The ability to talk and otherwise communicate symbolically gives our own species an unusual moral flexibility. As symbol-using creatures, we can discover new information, assess and reconsider it, and in that fashion the moral conversation continues. Such is the hope of human history: that we can progress into a more finely-tuned sense of ourselves. The power of language alone can explain the unusual flexibility of human morality, but language is not the only route through which moral flexibility appears.
Flexibility also emerges through the normal workings of variety. In human societies, we see significant cultural variety. True, the underlying emotions responsible for moral systems are the same across cultures, but we also produce cultural variants of those systems. And since the moral rules are established and supported not by all individuals equally, but rather more fully by more socially-powerful individuals, we find a secondary source of variety produced by the varying personalities of our leaders. It does matter, after all, whether your society is led by Winston Churchill or Adoph Hitler.
A similar pattern can be found in other species.
"It is amazing what a difference the personality of the alpha male can make in the relationship dynamics of an entire group," writes primatologist Susan Perry in Manipulative Monkeys (2008), describing the white-faced capuchins she has studied in the forests of Lomas Barbudal, Costa Rica.
Perry recalls that scar-faced, ever-snarling old fellow named Curmudgeon. As alpha male, Curmudgeon was "the obvious favorite" of all the females. Wherever this tough monkey went, he was followed by a procession of "excited fans," who made a friendly gargling noise as they approached and reached out, trying "to touch their idol"--while Curmudgeon contributed to the effect with his hair-raised swagger and lordly airs. He was "unquestionably the most self-confident alpha male I had ever known," Perry writes, and he always seemed to have a powerful sense of his own drama. Whenever he urinated, for example, Curmudgeon "arched his back, fluffed up his hair, made a resonant rhythmic grunting sound, and splashed urine all over his hands and the monkeys in the vicinity. None of the other monkeys looked anywhere near as important when they urinated."
Curmudgeon's leadership style was typical for alpha-male capuchins: tyrannical. Most of them are "control freaks, constantly monitoring, commenting on, and manipulating the relationships of the subordinate males in their group."
Yet Pablo, who was the alpha of another social group in the same forest showed a remarkably different personality. Pablo was a laid-back sort who seemed unfazed by friendly interactions among his subordinates. In Pablo's community, males frequently groomed one another, and he himself was an unusually active groomer.
In short, Pablo was a different leader with a different personality. The result? Perhaps most remarkably, Pablo would allow sexual contact between the subordinate males of his community. Male homosexuality was definitely a no-no in the other social groups of Lomas Barbudal.
Whenever she switched from watching Curmudgeon's group to Pablo's, Perry felt she was "entering a different culture." Because Pablo was so relaxed with his male subordinates, they seemed comfortable in their mutual associations, and that in turn meant they were "highly cooperative" and "able to form a united front against enemy males that is frighteningly effective." Meanwhile, and possibly because they were so tightly-bonded, the males in Pablo's group would occasionally coerce females sexually, which was virtually never seen in the other capuchin groups.
Since the temperament of leaders can vary, then to some degree we can seek in that variety the potential for social and moral flexibility. Change the strutting character in charge, and to some degree, you might change the character of a society.
Yet changing the individual in charge is not easy. Powerful individuals rely on the psychological inclination of others to submit to their authority, and they also rely on social enforcements to hold onto it. Social enforcements: acts of intimidation, distributions of favors, strengthening of alliances, expressions of loyalty, laws prohibiting treason and an army sworn to loyalty.
Animals don't have written laws prohibiting treason, obviously, but they may well attend to important alliances or promote significant expressions of loyalty. Among the white-faced capuchins of Lomas Barbudal, males do some strange things that may serve to reinforce friendships and political alliances. They suck lingeringly on each others' ears, tails, and fingers, for example. But possibly the oddest ritual of all is eyeball poking, where one monkey draws another's hand up to his own eye, then guides the other's fingernail and finger gently into the eyesocket behind the eyeball. Mutual eyeball-poking sessions among these monkeys last up to an hour, and they mean . . . what? Perry believes it could serve to communicate mutual trust. An eyeball is supremely vulnerable to damage and infection, so encouraging someone else to reach a fingernail and finger behind it is a bold act demonstrating great trust.
(Olive baboon males in Africa do something roughly comparable when coalition partners greet by grasping each other's testicles. This mutual testicle-holding, with one bloke placing his entire reproductive future in the hands of another, expresses most emphatically a mutual trust. One can only imagine, if these baboons had language, the compelling poetry of their oaths: "By my very balls, I pledge. . . .")
Yet loyalty has limits, and oaths will be broken. No leader can survive forever, and without a formalized, written method for changing authority, the powerful are often doomed to endure the informal and unwritten means of social change, such as assassination, mutiny, or coup d'état--as Curmudgeon abruptly discovered one day.
After a brief absence, Susan Perry returned to the forest to find Curmudgeon alone, injured, and emitting a pathetic series of I-am-lost calls. His voice, Perry writes, "cracked and trembled, each syllable ending with a whiny whimper, in stark contrast to the confident, steady quality his voice had had before." She had never before seen him alone. She had only once seen him injured. Now there was a deep gash on the bottom of one foot, another on one shoulder, puncture wounds elsewhere. Unable to use his legs, the former alpha moved by dragging himself with his arms up trees and across branches. His hair was flattened, making him appear "deflated" in comparison to his previous hair-raised confidence, and altogether he looked "miserable and terrified." Curmudgeon had been displaced by a new alpha male, who must, Perry believed, have been supported by his own group of plotting allies. No single monkey, working alone, could have done such damage. Poor Curmudgeon!