I'm looking forward to looking through that paper at the link.
Talk of ancient human brains or minds being qualitatively different from later human brains/minds always makes me a little uneasy. I'm skeptical of them being qualitatively different but rather merely being lacking in the quantity of information available to them. I may be misremembering, but I think Gilgamesh was moved by the death of Enkidu and the subsequent thinking about his own mortality that drove him to seek out the secret to immortality.
But I am curious how the paper ran its analysis and came to their conclusions.
Fascinating topic!