Many of us spend part of each day surrounded by strangers, whether on our daily commute (上下班往返), or sitting in park or cafe. But most of them remain just that-strangers. However, new evidence has shown that plucking up (鼓起) the courage to strike up conversation might be good for our health.

Nicholas Epley from the University of Chicago and Juliana Schroeder from the University of California are behavioural scientists. They wanted to know whether solitude is a more positive experience than interacting with strangers, or if people misunderstand the consequences of distant social connections. They found that many people feel uncomfortable and frightened talking to others and their research suggested that when we make an initial conversation “we consistently underestimate (低估) how much a new person likes us.” It seems we think that all the things could go wrong and why someone wouldn’t want to talk with us.

Their research involved an experiment with a group of Chicago commuters and found that “every participant in our experiment who actually tried to talk to a stranger found the person sitting next to them was happy to chat.” From this and other research, the conclusion is that connecting with strangers is surprisingly pleasant and it has a positive impact on our wellbeing. It’s true that talking can make you feel happier and happiness can lead to better mental health.

However, if you’re’ an introvert (性格内向者), the thought of speaking to someone new might make you anxious. But the American research found “both extroverts (性格外向者) and introverts are happier when they are asked to behave in an extroverted manner.” So maybe, if you’re a loner, it’s time to come out of your shell and make some small talk with a stranger-it could be the beginning of a new friendship.

Challenging work that requires lots of analytical thinking, planning and other managerial skills might help your brain stay sharp as you age, a study published Wednesday in the journal Neurology suggests.

Researchers from the University of Leipzig in Germany gathered more than 1, 000 retired workers who were over age 75 and assessed the volunteers’ memory and thinking skills through a battery of tests. Then, for eight years, the scientists asked the same group to come back to the lab every 18 months to take the same sorts of tests.

Those who had held mentally stimulating(刺激), demanding jobs before retirement tended to do the best on the tests. And they tended to lose cognitive(认知) function at a much slower rate than those with the least mentally challenging jobs. The results held true even after the scientists accounted for the participants’ overall health status.

“This works just like physical exercise, ” says Francisca Then, who led the study. “After a long run, you may feel like you’re in pain, you may feel tired. But it makes you fit. After a long day at work-sure, you will feel tired, but it can help your brain stay healthy. ”

It's not just corporate jobs, or even paid work that can help keep your brain fit, Then points out. A waiter’s job, for example, that requires multitasking, teamwork and decision-making could be just as stimulating as any high-level office work. And “running a family household requires high-level planning and coordinating(协调), ” she says. “You have to organize the activities of the children and take care of the bills and groceries. ”

Of course, our brains can decline as we grow older for lots of reasons-including other environmental influences or genetic factors. Still, continuing to challenge yourself mentally and keeping your mind busy can only help.

We’ve all felt the tap to the soul you get from driving by your old high school or hearing a tune you once danced to. But why is that feeling so universal?

Nostalgia, a combination of the Greek words nostos (homecoming) and algos (pain), was a special type of homesickness associated with soldiers fighting far-off wars. Seventeenth century physicians worried such thoughts put health at risk. In the 19th century, doctors believed it could cause irregular heartbeat, fever, and death.

Our understanding of nostalgia has developed since then. “It’s a very mixed emotion,” says Frederick Barrett, a neuroscientist. That makes it hard to fit into existing theory, which typically categorizes emotions as either positive or negative. And triggers — the cars, music or smells — are extremely personal. Therefore, designing a standardized study is difficult.

But we do know nostalgia has a marked effect on us: brain imaging studies show that those experiences have their own neural signature. Neuroscientists argued that the emotion is co-produced by the brain’s recall and reward systems. They found that nostalgic images use the memory-managing hippocampus (海马区) more than other sights, as people mine autobiographical (个人经历的) details deep in the past. This mental effort pays off:as the hippocampus activates, so does one of the brain’s reward centers.

That longing for the past might be a protective mechanism, says Tim Wildschut, a professor. His work also suggests a more primitive purpose for the feeling: it developed to remind our ancient ancestors of pleasant physical feelings during periods of discomfort and pain.

Recent research suggests the occasional look backwards can give us a boost in unnoticeable ways: by increasing self-respect and protecting against depression. Nostalgia’s apparent power to jump-start one’s memory also seems to improve recall ability in people with Alzheimer’s disease.

New flavors of “reminiscence therapy” (回忆疗法) are emerging around the world. In 2018, the George G. Glenner Alzheimer’s Family Centers opened its first Town Square, an adult daycare facility designed to look like a small town in 1950s America. Though Town Square has yet to publish peer-reviewed data on the success of the program, clients say it has helped seniors access dusty memories and reconnect with loved ones.

Scientists need a lot more information to adequately characterize this complex and bittersweet feeling. But while centuries of doctors considered nostalgia a deadly disease, we now know: it can help us make it through today.