In the new report, researchers Paul Frankland and Blake Richards of the University of Toronto propose that the goal of memory is not to transmit the most accurate information over time. Rather, they say, it's to optimize intelligent decision-making by holding onto what's important and letting go of what's not.
The researchers came to this conclusion after looking at years of data on memory, memory loss, and brain activity in both humans and animals. One of Frankland's own studies in mice, for example, found that as new brain cells are formed in the hippocampus -- a region of the brain associated with learning new things -- those new connections overwrite old memories and make them harder to access.
This constant swapping of old memories for new ones can have real evolutionary benefits, they say. For example, it can allow us to adapt to new situations by letting go of outdated and potentially misleading information. "If you're trying to navigate the world and your brain is constantly bringing up conflicting memories, that makes it harder for you to make an informed decision," says Richards.
Our brains also help us forget specifics about past events while still remembering the big picture, which the researchers think gives us the ability to generalize previous experiences and better apply them to current situations.
"We all admire the person who can smash Trivial Pursuit or win at Jeopardy, but the fact is that evolution shaped our memory not to win a trivia game, but to make intelligent decisions," says Richards. "And when you look at what's needed to make intelligent decisions, we would argue that it's healthy to forget some things."
So what does that mean for those of us who frequently forget things we just read, people we just met, and where we put our keys? For one, we should stop being so hard on ourselves, says Richards -- to a certain extent.
"You don't want to forget everything, and if you're forgetting a lot more than normal that might be cause for concern," he says. "But if you're someone who forgets the occasional detail, that's probably a sign that your memory system is perfectly healthy and doing exactly what it should be doing."
Especially in today's computers-at-our-fingertips society, Richards says, our brains no longer need to store information like phone numbers and facts easily found on Google. "Instead of storing this irrelevant information that our phones can store for us, our brains are freed up to store the memories that actually do matter for us," he says.
Richards also recommends "cleaning out" your memory system on a regular basis by doing regular gym workouts. "We know that exercise increases the number of neurons in the hippocampus," he says. Yes, that may cause some memories to be lost, he says -- "but they're exactly those details from your life that don't actually matter, and that may be keeping you from making good decisions."