Free The Happiness of Pursuit: What Neuroscience Can Teach Us About the Good Life by Shimon Edelman Page B

possibility space. In such a space, one can still meaningfully discuss proximity (which translates into similarity between abstract objects, such as two action plans). Even for us, however, the roots of abstract representations are firmly planted in the basic functional need to explore and make sense of the wild environment into which we are born, armed only with the knowledge of how to learn and a notion that every thing has its place.
    For human babies, forays into the wild begin in the playroom or in the backyard as they crawl about and explore the little world centered on the place where they are released by a caregiver. Among the kinds of regularities that babies need to discern in the maelstrom of sensory information that spins around them are names for things—certain sound or gesture combinations that go with certain objects or actions. Sometimes objects do receive explicit labels; only inconsiderate or stoned parents would ever exclaim, “Look at the bunny!” while pointing at something other than an actual bunny (live or stuffed). More often than not, however, the baby has only circumstantial evidence to go by, as when an object gets both mentioned and shown, but not at the same time.
    Experimental studies show that in such cases babies learn more reliably if the naming of an object and its appearance are made to share the same physical location—for instance, by offering the baby a verbal label for a novel object while snapping fingers in the place where it had appeared earlier. In using space in this manner, human babies very likely rely on the same brain circuits and mechanisms that support location-bound episodic memory in other mammals (all of which have a hippocampus). It is because of this sharing of dedicated computational resources between episodic memory and language-related tasks that drivers are more likely to get lost if they are made to navigate a not entirely familiar city while maintaining a conversation. 13

A Moveable Feast
     
    Not only mammals qualify for an episodic memory system: chickadees, nutcrackers, jays, and titmice have it too. These and many other species of birds depend for their survival on caching food items, such as seeds or dead worms, that they later retrieve. The number of caches typically runs in the thousands, underscoring the large memory capacity that is needed to support this behavior. Carefully controlled studies have revealed that this memory is episodic: rather than relying exclusively on common characteristics of a cache location, birds memorize the actual locations they visit. They also remember the type of the food item that they store in each location: scrub jays, for instance, return to caches of perishable wax worms before revisiting places where they have stored pine nuts, which do not spoil. 14
    Because of the usual selection pressure, the ability to memorize past episodes is indulged by evolution only insofar as it carries future dividends. The scrub jay’s obvious future payoff from remembering where it cached a wax worm is a tasty snack at a later time, but there is also a less obvious and much more interesting side to episodic memory, avian or human: it can support time-travel, of a kind that is perfectly compatible with the laws of physics and fully paid for by the evolutionary benefits it confers.
    It is easy to see how a mind that is equipped with episodic memory has what it takes to travel mentally into the past: it can do so by recalling the circumstances of previously experienced episodes and re-creating them in the represented present, within the workspace of the mind’s war room. With only a slight modification, the very same set of cognitive tools can also support mental travel into the future: one needs merely to modify certain aspects of the represented situation to turn retrospection into prospection. 15
    The study that demonstrated this ability in scrub jays took advantage of their gourmand predisposition. Jays prefer not to eat the same food