This thought-provoking work of popular science contends that the human brain must have found a way to push thoughts of death aside before the species could develop into fully aware, intellectually robust beings.
That's debatable, but the authors certainly present an intriguing theory, and in mostly jargon-free prose that non-scientists can follow.
Denial's provenance, as explained in the book's introduction, is interesting on its own.
Ajit Varki, a physician and professor at the University of California, San Diego, met University of Arizona geneticist Danny Brower at a biology conference in 2005.
They had a private conversation in which Brower explained his theory about a critical point in the evolution of our species.
Varki found his own thoughts returning to the idea over the ensuing two years, and eventually decided to call Brower for further discussion.
Brower had, however, died of a rare blood vessel disease, his theory not developed into a full-length book.
Now India native Varki has finished the job, having polished and added to a manuscript Brower left behind.
The pair contend that, at some juncture early in our evolutionary saga, our ancestors had to have developed the neurological wiring for reality denial. They say it was absolutely essential.
An animal with full awareness of itself and the world around it would understand that its own death is inevitable.
The fully aware animal, say the authors, would be unable to cope and survive with the acknowledgement of mortality.
The mortality-conscious individual's behaviour would be too weird for others in its species, and it would therefore not mate -- an "evolutionary dead end," since it would produce no offspring.
To avoid this dead end, Varki and Brower contend, Homo sapiens needed to have evolved the ability to deny or repress unpleasant bits of reality. In particular, to deny the reality of mortality.
The pair defines denial as a "defence mechanism used to reduce anxiety by denying thoughts, feelings or facts that are consciously intolerable."
They say the capacity for reality denial allowed us to "become really, really smart" compared to other animals, while any individual of another species who developed full awareness would been doomed to hit the brick wall at the end of the evolutionary dead end.
Varki and Brower present (to quote Charles Darwin) "one long argument" for their speculative theory, but admit they can't "prove" it.
Even assuming that it's such a bad thing to realize one is going to die, couldn't there be other ways to avoid the dead end?
Isn't it possible, for example, that the drive to pursue pleasure and avoid pain is just so much stronger than worries about death? Or that social or community priorities, such as the support and defence of one's family or group, override mortality concerns?
But you don't have to buy into the central thesis to appreciate Denial. There's plenty more to keep the reader engaged.
Mike Stimpson is a Winnipeg freelance writer and editor.