Barely Any Land on Earth Is Untouched by Humans


A new study, published in the journal Proceedings of the National Academy of Sciences (PNAS), suggests that nearly all of the world’s unspoiled nature is entirely gone. In fact, most of it disappeared at least several thousand years ago, thanks to human activity, The Washington Post reports.

Nicole Boivin from the University of Oxford and the Max Planck Institute for the Science of Human History teamed up with scientists from the UK, U.S., and Australia to pore over archaeological, fossil, and ancient DNA data. The researchers concluded that humans began affecting the world’s natural ecosystems long before cars, housing developments, or factories existed. “Pristine’ landscapes simply do not exist and, in most cases, have not existed for millennia,” they said in a release.

The paper outlines the major phases when humans shaped the world and altered our world’s ecosystems: global human expansion during the Late Pleistocene; the Neolithic spread of agriculture; the era of humans colonizing islands; and the emergence of urban trading societies.

Here’s a rough timeline: modern humans arose in Africa roughly 190,000 years ago, and by 50,000–70,000 years ago (some say even earlier) had begun venturing out of the home continent. Human hunting is presumed to have helped drive the extinctions of some types of large or giant animals, called megafauna, in Australia, Tasmania, and later the Americas between 50,000 and 10,000 years ago. One example of our early impact occurred some 20,000 to 23,000 years ago, when humans introduced a new species—a marsupial that lived in New Guinea, now called the northern common cuscus—to Indonesia and other regions in the South Pacific.

Astoundingly enough, all this activity preceded the advent of agricultural societies during the Holocene period, which began about 11,700 years ago. (We still live in the Holocene.) By this time, the human species was widely dispersed throughout the world. Farmers began favoring certain animal, tree, and plant species, which thrive today thanks to our ancestors’ green thumbs. They used fire to burn land for agriculture, and to draw animals out into the open for easier hunting. Humans’ agricultural practices also affected everything from forests (after all, we had to clear land for planting food) to the atmosphere’s greenhouse gas composition. Sometime during this era, livestock and poultry were domesticated and spread from the Near East to across the globe.

Meanwhile, seafaring societies began spreading pests from one island to another, since various species of rats, mice, insects, and lizards stowed away onboard sailors’ boats. As humans colonized these new lands, they also threatened indigenous animals, contributed to deforestation, introduced new crops, generally altered these virgin landscapes for good.

As humanity’s become more advanced, our impact on our environment has grown. During the Industrial Revolution, factory emissions dramatically altered atmospheric carbon dioxide concentrations. In fact, researchers have even argued that these gases mark the end of the Holocene and the beginning of a new geological epoch called the Anthropocene.

In short, humans have a long, long history of affecting and changing the natural world. However, the study’s researchers don’t necessarily think that’s a bad thing. We’ll never be able to undo the damage, but we can mindfully monitor and shape the way we physically impact the world.

“The fact that we’ve been changing the planet for so long, with both positive and negative consequences, suggests that we can try to take control of the transformation, and make it less detrimental,” Boivin told The New Yorker

[h/t The Washington Post]

This Just In
Yes, Parents Do Play Favorites—And Often Love Their Youngest Kid Best

If you have brothers or sisters, there was probably a point in your youth when you spent significant time bickering over—or at least privately obsessing over—whom Mom and Dad loved best. Was it the oldest sibling? The baby of the family? The seemingly forgotten middle kid?

As much as we'd like to believe that parents love all of their children equally, some parents do, apparently, love their youngest best, according to The Independent. A recent survey from the parenting website Mumsnet and its sister site, the grandparent-focused Gransnet, found that favoritism affects both parents and grandparents.

Out of 1185 parents and 1111 grandparents, 23 percent of parents and 42 percent of grandparents admitted to have a favorite out of their children or grandchildren. For parents, that tended to be the youngest—56 percent of those parents with a favorite said they preferred the baby of the family. Almost 40 percent of the grandparents with a favorite, meanwhile, preferred the oldest. Despite these numbers, half of the respondents thought having a favorite among their children and grandchildren is "awful," and the majority think it's damaging for that child's siblings.

