Scientists think humans developed right-handedness thanks to these 2 factors |
Since the dawn of man, right-handedness has reigned supreme without much intel as to why. While our ape brethren also develop strong preferences toward one hand over another, there is generally an equal number of left- and right-handed individuals. Conversely, 90% of humans are right-handed. And now, scientists think they have discovered when this prevalence developed.
A new study led by researchers at the University of Oxford suggests that it went hand-in-hand (pardon the pun) with two other major evolutionary shifts: walking on two legs and developing much larger brains.
Thousands of primates helped narrow the possibilities
The research, published in PLOS Biology, analyzed data from 2,025 monkeys and apes representing 41 different primate species. All the evolutionary factors tested—tool use, diet, habitat, body size, social structure, brain size, movement patterns, etc.—seemed to match human data, leaving no real clues as to why our species decided to become almost exclusively right-handed.
However, that changed once researchers added brain size and the ratio between arm length and leg length to their analysis. Suddenly humans, with their larger brains and legs much longer than their arms (a hallmark trait of bipedal walking), stood out from an evolutionary standpoint.
These factors, along with other fossil records, help us imagine a timeline that looked something like this:
Human ancestors (Ardipithecus and Australopithecus, respectively) began walking upright, allowing one hand to become specialized over the other. At this point, there would likely be an equal number of left-handers to right-handers.
As our brains grow to incorporate more complex activities like using tools, communicating through a wide array of gestures, and participating in complex tasks like cooking and performing rituals, so too does our right-hand bias. In fact, the same 90% right-hand dominance is already present around 2.6 million years ago…before Homo sapiens and Neanderthals entered the scene.
One side of the brain might hold an important clue
That third factor (complex tasks) is particularly interesting. Sequentially organized behaviors, also known as hierarchical action, are often believed to be something managed by the brain’s left hemisphere. The left hemisphere also controls all the motor functions and movements on the right side of the body. That said, all three elements, along with the fact that humans learn by imitating their parents, likely played equally important roles in the evolutionary narrative.
Ancient “hobbits” added another intriguing clue
Backing this theory is the “hobbit” species discovered in Indonesia. This ancient humanoid species maintained smaller brains and the ability to climb while also walking. Conversely, it did not have nearly the same amount of right-hand dominance.
There are, of course, more mysteries to unravel. Why some of us are still left-handed, for instance. Or whether the limb preference of other animals suggests a similar evolutionary pattern. But, regardless, the study reminds us that even the most seemingly simple quirks that make us human actually tell an incomprehensibly vast story of how we came to be in the first place.
While a bottle of bubbles might seem out of place in a hospital setting, you might be surprised to learn that, for thousands of children around the world born with cleft lip and palate, they can be a helpful tool in comprehensive cleft care. Lilia, who was born with cleft lip and palate in 2020, is one of the many patients who received this care.
As a toddler, Lilia underwent two surgeries to treat cleft lip and palate with Operation Smile’s surgical program in Puebla, Mexico. Because of Operation Smile’s comprehensive care, it wasn’t long before her personality transformed: Lilia went from a quiet and withdrawn toddler to an exuberant, curious explorer, babbling, expressing herself with a variety of sounds, and engaging with others like any child her age.
Lilia is now a healthy five-year-old, with the same cheerful attitude and boundless energy. Her progress is the result of care at every level, from surgery to speech therapy to ongoing support at home—but it’s also evidence that small, sustained interventions throughout it all can make a meaningful difference.
Cleft Conditions: A Global Problem
Since 1982, Operation Smile has provided cleft lip and cleft palate surgeries to more than 500,000 patients worldwide with the help of generous volunteers and donors. Cleft conditions are congenital conditions, meaning they are present at birth. With cleft lip and palate, the lip or the roof of the mouth do not form fully during fetal development. Cleft conditions put children at risk for malnutrition and poor weight gain, since their facial structure can make feeding challenging. But cleft conditions can have an enormous social impact as well: Common difficulties with speech can leave kids socially isolated and unable to meet the same developmental milestones as their peers.
Surgery is a vital step in treating cleft conditions, but it’s also just one part of a much larger solution. Organizations like Operation Smile emphasize the importance of multi-disciplinary teams that provide comprehensive, long-term care to patients across many years. This approach, which includes oral care, speech therapy, nutritional support, and psychosocial care, not only aids in physical recovery from surgery but also helps children develop the skills and confidence to eat easily, speak clearly, and engage in everyday life. This ensures that each patient receives the full range of support they need to thrive.
A Playful (and Powerful) Solution
Throughout a patient’s care, simple tools like bubbles can play a meaningful role from start to finish.
Immediately before surgery, children are often in a new and unfamiliar environment far from home, some of them experiencing a hospital setting for the first time. When care providers or loved ones blow bubbles, it’s a simple yet effective technique: Not only are the children soothed and distracted, the bubbles also help create a sense of joy and playfulness that eases their anxiety.
In speech therapy, bubbles can take on an even more important role. Blowing bubbles requires controlled airflow, as well as the ability to form a rounded “O” shape with the lips, which are skills that children with cleft conditions may struggle to develop. Practicing these skills with bubbles allows children to gently strengthen their facial muscles, improve breath control, and support the motor skills needed for speech development. Beyond that, blowing bubbles can help kids connect with their parents or providers in a way that’s playful, comforting, and accessible even for very young patients.
