Being Human
By examining our shared biology with other species, we reveal that what makes us human is not a separate essence but the extraordinary and unprecedented ways we use the same ancient tools.
Source: https://www.youtube.com/watch?v=TnlZwfD-GiU
The venue encouraged drinking, and the street outside was eerie. For Robert Sapolsky, a neurobiologist and primatologist accustomed to studying baboons in Kenya, this setting made him feel like more of a hipster than ever before. But the real displacement comes from his dual perspective. Spending half his life in a lab manipulating neurons and genes, and the other half observing primate social dynamics, he eventually begins to look at Homo sapiens quite strangely. He finds himself wondering not just about people’s neurotransmitter levels, but also whether their canine teeth are longer than his own, or calculating how much anesthetic would be needed to dart them. This peculiar vantage point leads to a central, profound question: Are we just another primate? Are we merely a collection of neurons? Where do we fit in the biological world?
The answer, Sapolsky suggests, is that we keep being just like every other species until you look a little closer. Understanding humanity requires navigating three distinct domains. The first involves recognizing where our biology is nothing fancy—we are operating with the same basic mechanisms as countless other animals. The second domain is where we possess the same neurological wiring as other species but deploy it in utterly bizarre circumstances. Finally, there is a third domain where human behavior is simply unprecedented, with no true animal parallel.
The Familiar Blueprint: Just Another Animal
Consider the female hamster. Her existence is governed by a simple biological clock: she ovulates approximately every five days. This cycle can be synchronized with another female hamster sharing her cage. Through olfactory pheromones, they align their cycles to the same afternoon within about three weeks. Block the hamster’s nose, and synchronization fails. Insert a male hamster into the cage, and their cycles desynchronize completely—a phenomenon achievable simply by pumping air from the male’s cage into theirs. Most remarkably, synchronization is not random. The socially dominant female tends to synchronize the other. This is well-understood biology, with commercial applications like pig ovulatory synchronization spray.
And it was once thought to work identically in humans. The “Wellesley effect,” named after a 1970 paper from the all-women’s college, suggested that female roommates would synchronize their menstrual cycles during their freshman year, driven by the same pheromonal communication. Unless, that is, one roommate was in a close relationship with a male, which would desynchronize them. The social hierarchy within the pair was also thought to play a role, with the more extroverted, dominant woman dictating the synchronization. In settings like this, the challenge is accepting our fundamental similarity to other species. Our biology runs on ancient, shared scripts.
The Same Wiring, Used in Bizarre Ways
In the second domain, we see the same physiological systems activated for entirely novel purposes. Picture two humans sitting in silence at a table, not even making eye contact. Every few minutes, one might lift an arm to move a piece of wood. If these are chess grandmasters in a tournament, they are maintaining, purely through thought, the blood pressure of marathon runners for hours on end. This is the quintessential human twist: we activate the same ancient stress responses for abstract, psychological threats. We secrete the same cortisol and adrenaline that a fish or reptile does when facing a predator, but our trigger is worrying about the ozone layer, a looming deadline, or a social slight. The neural hardware is conserved; the software running on it is astonishingly new.
This extends to our capacity for violence. While many species kill conspecifics—chimpanzees have been observed fashioning weapons and conducting organized border patrols that amount to genocide, and baboons like those Sapolsky studies have high rates of male-male homicide—the ways in which humans are violent are uniquely complex. We can kill with no more effort than pulling a trigger, dropping a bomb from 30,000 feet, or operating a drone from another continent. We can commit violence through passive aggression, by looking the other way, or through damning with faint praise. Most chillingly, we can aestheticize it. The writer VS Naipaul, traveling through Indonesia decades after the mid-1960s coup that killed an estimated half a million people, heard accounts of death squads bringing along traditional gamelon orchestras. When he asked an unrepentant veteran why, the man’s answer was simple and profound: “To make it more beautiful.” No other primate can comprehend that.
Our social cognition follows a similar pattern. Young children typically develop a theory of mind—the understanding that others have different information—between ages three and five. But we are not alone in this. Chimps can demonstrate it, understanding that a human with a bucket over their head doesn’t know where food is hidden. What is uniquely human is secondary theory of mind: the understanding that this person knows what that person thinks, and using that to navigate complex social webs. This is why no chimp could follow the plot of A Midsummer Night’s Dream, where characters are in love with others who are in love with yet others under a magical spell.
