Denial: Self-Deception, False Beliefs, and the Origins of the Human Mind
Ajit Varki Danny Brower
Twelve, 2013 ($27.00)

About 100,000 years ago something in our ancestors changed. Humans began to show new behaviors that set them apart from all other animals on the planet. Most notably, they began creating symbolic art and ornaments. For the first time, people wanted to adorn themselves and their dead, activities that suggested a newfound interest in the perceptions of others.

These artifacts may be the earliest evidence of a human theory of mind, the recognition that every individual has unique intentions, beliefs and desires. In Denial, biologists Varki and Brower (Brower died in 2007) propose a novel explanation for why humans surpassed all other species in mental prowess. The authors argue that as humans contemplated the intentions of those around them, they began reflecting more deeply on the meaning of life itself, and this examination led to the frightening awareness of their mortality. To assuage such fears, humans evolved the unique ability to deny reality. The authors reason that religion and philosophy represent some of our best efforts to do so.

A wealth of evidence documents the human talent for disregarding reality. Sometimes this ability benefits us, as when optimistic cancer patients outlive their pessimistic peers or when an athlete tricks himself into believing he has plenty of reserve energy to push his body past its limits. At other times, our self-deceptions are detrimental. According to Varki and Brower, humans are the world's ultimate risk takers, ignoring scientific facts such as the dangers of smoking and climate change.

The authors believe that this denial mechanism became essential once our brain evolved a more comprehensive understanding of ourselves and others. Before this point, they suggest, we were more like birds and elephants, possessing some—but not much—self-awareness.

Although pivotal to their thesis, Varki and Brower's claim that our fear of mortality predicated our capacity for denial remains somewhat unconvincing, in part because it is impossible to gather evidence of how we developed the relevant abilities. As they observe, there is no specific neural circuitry to explain how we evolved a theory of mind or a propensity for self-deception. It seems equally probable that these qualities co-evolved or that they are unrelated to each other.

The authors acknowledge that much of their proposal is untestable, and readers seeking conclusive answers will be disappointed. Yet Denial raises a key point regarding our contemporary concerns. Although a gift for self-deception may have saved our ancestors from despair, it might also be our downfall. But recognizing this tendency in ourselves may push us to stop ignoring unpleasant truths, such as global warming and poverty, and start addressing them.