So it is curious to me that animals are often thought to be stuck in the present. The present is ephemeral. One moment it is here, the next it is gone. Whether you are a thrush picking up a worm for your chicks in a distant nest or a dog setting out in the morning to patrol your territory and dribble urine at strategic locations, animals have jobs to do, which imply the future. True, most of the time it is the near future, and it remains unclear how aware they are of it. Yet their behavior would make no sense if they lived entirely in the present.
We ourselves consciously reflect on the past and the future, so it was perhaps unavoidable that whether animals do or don’t would become a battleground. Isn’t consciousness what sets humans apart? Some claim that we are the only ones to actively recall the past and imagine the future, but others have been busy gathering evidence to the contrary. Since no one can prove conscious reflection without verbal reports, the debate skirts subjective experience as something that—at least for now—we can’t put our finger on. There has been genuine progress, though, in the exploration of how animals relate to the time dimension. Of all areas of evolutionary cognition, this one is perhaps the most esoteric and the hardest to get a handle on. The terminology shifts regularly, and debates are fierce. For this reason, I have visited two experts to ask them where we currently stand, which opinions will be presented at the end of this chapter.
In Search of Lost Time
Perhaps the controversy started earlier than we think, because in the 1920s an American psychologist, Edward Tolman, bravely and controversially asserted that animals are capable of more than the mindless linking between stimulus and response. He rejected the idea of them as purely incentive-driven. He dared use the term cognitive (he was famous for his studies of cognitive maps in maze-learning rats) and called animals “purposive,” guided by goals and expectations, both of which reference the future.
While Tolman—in a bow to the suffocating grip of the era’s classical behaviorism—shied away from the stronger term purposeful, his student Otto Tinklepaugh designed an experiment in which a macaque watched either a lettuce leaf or a banana being placed under a cup. As soon as the monkey was given access, she ran to the baited cup. If she found the food that she had seen being hidden, everything proceeded smoothly. But if the experimenter had replaced the banana with lettuce, the monkey only stared at the reward. She’d frantically look around, inspecting the location over and over, while angrily shrieking at the sneaky experimenter. Only after a long delay would she settle for the disappointing vegetable. From a behaviorist perspective, her attitude was bizarre since animals are supposed to merely connect behavior with rewards, any rewards. The nature of the reward shouldn’t matter. Tinklepaugh, however, demonstrated that there is more going on. Guided by a mental representation of what she had seen being hidden, the monkey had developed an expectation, the violation of which deeply upset her.2
Instead of merely preferring one behavior over another, or one cup over another, the monkey recalled a specific event. It was as if she were saying “Hey, I swear I saw them put a banana under that cup!” Such precise recall of events is known as episodic memory, which was long thought to require language, hence to be uniquely human. Animals were thought to be good at learning the general consequences of behavior without retaining any specifics. This position has become shaky, though. Let me give an example that is a bit more striking since it involves a much longer time frame than the monkey experiment.
We once applied a Menzel-type test to Socko, when he was still an adolescent chimpanzee. Through a small window, Socko watched my assistant hide an apple in a large tractor tire in the outdoor enclosure, while the rest of the colony was kept behind closed doors. Then we released the colony, holding Socko back until last. The first thing he did after coming out the door was to climb onto the tire and peek into it, checking on the apple. He left it alone, though, and nonchalantly walked away from the scene. He waited for more than twenty minutes, until everyone was otherwise occupied, and then went to collect the fruit. This was clever, since he might otherwise have lost his prize.
The truly interesting twist came years later, however, when we repeated this experiment. Socko had been tested only once, and we showed the video to a visiting camera crew. But as is typical, the crew trusted its own filming better and insisted on redoing the whole test. By this time Socko was the alpha male and hence could not be used anymore. Being of high rank, he would have had no reason to conceal what he knew about hidden food. So instead we selected a low-ranking female named Natasha and did everything nearly same. We locked up all the chimps and let Natasha watch through the window while we hid an apple. This time we dug a hole in the ground, put the apple into it, and covered it with sand and leaves. We did this so well that afterward we barely knew where we’d put the fruit.
After the others were released, Natasha finally entered the enclosure. We waited anxiously, following her with several cameras. She showed a pattern similar to Socko’s and moreover displayed a far better sense of location than we did. She passed slowly over to the precise hiding spot, then returned ten minutes later to confidently dig up the fruit. While she did so, Socko stared at her with apparent surprise. It is not every day that someone pulls an apple out of the ground! I worried that Socko might punish her for snacking right in front of him, but no, Socko ran straight to the tractor tire! He looked into it from several angles, but obviously it was empty. It was as if he had concluded that we were hiding fruit again—and he recalled the exact location we’d used before. This was most remarkable since I am pretty sure Socko had had only one experience of this kind in his whole life, which had occurred five years earlier.