What best distinguishes human beings from other animals is foresight.
We are misnamed. We call ourselves Homo sapiens, the "wise man", but that's more of a boast than a description. What makes us wise? What sets us apart from other animals? Various answers have been proposed - language, tools, cooperation, culture, tasting bad to predators - but none is unique to humans.
What best distinguishes our species is an ability that scientists are just beginning to appreciate: We contemplate the future. Our singular foresight created civilisation and sustains society. It usually lifts our spirits, but it's also the source of most depression and anxiety, whether we're evaluating our own lives or worrying about the nation. Other animals have springtime rituals for educating the young, but only we subject them to "commencement" speeches grandly, informing them that today is the first day of the rest of their lives.
A more apt name for our species would be Homo prospectus, because we thrive by considering our prospects. The power of prospection is what makes us wise. Looking into the future, consciously and unconsciously, is a central function of our large brain, as psychologists and neuroscientists have discovered - rather belatedly, because for the past century, most researchers have assumed that we're prisoners of the past and the present.
Behaviourists thought of animal learning as the ingraining of habit by repetition. Psychoanalysts believed that treating patients was a matter of unearthing and confronting the past. Even when cognitive psychology emerged, it focused on the past and present - on memory and perception.
But it is increasingly clear that the mind is mainly drawn to the future, not driven by the past. Behaviour, memory and perception can't be understood without appreciating the central role of prospection. We learn not by storing static records but by continually retouching memories and imagining future possibilities. Our brain sees the world not by processing every pixel in a scene but by focusing on the unexpected.
Our emotions are less reactions to the present than guides to future behaviour. Therapists are exploring new ways to treat depression now that they see it as primarily not because of past traumas and present stresses but also because of skewed visions of what lies ahead.
What makes us wise
Prospection enables us to become wise, not just from our own experiences but also by learning from others. We are social animals like no other, living and working in very large groups of strangers, because we have jointly constructed the future. Human culture - our language, our division of labour, our knowledge, our laws and technology - is possible only because we can anticipate what fellow humans will do in the distant future. We make sacrifices today to earn rewards tomorrow, whether in this life or in the afterlife promised by so many religions.
Some of our unconscious powers of prospection are shared by animals, but hardly any other creatures are capable of thinking more than a few minutes ahead. Squirrels bury nuts by instinct, not because they know winter is coming. Ants cooperate to build dwellings because they're genetically programmed to do so, not because they've agreed on a blueprint. Chimpanzees have sometimes been known to exercise short-term foresight, like the surly male at a Swedish zoo who was observed stockpiling rocks to throw at gawking humans, but they are nothing like Homo prospectus. If you're a chimp, you spend much of the day searching for your next meal. If you're a human, you can usually rely on the foresight of your supermarket's manager, or you can make a restaurant reservation for Saturday evening, thanks to a remarkably complicated feat of collaborative prospection. You and the restaurateur both imagine a future time - "Saturday" exists only as a collective fantasy - and anticipate each other's actions. You trust the restaurateur to acquire food and cook it for you. She trusts you to show up and give her money, which she will accept only because she expects her landlord to accept it in exchange for occupying his building.
The central role of prospection has emerged in recent studies of both conscious and unconscious mental processes, like one in Chicago that pinged nearly 500 adults during the day to record their immediate thoughts and moods.
If traditional psychological theory had been correct, these people would have spent a lot of time ruminating. But they actually thought about the future three times more often than the past, and even those few thoughts about a past event typically involved consideration of its future implications.
When making plans, they reported higher levels of happiness and lower levels of stress than at other times, presumably because planning turns a chaotic mass of concerns into an organised sequence. Although they sometimes feared what might go wrong, on average there were twice as many thoughts of what they hoped would happen.
While most people tend to be optimistic, those suffering from depression and anxiety have a bleak view of the future - and that, in fact, seems to be the chief cause of their problems, not their past traumas nor their view of the present. While traumas do have a lasting impact, most people actually emerge stronger afterwards. Others continue struggling because they over-predict failure and rejection. Studies have shown depressed people are distinguished from the norm by their tendency to imagine fewer positive scenarios while overestimating future risks.
They withdraw socially and become paralysed by exaggerated self-doubt. A bright and accomplished student imagines: If I flunk the next test, then I'll let everyone down and show what a failure I really am. Researchers have begun successfully testing therapies designed to break this pattern by training sufferers to envision positive outcomes (imagine passing the test) and to see future risks more realistically (think of the possibilities remaining even if you flunk the test).
