.
About as flattering as coming from a monkey's uncle I thought
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