Last Ape Standing: The Seven-Million-Year Story of How and Why We Survived

by Chip Walter

  The primal depths to which our sense of morality runs, and the murkiness of what we consider to be a moral or an immoral act, were brilliantly illuminated in a thought experiment that British philosopher Philippa Foot conceived over thirty years ago. (American philosophers Judith Jarvis Thomson, Peter Unger, and Frances Kamm later expanded upon Foot’s experiment.) It asks that you imagine you are standing on a bridge overlooking tracks down which an out–of–control train is hurtling. As your eyes follow the route of the train, you are horrified to find five people tied to the track. But, you are told, you can save the five doomed people if you flip a switch that will direct the train toward a second fork. The only problem is that there is also another single person bound to those tracks.

  Now what do you do?

  The vast majority of those who take this test, or variations of it, don’t hesitate to say they would flip the switch and sacrifice one person to save five. It’s not a perfect situation, but at least, the thinking usually goes, five people are being saved even if one must be sacrificed to spare them. (What would you do?) Several years later, Judith Jarvis Thomson raised the experiment’s stakes by offering an alternative scenario. This time the train is headed toward our doomed fivesome, but the only way you can save them is by throwing a heavy object in front of the oncoming train. As it happens a large person is standing with you on the bridge. Should you push the person over the railing to save the same five people? Could you?

  Deciding what to do in that second situation turns out to be a lot more difficult than in the original scenario. But why? The outcome is precisely the same: one human life sacrificed to save five. But this time it’s personal. It’s one thing to flip a switch; the logic is obvious and you can act by remote control. But it’s quite another thing to look a fellow human in the eyes and then personally push him to his death below. Not that most people think all of these issues through coolly and logically before they answer. The reaction is visceral, primal.

  If we see the rudiments of morality in examples such as these, it’s not difficult to imagine how primeval versions developed among the tribes of early humans who had begun a million years ago to make their way out of Africa and take the human species, for the first time, global.

  In many ways their situation was similar to another classic thought experiment that emerged in the 1950s out of what computer scientists call game theory. The problem is called the Prisoner’s Dilemma and is based on the work of two mathematicians, Merrill Flood and Melvin Dresher, at the RAND Corporation. (Much later Albert W. Tucker added some formal touches to the game.) As much as we might like to think that our sense of fair play traces its roots to human kindness and altruism, game theory illustrates that deep down even the best behaviors stand on a practical foundation, a form of enlightened self–interest, at best. For our purposes the game goes like this.

  Jack and Joe are arrested by the police and charged with robbing a bank. It’s a given that both men are pretty reprehensible and more concerned about their personal freedom than they are about one another. The problem is the authorities don’t have sufficient evidence to convict either one. So they separate them and offer each an identical deal: You can testify against your partner, and if he doesn’t testify against you, you’ll go free and he’ll go to jail for ten years. If you both remain silent, then you’ll each serve a short sentence. If you both testify against one another, you will each serve five years. And if you refuse to testify at all, but your partner testifies against you, you will serve the full sentence. (It’s a fair bet, by the way, that the British police investigating the Iddon murder used exactly this strategy with the murderers, several of whom did eventually turn on their fellow conspirators.)

  Scientists have found that if the game is played once, six players out of ten choose to testify against their partner. We shouldn’t be too surprised that most people will rat out their partner because by testifying this one time, the best thing that happens is you walk away. The worst is that you end up with a split sentence.

  If the game is played again and again, however, and the players can exact revenge on one another or reward good behavior, which is more the way life is, then the players gain enough feedback that they learn how their counterparts behave, and in time something interesting happens. Each player begins to cooperate with the other because each realizes that watching out only for himself (and choosing to turn in his partner) may result in his partner’s punishing him the next round of the game. What happens? They both begin to choose to not testify, which results in both getting off with a slap on the wrist. A sort of morality emerges. Players begin to realize that if they treat others as they would like to be treated—the Golden Rule—life won’t be perfect, but it will, on balance, be pretty good.

  What all of this clearly reveals is that we are, and have been for some time, moral animals. But where does our morality come from? Why did it even evolve? Other animals (with the exception of some of our cousin primates) don’t struggle with morality. Why should we?

  The reason is because we are so shamelessly social.

  By the end of 2011, Facebook, the current darling of the Internet, claimed 750 million active subscribers, who together pass an average of 700 billion minutes a month digitally engaged with one another. Since its emergence in 1993, the World Wide Web has rocketed from zero Web sites to 45 million, and counting. Last year, uncounted billions of us worldwide were busily talking, incessantly texting, or otherwise interacting with one another on more than five billion cell phones. These statistics aren’t simply impressive examples of our ingenuity; they represent monuments to our primal need to connect with one another.