The Universality and Complexity of Reciprocity
The golden rule—do unto others—is a cornerstone of human morality and appears in every society. Game theory, the mathematical study of strategic interaction, has formalized this through the prisoner’s dilemma. In the 1970s, economist Robert Axelrod invited strategists, theologians, and others to submit algorithms for this game, where two players can either cooperate or defect. He then ran hundreds of thousands of simulated tournaments. The winning strategy was the simplest one: tit for tat. Start by cooperating, then mirror your opponent’s previous move. This strategy proved evolutionarily stable, driving others to extinction.
Animal behaviorists wondered: do other species use this optimal rule? The answer is yes. Vampire bats, which feed their young with regurgitated blood, engage in reciprocal feeding. If a female is caught hoarding blood and not sharing, others will refuse to feed her babies in the next round. Even stickleback fish demonstrate tit for tat in territorial disputes using mirrors. So, what is uniquely human? Our ability to practice reciprocity with a currency that is not the same for everyone. We understand that others have different desires and reinforcers. We can tailor our cooperation to an individual’s unique motivations, creating a vastly more complex world of social exchange.
Empathy Across Boundaries
Empathy feels like a defining human trait, yet we are not the only species with a sense of it. Primatologist Frans de Waal showed that chimpanzees are more likely to console a victim of unprovoked aggression than one who initiated a fight, demonstrating an understanding of intent and fairness. We are not the only ones who can feel for an underdog. Where we are exceptional is in the reach of our empathy. We can extend it across species, feeling the pain of a dog caught in a trap. We can extend it to the abstract and fictional. We can feel for a purple, terrified, non-existent animal in a Franz Marc painting titled The Fate of the Animals. We can weep for the fate of the Na’vi in Avatar, knowing they are merely pixels, or for the characters in a novel. Our empathy can be activated by symbols, stories, and imagined scenarios, a leap of abstraction no other species can match.
The Long Wait: Dopamine and Delayed Gratification
The neurotransmitter dopamine is central to reward, but its true function is more subtle. It is not about the reward itself, but the anticipation of reward and the motivation to work for it. In classic experiments, a monkey secretes dopamine not when it gets a grape, but when a signal light comes on indicating the opportunity to work for one. Even more powerfully, dopamine surges when the reward is only delivered about 50% of the time. The introduction of “maybe” supercharges goal-directed behavior, the same neurochemical principle that powers the allure of Las Vegas.
Humans operate on this same system, but with an extraordinary temporal extension. We can have a lag time between the signal, the work, and the reward that lasts a lifetime. We study hard for good grades, to get into a good college, for a good career, all for a reward decades in the future. Most astonishingly, humans will “lever press like mad” for a reward that doesn’t arrive until after they are dead, if their theological or ideological framework provides the right incentive. The capacity for this temporal abstraction of reward is unparalleled in the animal kingdom.
The Unprecedented: The Byways of Culture and Contradiction
Culture, once a taboo word in primatology, is now recognized in other species. Chimps learn complex tool-use traditions from their mothers, and daughter-chimps are better apprentices than sons. Sapolsky’s own work documented a troop of baboons that developed a uniquely peaceful culture with high levels of male affiliation, a social norm that new males joining the troop learned to adopt within months. We are not the only species with material or social culture. What is unique is its Byzantine complexity—the layers of ritual, symbolism, and social nuance that no chimp could ever devise.
Finally, Sapolsky points to a domain of human behavior that is truly in a category of one: our ability to derive strength from the impossible. He frames it abstractly: “We have the capacity to gain the strength to do X by the certainty that X cannot possibly be.” This is not mere optimism. He illustrates it with Sister Helen Prejean, the death row chaplain. Her life’s work is built on two paradoxical tenets: “The less forgivable the act, the more we have to find the means to forgive it. The less lovable the person, the more we have to find the means to love them.” To Sapolsky, a strident atheist, this is “the nuttiest, most irrational, magnificent thing we are capable of as a species.” Our most exalted moral behaviors—perseverance in the face of hopelessness, radical forgiveness, love for the seemingly unlovable—are often fueled not by a realistic expectation of success, but by a defiant commitment to the value of the act itself. It is in these moments, when we act despite the certainty that we cannot make a difference, that we reach the summit of our humanity.
In the end, we share the neurochemistry of the ape, the social strategies of the bat, and the primal drives of the primate. But we deploy them to build empires, write symphonies, wage wars over ideas, and love across unbridgeable divides. We are just another animal, until we are not.
This article is adapted from a YouTube talk by Robert Sapolsky.