Most People Consistently Visit 25 Different Places in Their Daily Lives

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iStock

We move around a lot less during our daily lives than you might expect. Based on data from 40,000 people, a new study on human mobility finds that we tend to frequent only 25 places at any given time in our lives.

In the study, published in Nature Human Behaviour, researchers from City, University of London, the Technical University of Denmark, and Sony Mobile Communications found that people tend to have a maximum number of 25 places that they visit regularly, and if they begin frequenting a new place, they probably stop going to another, keeping their total number of haunts constant.

The researchers used several different datasets to understand how people move through their lives, including studies with college students and university employees, data from a smartphone activity tracker called Lifelog, and a Nokia research project that tracked the behavior of a group of cell phone users living near Lake Geneva in Switzerland between 2009 and 2011.

They found that people constantly face trade-offs between the curiosity that drives us to check out new places and the laziness and comfort that keeps us going back to our regular haunts. As a result, the number of locations we tend to visit stays relatively steady. People “continually explore new places yet they are loyal to a limited number of familiar ones,” the authors write.

Though that number may sound a little low to anyone with wanderlust, it makes sense. People don’t have infinite time or resources. Even the number of friends we’re capable of keeping up with is rather limited—anthropologist Robin Dunbar famously hypothesizes that humans can only sustain around 150 friendships at a time, and only five of those friends will be truly close ones. And if that’s our upper limit for connections we can technically maintain without ever leaving our computers, it makes sense that we would be able to sustain even fewer connections to places, which by nature require some amount of travel. If you find a new restaurant and become a regular, it’s probably at the expense of another restaurant you used to visit all the time.

However, the study found that the number of places you frequent can’t necessarily be explained only by the amount of free time you have. The researchers argue that “the fixed capacity is an inherent property of human behavior.” The 25-place rule held even if they adjusted for the time people spent at each location. They also found that the more social a person was, the more places they visited.

The researchers hope to continue their work by looking at connections between mobility and Dunbar’s work on social ties, figuring out how exactly your social life plays into how you move around the world.

A Simple Skin Swab Could Soon Identify People at Risk for Parkinson's

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iStock.com/stevanovicigor

More than 200 years have passed since physician James Parkinson first identified the degenerative neurological disorder that bears his name. Over five million people worldwide suffer from Parkinson’s disease, a neurological condition characterized by muscle tremors and other symptoms. Diagnosis is based on those symptoms rather than blood tests, brain imaging, or any other laboratory evidence.

Now, science may be close to a simple and non-invasive method for diagnosing the disease based on a waxy substance called sebum, which people secrete through their skin. And it’s thanks to a woman with the unique ability to sniff out differences in the sebum of those with Parkinson's—years before a diagnosis can be made.

The Guardian describes how researchers at the University of Manchester partnered with a nurse named Joy Milne, a "super smeller" who can detect a unique odor emanating from Parkinson's patients that is unnoticeable to most people. Working with Tilo Kunath, a neurobiologist at Edinburgh University, Milne and the researchers pinpointed the strongest odor coming from the patients' upper backs, where sebum-emitting pores are concentrated.

For a new study in the journal ACS Central Science, the researchers analyzed skin swabs from 64 Parkinson's and non-Parkinson's subjects and found that three substances—eicosane, hippuric acid, and octadecanal—were present in higher concentrations in the Parkinson’s patients. One substance, perillic aldehyde, was lower. Milne confirmed that these swabs bore the distinct, musky odor associated with Parkinson’s patients.

Researchers also found no difference between patients who took drugs to control symptoms and those who did not, meaning that drug metabolites had no influence on the odor or compounds.

The next step will be to swab a a much larger cohort of Parkinson’s patients and healthy volunteers to see if the results are consistent and reliable. If these compounds are able to accurately identify Parkinson’s, researchers are optimistic that it could lead to earlier diagnosis and more effective interventions.

[h/t The Guardian]

World’s Oldest Stored Sperm Has Produced Some Healthy Baby Sheep

A stock photo of a lamb
A stock photo of a lamb
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It’s not every day that you stumble across a 50-year-old batch of frozen sheep sperm. So when Australian researchers rediscovered a wriggly little time capsule that had been left behind by an earlier researcher, they did the obvious: they tried to create some lambs. As Smithsonian reports, they pulled it off, too.

The semen, which came from several prize rams, had been frozen in 1968 by Dr. Steve Salamon, a sheep researcher from the University of Sydney. After bringing the sample out of storage, researchers thawed it out and conducted a few lab tests. They determined that its viability and DNA integrity were still intact, so they decided to put it to the ultimate test: Would it get a sheep pregnant? The sperm was artificially inseminated into 56 Merino ewes, and lo and behold, 34 of them became pregnant and gave birth to healthy lambs.

Of course, this experiment wasn’t just for fun. They wanted to test whether decades-old sperm—frozen in liquid nitrogen at -320°F—would still be viable for breeding purposes. Remarkably, the older sperm had a slightly higher pregnancy rate (61 percent) than sheep sperm that had been frozen for 12 months and used to impregnate ewes in a different experiment (in that case, the success rate was 59 percent).

“We believe this is the oldest viable stored semen of any species in the world and definitely the oldest sperm used to produce offspring,” researcher Dr. Jessica Rickard said in a statement.

Researchers say this experiment also lets them assess the genetic progress of selective breeding over the last five decades. “In that time, we’ve been trying to make better, more productive sheep [for the wool industry],” associate professor Simon de Graaf said. “This gives us a resource to benchmark and compare.”

[h/t Smithsonian]

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