  The convivial interactions of ants, termites, and certain kinds of algae not withstanding, we humans are indisputably the most socially complex species to have ever emerged on planet earth. We cannot bear to be disconnected. For a human, the worst kind of torture is solitary confinement, a punishment that can lead to depression, hallucinations, and madness. We can’t seem to help keeping constantly in touch, literally or metaphorically, always reaching out, laughing, crying, gossiping; talking at, with, or about; watching, gaping, glancing; listening in, listening to. Even in ignoring one another we are tacitly bonding by acknowledging that others are around us to turn our nose up at. Ugly as they are, hatred, jealousy, envy, rage, discrimination, even murder, could not exist if we weren’t, first and above all, bound to one another inextricably. It is possible, I suppose, that in some parallel universe each of us could be like Dickens’s Ebenezer Scrooge, “as solitary as an oyster,” but if that was the case, not only would love, marriage, business, and cities be out of the question, so would Super Bowls, World Cups, global trade, finance, symphonies, and the rest of human civilization with them. We have built the world that we have built, either in cooperation or competition with one another, but we have built it.

  The currency of our connectedness is communication, which is so mystifying that legions of scientists still labor ceaselessly to unravel its complexities. We communicate using language, but also by tapping uncounted libraries of nonverbal behaviors, too—laughter, tears, body language, and facial expressions, not to mention painting, mathematics, sculpture, music, and dance in all of their variability across all the cultures of today, yesterday, and futures to come. Each of them represents a handful of the unending inventions we press into service to express to one another what we are thinking, feeling, exploring, want or wish for, fear, hate, and love.

  All of life is linked, from amoebic protozoa to the invisible oxygen–fixing microbes that make the enormity of sequoia trees possible. We aren’t alone in that. Of the one hundred quadrillion cells that each of us carries through the day, for example, only 10 percent belong to us. The rest are outsiders, the microbial flora and fauna that live in our stomachs and organs and dine out on the surfaces of our bodies. Yet without those trillions of hardworking microbial committees, not a single one of us could make it through the day. We need one another.

  Global ecosys
tems likewise require connection and communication. Symbiosis and competition make the world, quite literally, go around, because without the interactions of life, from the oceans’ microscopic phytoplankton to rumbling migrations of wildebeests, our world might just as easily be as dead, phlegmatic, and torridly hot as Venus, or as cold and parched as Mars. In short, life and communication can’t be separated. But in our case the affliction is unusually deep and complex.

  We can trace these tendencies back to the early mammals that began to gather evolutionary momentum after the dinosaurs were wiped out sixty–five million years ago. A cerebral innovation that mammals brought into the world was the brain’s limbic system, the seat of our emotions. Lots of mammals are social and live in packs, prides, and herds, but our particular primate line traces its roots to mammals that evolved into monkeylike creatures that mostly stuck to the jungle, but also eventually ranged out into the savanna, where they lived in small clusters.

  From these, and in a relative blink, multiple species of primates arose between twenty-five and five million years ago. Since every other human species that has ever managed to make its way into existence is now extinct, except for us, our closest living primate relatives are chimpanzees, bonobos, and gorillas, all of them exceedingly sociable. This tells us that when our earliest human ancestors found themselves stranded on Africa’s expanding savannas, they were already inveterately communal. After all, shortly beforehand they all shared a common ancestor.

  The best we can figure, they lived in troops of twenty to fifty, possibly more, sometimes less, traveled together, shared food, fears, sex, and other dangers and amusements. So tight were their communities that there would have been zero chance of any member of the troop running into another and not recognizing him or her immediately. (Maybe this is why studies reveal we have trouble handling more than twelve to fifteen truly personal relationships, Facebook notwithstanding.) The only strangers these creatures would have encountered would have hailed from other troops or even other species, and those encounters would likely have been as strange as you or me running into a Sioux warrior from 1825 at the local mall.

  As our ancestors were left to wonder their new, more dangerous grassland environment, the ties that bound them would have grown tighter than ever. The aphorisms “misery loves company” and “there is safety in numbers” might arguably have found their origins here. On the savanna there were more predators, but fewer places to hide, less food, less water, than the jungle provided, even more competition from other troops given the dearth of resources in their new home. Disease and injury surely did in more than one man, woman, or child as the troop wandered from place to place among the volcanoes, and along the shores of lakes like Turkana, every loss threatening to rub the clan down to a size that made it impossible to survive the next disease or environmental blow.

  Now add to all of this the pressures early–born children brought to the mix. You find yourself awakening every day bound to your fellow creatures working to survive, raising children, forging friendships and alliances, scrounging for food, and communicating as much as your brain and body will allow. You have no other choice because if you don’t, you will die. But (there is always a but) living in such a tight community also means competing with the selfsame creatures you rely upon for mates and status and resources. Tricky situation, because it requires balancing what you want for yourself with everyone else’s needs. It means simultaneously taking care of number one and watching out for those around you. This is the central paradox of the human condition—balancing, constantly, two seemingly opposite needs.

  We see the evidence of this continuing dilemma every day from sibling rivalries to office politics, from international trade to military balances of power. Every day’s headlines and news reports are dramatic testaments to our struggles to act morally. Robbery, terrorism, murder, heroism, stock–market crashes, war, charity, law, international aid, trade, and political intrigue are all examples of our attempts, and failures, to deal fairly and ethically with one another, writ large. For the bands of our predecessors struggling to survive on Africa’s plains, however, this was new territory, and it required the development of some kind of moral code.

