[Geneticist Danny Brower] explained that with full self-awareness and inter-subjectivity would also come awareness of death and mortality. Thus, far from being useful, the resulting overwhelming fear would be a dead-end evolutionary barrier, curbing activities and cognitive functions necessary for survival and reproductive fitness. […] In his view, the only way these properties could become positively selected was if they emerged simultaneously with neural mechanisms for denying mortality.
If this logic is correct, many warm-blooded species may have previously achieved complete self-awareness and inter-subjectivity, but then failed to survive because of the extremely negative immediate consequences. Perhaps we should be looking for the mechanisms (or loss of mechanisms) that allow us to delude ourselves and others about reality, even while realizing that both we and others are capable of such delusions and false beliefs.
We humans are an odd lot.
From Nature’s Correspondance section, “Human uniqueness and the denial of death”, August 5, 2009. doi:10.1038/460684c;