Now, this isn't to say that youngest children experience blatant favoritism across all families. This wasn't a scientific study, and with only a few thousand users, the number of people with favorites is actually not as high as it might seem—23 percent is only around 272 parents, for instance. But other studies with a bit more scientific rigor have indicated that parents do usually have favorites among their children. In one study, 70 percent of fathers and 74 percent of mothers admitted to showing favoritism in their parenting. "Parents need to know that favoritism is normal," psychologist Ellen Weber Libby, who specializes in family dynamics, told The Wall Street Journal in 2017.

But youngest kids don't always feel the most loved. A 2005 study found that oldest children tended to feel like the preferred ones, and youngest children felt like their parents were biased toward their older siblings. Another study released in 2017 found that when youngest kids did feel like there was preferential treatment in their family, their relationships with their parents were more greatly affected than their older siblings, either for better (if they sensed they were the favorite) or for worse (if they sensed their siblings were). Feeling like the favorite or the lesser sibling didn't tend to affect older siblings' relationships with their parents.

However, the author of that study, Brigham Young University professor Alex Jensen, noted in a press release at the time that whether or not favoritism affects children tends to depend on how that favoritism is shown. "When parents are more loving and they're more supportive and consistent with all of the kids, the favoritism tends to not matter as much," he said, advising that “you need to treat them fairly, but not equally.” Sadly for those who don't feel like the golden child, a different study in 2016 suggests that there's not much you can do about it—mothers, at least, rarely change which child they favor most, even over the course of a lifetime.

[h/t The Independent]

15 Scientific Reasons Spring Is the Most Delightful Season

Summer, winter, and fall may have their fans, but spring is clearly the most lovable of the four seasons. Not convinced? Here are 15 scientific reasons why spring is great:


road and field on a sunny day

Spring marks the end of blistering winter and the transitional period to scorching summer. In many places, the season brings mild temperatures in the 60s and 70s. People tend to be most comfortable at temperatures of about 72°F, research shows, so the arrival of spring means you can finally ditch the heavy winter layers and still be comfortable.


sunny sky

Following the spring equinox, days begin lasting longer and nights get shorter. Daylight Saving Time, which moves the clock forward starting in March, gives you even more light hours to get things done. Those extra hours of sun can be a major mood-booster, according to some research. A 2016 study of students in counseling at Brigham Young University found that the longer the sun was up during the day, the less mental distress people experienced.


blue bird on branch

Many animals migrate south during the winter, then head north as temperatures rise. For relatively northern regions, there is no better indicator of spring than birds chirping outside your window. Their northward migration can start as early as mid-February and last into June, meaning that throughout the spring, you can expect to see a major avian influx. In addition to the satisfaction of marking species off your bird-watching checklist, seeing more of our feathered friends can make you happy. In 2017, a UK study found that the more birds people could see in their neighborhoods, the better their mental health.


Baby squirrels

Many animals reproduce in the spring, when temperatures are warmer and food is plentiful. Baby bunnies, ducklings, chipmunks, and other adorable animals abound come spring. Studies have found that seeing cute animals can have positive effects on humans. For instance, one small study in 2012 found that when college students looked at cute images of baby animals, they were better at focusing on a task in the lab. Being able to watch fluffy baby squirrels frolic outside your office window might make spring your most productive season of the year.


flowers hanging outside of a house

In 2015, a pair of public policy researchers discovered a hidden upside to "springing forward" for Daylight Saving Time. It reduced crime. When the sun set later in the evening, the study published in the Review of Economics and Statistics found, robbery rates fell. After Daylight Saving Time started in the spring, there was a 27 percent drop in robberies during that extra hour of evening sunlight, and a 7 percent drop over the course of the whole day.


child with rainbow umbrella jumping in puddle

Warmer temperatures mean you can spend more time outside without freezing your feet off, which is great for mental health. Across the seasons, research has found that taking walks in nature slows your heart rate and makes you more relaxed, but some research indicates that there is something special about spring's effect on your brain. A 2005 study from the University of Michigan linked spending 30 minutes or more outside in warm, sunny spring weather to higher mood and better memory. But the effect reverses when spring ends, since being outside in the warmest days of summer is usually pretty uncomfortable.


woman writing in a park

That same University of Michigan study found that spending time outside in the sunny spring weather isn't just a mood booster, it actually can change the way people think. The researchers found that being outdoors broadened participants' minds, leaving them more open to new information and creative thoughts.