  Think back for a minute on the Prisoner’s Dilemma. Existence on the savanna among small troops of hominins would have been remarkably similar to Jack and Joe’s situation after their arrest. If you were a member of the troop, it would make no sense to repeatedly abuse those around you even if you had the power to do it. If you did, you would quickly find yourself persona non grata, shunned by the troop, or, worse, dead.1

  On the other hand, what about your needs? You ignore those at your peril, too. You require a mate, food, safety, and personal power just as much as anyone else. To deny these could result in your death, too. A dicey dilemma.

  We are clearly and painfully still struggling with these issues, but over the long haul evolutionary forces encouraged our ancestors to cooperate enough with one another that they managed to make it to the twenty-first century. Like Jack and Joe, experience taught our ancestors that on balance cooperators tended to stay alive long enough to have babies and pass their genes along. Cooperators wouldn’t have always gotten everything their way, but they also wouldn’t have been tossed out of the group to fend for themselves, a sure death sentence given the harsh realities of life a million years ago. Success in such a tight community depended increasingly upon how deftly you navigated and balanced your relationships with your peers. Accomplishing that, however, required an even more powerful brain than the one nature had already bestowed on struggling predecessors.

  In the 1990s a Liverpudlian psychologist named Robin Dunbar conducted research that illustrated a correlation between the size of an ape’s brain and the size of the troop in which he lived. The larger the group, the larger the brain. He argued that bigger troops drove the evolution of larger brains because every new addition to the group ratcheted up the number of direct and indirect relationships each member had to keep track of. Juggling more relationships required a corresponding boost in intelligence. Evolution would have favored smarter, larger–brained members of the troop because they would have been better equipped to track the growing social relationships between fellow primates.2

  Something similar was happening among our direct ancestors on the plains of Africa a million years ago, with an important additional ingredient. The driving force behind the evolutionary change wasn’t merely the size of the group; it was the complexity of the relationships inside it. Our ancestors were much smarter than Dunbar’s primates, and the dynamics of their relationships would have been more complicated. After all, at that time they were the smartest creatures on earth. Greater intelligence is a multiplier of complexity because it increases the number of factors in relationships. It adds more variability, more motives, more intrigue and nuance, and, in turn, drives up the advantages of possessing the additional neuronal firepower needed to constantly calibrate exactly why people are acting the way they are, and more particularly why they are acting toward you the way they are.

  Human relationships are dynamic and fluid. They change constantly. Rarely do we unquestionably love, or entirely distrust, the people in our lives. Mostly our relationships slide along a continuum in a never–ending exchange of interpersonal, emotional, and mental calculations. The social lives of our ancestors may not have reached the Machiavellian proportions of the Soviet politburo, the court intrigues of Henry VIII, or even the office politics of Mad Men, but, generation by generation, you can be sure they were getting increasingly complicated. And that would have required the introduction of a new and powerful behavior: deception. Or more precisely, as you will see, our ability to detect deception.

  At this point in the evolution of life on earth, deception was clearly far from new. Prevarication is an essential part of existence and has been for far longer than our kind has been around. Venus flytraps pose as beautiful flowers to lure their quarry to their doom. A leopard’s spots or a chameleon�
��s changing colors dupe prey and predator alike. Young spider monkeys have been known to fake predator calls so they can scatter their elders who are dining on recently found food, then pilfer the goods before others in the troop are any the wiser. The cake for natural deception might have to go to a particular shallow–water anglerfish (there are many species) that looks remarkably similar to a rock encrusted with sponges and algae. At the end of its head extends a thin spine that supports a piece of itself that would be the envy of every avid reader of Field & Stream magazine. It looks exactly like a small living creature right down to the pigment along its flanks and “eyes” at the top of its faux head. The anglerfish even wiggles the bait so that it seems to be swimming along just like any number of other fish in the sea. When a hungry fellow fish arrives to take the bait, the angler gulps it down before it has even realized it is the hunted, and not the hunter.

  There is, however, a difference between these deceptions and the human variety. The human sort that was shaping up a million years ago was conscious, which is to say planned and driven not purely by genetics. In these ancestors we begin to see the evolution of chicanery in the service of self–interest at a level never before seen, the deliberate, premeditated variety.

  In some ways cheating of this sort was inevitable. It is the flip side of the primal moral code that was evolving at the same time. As early humans found ways to cooperate and trust one another—which was absolutely necessary if they hoped to survive—wasn’t it equally inevitable that deception would also emerge? It was, after all, a powerful way to serve personal ends without having to deal with the overt danger of direct confrontation inside the troop—a perfectly understandable, even brilliant, adaptation when you consider the circumstances. Deception was an accommodation, a kind of compromise, except that only one party was in on the secret. If you can cheat and get away with it, you’re riding on the backs of others to your benefit (and their detriment) without anyone’s knowing it or becoming even the slightest bit upset about it. Not a bad ploy, if you can get away with it.