We come from a long lineage of hierarchical animals for which life in groups is not an option but a survival strategy. Any zoologist would classify our species as obligatorily gregarious.
— Frans de Waal, Primates and Philosophers: How Morality Evolved, pg. 4
Obligatorily gregarious is a fancy way of saying that humans are required to be sociable. Unlike any other apex (top of the food chain) predator, we aren’t born with functional weaponry. Alone and unarmed, we’re no match for many animals despite our intelligence. Even armed (with anything short of missile weaponry, at least), a lone human would be prey for other social animals (like wolves, lions, and orca) if evolution hadn’t “taught” them to be wary of humans.
Being social and cooperating allows economies of scale and the tackling of tasks too large for a single individual (like bringing down large prey). Having companions means having someone to take up the slack and provide care when one is sick or injured. Being social provides many evolutionary advantages with the sole major disadvantage being the amount of space and other resources required to feed a group as opposed to an individual (which is why some apex predators like bears and pumas have large ranges and are generally more territorial than sociable).
Being accepted by others was the most important survival trait for most of mankind’s history and it retains most, if not all, of that importance today. For us, especially today, the most salient feature of the “immediate, local environment” that drives evolution is the society that we are embedded within. Navigate that environment well and turn it to your advantage and you will survive and thrive. Ignore it or fight against it and you will miss endless opportunities (and probably bring endless trouble down on your head).
Given this environment, moral appearances add tremendously to evolutionary “fitness”. Even altruism, despite many über rationalists’ claims, dramatically increases the odds of living well and passing on your genes. First, perceived altruists are given more freedom and latitude to act than people who are perceived as not being interested in the welfare of others. Second, perceived altruists are far more likely to receive help when it is necessary and benefits and gifts when it is not. Finally, obvious altruism certainly acts as a “fitness display” similar to a peacock’s tail. There are no guarantees of any of these things (and the true altruist shouldn’t be seeking them out) but given the way that things normally work out, altruism is certainly more rational than obvious greediness and/or miserliness.
Unfortunately, it is the maintenance of a moral reputation rather than being moral itself that is the immediate cause of evolutionary fitness. If an individual can “cheat” without his reputation being harmed, it is evolutionarily advantageous to do so. On the other hand, being “cheated” is evolutionarily disadvantageous so we are constantly evolving “cheat detection” abilities and systems that make cheating riskier and less advantageous while cheaters counter with new and better methods of cheating and hiding their cheating. This leads to an “arms race” or a so-called “Red Queen race” (after Alice in Wonderland) where tremendous effort is spent solely to remain in place.
One of the oddest results of this arms race is the separation of the mind into a “conscious” mind which does all of our logical reasoning and communication and a “subconscious” which performs all of our decision-making and moral judgments without the details and inner workings being accessible to our conscious mind. This architecture allows the conscious mind to believe that decisions and actions had a reasonable moral basis even when the true subconscious motives were nothing of the sort. This ability to self-deceive evolved to better mask deception from those who perceive it well — enabling, as Robert Trivers puts it, “Hiding the truth from yourself to hide it more deeply from others.” Similarly, other people argue that one of the primary reasons why language evolved was so that we could justify ourselves to others.
One would think that the ability for the conscious mind to review and correct the thinking of the subconscious would be a tremendous boon so the fact that the ability to self-deceive apparently out-competed it indicates that the need to appear moral/social is indeed a powerful force. For very similar reasons, powerful emotions are also invoked when morality is involved. The facts that unconscious reasoning is inaccessible to the conscious mind, that the unconscious mind is eager and able to bias the conscious mind’s reasoning without it normally being noticeable, and that emotions can block any rational discussion makes morality a difficult subject to tease apart. Yet, tremendous benefits could be gained if we are able to bring the full power of our intelligence to bear on what is arguably the source of our most dangerous problems.