leaves budding in spring

Spring brings green growth back to plants and trees. Depending on where you live, trees may begin sporting new leaves as early as mid-March. That successful spring leaf growth ensures a cool canopy to relax under during the hot summer—a hugely important factor in keeping cities comfortable. According to researchers, vegetation plays a big role in mitigating the urban heat island effect. When trees release water back into the air through evapotranspiration, it can cool down the areas around them by up to 9°F, according to the EPA.


tulip bulbs

It's amazing what a little sun can do for plants and grass. Through photosynthesis, plants convert sunlight, carbon dioxide, and water into food, releasing oxygen in the process. That means as plants start to grow in the spring, they pull carbon out of the atmosphere, providing an important environmental service. Plants take in roughly 25 percent of the carbon emissions humans produce, absorbing more than 100 gigatons of carbon through photosynthesis each growing season. Because of this, the amount of carbon dioxide in the atmosphere drops each spring and summer. (Unfortunately, it rises in the winter, when most plants aren't growing.)


wooden box full of fresh produce

Many vegetables and some fruits are harvested in the spring. 'Tis the season to get your local asparagus, greens, peas, rhubarb, and other fresh produce. Getting more fruits and vegetables into your diet isn't just good for the body; it's good for the soul. A 2016 study of more than 12,000 Australians found that when people increased the amount of fruits and vegetables in their diet, they felt happier and had higher rates of life satisfaction. If they increased their intake by eight portions a day (a tall order, we know) the psychological gains were equivalent to the change in well-being people experience when they go from being unemployed to having a job, the researchers found.


Flowers in a vase

After months spent conserving energy, flowers bloom in the spring, once they sense that the days have grown longer and the weather has turned warmer. That's good for humans, because several studies have shown that looking at flowers can make you happy. A 2008 study of hospital patients found that having flowers in the room made people feel more positive and reduced their pain and anxiety [PDF]. Another study from Rutgers University found that when participants were presented with a bouquet of flowers, it resulted in what scientists call a "true smile" a full 100 percent of the time. Seeing flowers had both "immediate and long-term effects" that resulted in elevated moods for days afterward, according to the researchers [PDF].


woman tying shoes in flower field

While it's important to keep moving no matter what the weather, research shows that working out can be more beneficial if you do it outside. A 2011 study found that, compared with an indoor workout, exercising outdoors in nature increased energy levels, made people feel revitalized, and decreased tension, among other positive effects. People who worked out in the fresh air also tended to say they enjoyed the experience more and would be likely to repeat it, suggesting that using nature as your gym might help you stick with your exercise regimen. While those benefits probably extend to winter, too, it's a whole lot easier to stomach the idea of a run once the weather warms up.


dew on grass and a daisy

Flu season in the U.S. typically lasts through the fall and winter, usually peaking between December and February and tapering off during the spring. The seasonal change is in part because of dry air. Cold temperatures mean a drop in humidity, and indoor heating only makes the air drier. This lack of moisture in the air can dry out your skin and the nasal cavities, leading to nose bleeds, irritated sinuses, and a greater risk of getting sick. Since the mucus in your nose is designed to trap viruses, when it dries up, you're more likely to catch something nasty, like the flu. As the weather warms up and becomes more humid throughout the spring, that mucus comes back. As the season wears on, not only can you lay off the body lotion, but you can probably put away the tissues—if you don't have spring allergies, that is.


windows open on a red house

Temperate weather makes it easier to get the fresh air you need. Opening your windows and allowing the breeze in serves as an important way to ventilate indoor spaces, according to the EPA. A lack of ventilation can lead to an unhealthy concentration of indoor pollutants from sources like cleaning product fumes, certain furniture and building materials, and stoves (especially gas ones), posing a threat to your health and comfort. Winter brings the highest rates of indoor pollutants like nitrogen oxide, a 2016 study of unventilated stove use in homes found. Spring brings the perfect opportunity to throw open those windows and doors and get the air moving again.


woman enjoying sitting in the sun

Sunlight triggers your body to produce the vitamin D, which keeps your bones strong. At northern latitudes, it's extremely difficult to get enough sun exposure naturally to maintain healthy vitamin D levels during the winter—even if you did want to expose your skin to the elements—but that starts to change during the spring. One Spanish study found that in Valencia (which shares a latitude with Philadelphia, Denver, Baltimore, Kansas City, and several other major U.S. cities), people only need 10 minutes outside with a quarter of their bodies exposed to the spring sunshine to get an adequate daily dose of vitamin D.

A version of this story originally ran in 2014.


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