The Editors of TIME - TIME the Science of Memory

THE SCIENCE OF MEMORY

The Story of Our Lives

INTRODUCTION

WHY WE REMEMBER

From an evolutionary point of view, it comes down to survival of the fittest. He who endures remembers where the food is and where the predators lurk

By Eileen Daspin

Early humans had to remember where predators hid. Illustration from LHomme Primitif by Louis Figuier.

FOR AN EXPERIMENT ON NAVIGATIONAL skills and natural selection, the settinga Santa Barbara, Calif., farmers market on a Saturday morningcould not have been more Darwinian. So was the question at hand: How would spatial memory and adaptive behavior play out for a modern hunter-gatherer?

To find out, a group of psychology professors posted themselves at the markets entrance and enlisted shoppers as foragers. Eighty-six subjects were led along intentionally circuitous routes to pre-selected food stalls. There, they tasted the farmers goods, were guided to the center of the market and finally were given a special device to indicate the locations of the foods they had sampled. True to Paleolithic form, the shoppers easily identified the locations that provided goods with the most energyolive oil, avocados and nutsbut struggled to place booths stocking calorie-light leafy greens.

I was surprised at how cleanly the results came out, says psychology professor Joshua New, one of the designers of the study, who now teaches at Columbia University. People hadnt thought about encoding landmarks like that. But if you eat at a subpar restaurant, youre not going to commit memory to learning how to get back there.

From an evolutionary point of view, the reason we remember, like pretty much all human activity, comes down to survival of the fittest. He who is going to make it out alive remembers where the food is. And what the bad guys look like. And the best place to hide from predators. What scientists call adaptive memorywhich is always functioning to figure out new solutions to problemsis key to nearly everything we do. We have to remember to physically navigate the world, to reproduce, to interact with others, to recognize kin, to know the truth of a situation. Memory is what allows us to learn, to acquire, to store and retrieve information.

As machines, our memories are amazing, able to store long-term some 2.5 petabytes of data, by one professors calculation. Thats the equivalent of 300 million hours of television programming. The catch is that memories are as faulty as they are essential. No two people remember the same event the same way, a fact famously illustrated in the Japanese crime drama Rashomon , in which four people each remembered killing the same samuraiincluding the samurai himself, who returned from the dead to testify that he had committed hara-kiri.

Our memories are amazing, able to store long-term some 2.5 petabytes of dataabout 300 million hours of television programming.

Memory is so crucial, we even forget to remember, with the brain pushing out less-important memories to make room for the more-important ones. This is a phenomenon that Friedrich Nietzsche called active forgetfulness, by his lights, an important component of happiness. The German philosophers argument wasnt that you should be pleased you forgot where you parked your car, but rather that not remembering paves the way for peace of mind. To shut the doors and windows of consciousness for a while... Nietzsche wrote in On the Genealogy of Morals/Ecce Homo , allows for a little tabula rasa of consciousness to make room for something new... like a doorkeeper or guardian of mental order, rest and etiquette.

Research suggests that memory literally starts in utero. When Dutch professors put a honking, vibrating device on the abdomens of women in their 30th to 38th weeks of pregnancy, they found that the fetuses quickly recalled the noise, so that when the device was sounded 10 minutes later, they didnt squirm and their heartbeats remained stable. The 34-week-olds even remembered the noise four weeks later. Its like getting used to a New York train station, lead author J.G. Nijhuis told Scientific American . It is a learning capability to distinguish safe from unsafe stimuli. It is a primitive form of memory.

Then it gets a little more complicated. Infants and toddlers remember, but by about age 7, the first three years of memories are almost entirely erased from the conscious memory and overlaid with new ones. From there, our memories shift and evolve, colored constantly by our experiences. Why do we remember? As Oscar Wilde once suggested, to fill in the diary we all carry about with us.

Editor Edward Felsenthal

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THE SCIENCE OF MEMORY

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Editor Eileen Daspin

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