Memory and the future
Most prospection occurs at the unconscious level as the brain sifts information to generate predictions. Our systems of vision and hearing, like those of animals, would be overwhelmed if we had to process every pixel in a scene or every sound around us. Perception is manageable because the brain generates its own scene, so that the world remains stable even though your eyes move three times a second. This frees the perceptual system to heed features it didn't predict, which is why you're not aware of a ticking clock unless it stops. It's also why you don't laugh when you tickle yourself: You already know what's coming next.
Behaviourists used to explain learning as the ingraining of habits by repetition and reinforcement, but their theory couldn't explain why animals were more interested in unfamiliar experiences than familiar ones. It turned out that even the behaviourists' rats, far from being creatures of habit, paid special attention to unexpected novelties because that was how they learnt to avoid punishment and win rewards.
The brain's long-term memory has often been compared to an archive, but that's not its primary purpose. Instead of faithfully recording the past, it keeps rewriting history. Recalling an event in a new context can lead to new information being inserted in the memory. Coaching of eyewitnesses can cause people to reconstruct their memory so that no trace of the original is left.
The fluidity of memory may seem like a defect, especially to a jury, but it serves a larger purpose. It's a feature, not a bug, because the point of memory is to improve our ability to face the present and the future. To exploit the past, we metabolise it by extracting and recombining relevant information to fit novel situations.
This link between memory and prospection has emerged in research showing that people with damage to the brain's medial temporal lobe lose memories of past experiences as well as the ability to construct rich and detailed simulations of the future. Similarly, studies of children's development show that they're not able to imagine future scenes until they've gained the ability to recall personal experiences, typically somewhere between the ages of three and five.
Perhaps the most remarkable evidence comes from recent brain imaging research. When recalling a past event, the hippocampus must combine three distinct pieces of information - what happened, when it happened and where it happened - that are each stored in a different part of the brain. Researchers have found that the same circuitry is activated when people imagine a novel scene. Once again, the hippocampus combines three kinds of records (what, when and where), but this time it scrambles the information to create something new.
Even when you're relaxing, your brain is continually recombining information to imagine the future, a process that researchers were surprised to discover when they scanned the brains of people doing specific tasks like mental arithmetic. Whenever there was a break in the task, there were sudden shifts to activity in the brain's "default" circuit, which is used to imagine the future or retouch the past.
This discovery explains what happens when your mind wanders during a task: It's simulating future possibilities. That's how you can respond so quickly to unexpected developments. What may feel like a primitive intuition, a gut feeling, is made possible by those previous simulations.
Suppose you get an e-mail invitation to a party from a colleague at work. You're momentarily stumped. You vaguely recall turning down a previous invitation, which makes you feel obliged to accept this one, but then you imagine having a bad time because you don't like him when he's drinking. But then you consider you've never invited him to your place, and you uneasily imagine that turning this down would make him resentful, leading to problems at work.
Methodically weighing these factors would take a lot of time and energy, but you're able to make a quick decision by using the same trick as the Google search engine when it replies to your query in less than a second. Google can instantly provide a million answers because it doesn't start from scratch. It's continually predicting what you might ask.
Your brain engages in the same sort of prospection to provide its own instant answers, which come in the form of emotions. The main purpose of emotions is to guide future behaviour and moral judgments, according to researchers in a new field called prospective psychology. Emotions enable you to empathise with others by predicting their reactions. Once you imagine how both you and your colleague will feel if you turn down his invitation, you intuitively know you'd better reply, "Sure, thanks". If Homo prospectus takes the really long view, does he become morbid? That was a longstanding assumption in psychologists' "terror management theory", which held that humans avoid thinking about the future because they fear death. The theory was explored in hundreds of experiments assigning people to think about their own deaths. One common response was to become more assertive about one's cultural values, like becoming more patriotic.
But there's precious little evidence that people actually spend much time outside the lab thinking about their deaths or managing their terror of mortality. It's certainly not what psychologists found in the study tracking Chicagoans' daily thoughts. Less than 1 per cent of their thoughts involved death, and even those were typically about other people's deaths.
Homo prospectus is too pragmatic to obsess on death for the same reason that he doesn't dwell on the past: There's nothing he can do about it. He became Homo sapiens by learning to see and shape his future, and he is wise enough to keep looking straight ahead.
Martin E.P. Seligman is a professor of psychology at the University of Pennsylvania, and one of the authors, along with Peter Railton, Roy F. Baumeister and Chandra Sripada, of Homo Prospectus, on which this essay is based. John Tierney writes the Findings science column for The New York Times.
A version of this article appeared in the print edition of The Sunday Times on May 28, 2017, with the headline 'We aren't made to live in the moment'. Print Edition | Subscribe
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