Finally, bubbles often follow patients with cleft conditions home in the “smile bags” that each patient receives when the surgical procedure is finished. Smile bags, which help continue speech therapy outside of the hospital setting, can contain language enrichment booklets, a mirror, oxygen tubing, and bubbles. While regular practice with motor skills can help with physical recovery, small acts of play help as well, giving kids space to simply enjoy themselves and join in on what peers are able to do.
Bubbles at Home and Beyond
Today, because of Operation Smile’s dedication to comprehensive cleft care, Lilia is now able to make friends and speak clearly, all things that could have been difficult or impossible before. Instead of a childhood defined by limitation, Lilia—and others around the world—can look forward to a childhood filled with joy, learning, discovery, friends, and new possibilities.
CTA: Lilia’s life was changed for the better with the care she received through Operation Smile. Find out how you can make an impact in other children’s lives by visiting operationsmile.org today.
Many of us have walked into an old building and felt some kind of eeriness. Depending on your own personal beliefs, you might be inclined to attribute this feeling to the presence of something supernatural. But science has found another culprit that haunts our psyche in these places, and it’s not ghosts.
Researchers at MacEwan University in Edmonton, Canada, found that when people were exposed to infrasound, which is typically imperceptible to humans, they still experienced a rise in cortisol levels and irritation.
“In an old building, there is a good chance that infrasound is present, particularly in basements where aging pipes and ventilation systems produce low-frequency vibrations,” noted senior author Rodney Schmaltz.
Therefore, many people who notice a mood shift in a place regularly defined as “haunted” might attribute that agitation to something supernatural. In reality, the infrasound waves are to blame.
How the study worked
The study, published this year in Frontiers in Behavioral Neuroscience, randomly assigned 36 participants to one of four groups. Each group would listen to either “calming” meditative music or “unsettling” horror-themed ambient audio. Each group would also be near hidden speakers playing infrasound between 75 and 78 decibels, a range consistent with what mechanical systems commonly produce inside buildings. These speakers were turned off and on once throughout the study.
Each participant provided saliva samples immediately before the music started and again 20 minutes later, which were analyzed to measure cortisol, the hormone the body releases under stress.
Researchers found that, regardless of which type of music they heard, the participants showed a notable increase in salivary cortisol when exposed to infrasound.
And while anecdotal, participants in the infrasound condition rated themselves as more irritable, less interested afterward, and even described the music as noticeably sadder.
Interestingly, what people didn’t seem to feel when exposed to infrasound was anxiety or fear, but rather irritability, disinterest, and a low-grade emotional discomfort…all of which correlate to a spike in cortisol.
The researcher explained that in the animal kingdom, some species (such as elephants) use it to communicate with one another over great distances. Others, like some birds, detect coming storms from infrasound.
Others still have an aversion to the discomfort it causes. Some fish have tiny stone-like organs in their inner ear that help them stay away from it and remain balanced and upright in the water.
Humans happen to have similar structures, and researchers theorize that this balance system, which connects to brain regions involved in emotion, may register infrasound without conscious awareness.
Still, given the small amount of study participants (as well as the lack of diversity, most were female undergrad students), no major conclusions can be drawn. So ghost hunters, fret not!
Whether you lean paranormal or skeptical, the science does confirm that humans are more sensitive to unseen forces than we realize, whether those forces come from vibrations in the environment or something we simply don’t yet understand. Either way, our minds and bodies seem capable of picking up signals long before we consciously recognize them.
Ever heard of “highway hypnosis”? If you never went over it in American Driver’s Ed, it’s the phenomenon during which we tend to zone out while driving on long, repetitive stretches of highway or on routes we’ve taken a thousand times. It’s that feeling of pulling into your driveway and having very little recollection of actually getting there.
Suffice it to say, going into pure autopilot mode on the road isn’t ideal. It’s not safe, and we tend to ignore important signage, like speed limits.
One high-traffic area in Wisconsin just debuted a new, eye-catching speed limit
The Outagamie County Recycling and Solid Waste facility in Appleton gets a lot of through-traffic. Big trucks, commercial haulers, and plenty of civilian cars make their way through the facility on any given day.
Keeping a low posted speed limit helps keep everyone safe. Usually, in places like this, you’d see speed limits of 15, 10, or even 5 miles per hour.
Outagamie County went in a slightly more offbeat direction: 17.3 mph. No, it’s not a typo. See for yourself:
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17.3 mph: Not a typo, not a joke
The sign isn’t just for laughs. It’s not a temporary fixture meant to get a few likes on social media or encourage people to stop for photo ops.
Its purpose is far more important: to get people to pay attention. The unusual number causes people to do a double-take. Instead of eyes glazing over at yet another 15 mph limit, the 17.3 sticks out like a sore thumb and makes drivers’ brains perk up—and hopefully, their feet ease off the gas.
Kraig Van Groll, the site’s solid waste superintendent, said the sign is working, per Supercar Blondie:
“We’ve definitely seen positive engagement and behavior changes across the site. That includes residents using the site daily, people visiting on tours, and commercial users operating here regularly. If nothing else, it’s really opened the door for more conversations around overall site safety and awareness for all users of the site.”
Jordan Hiller, recycling and solid waste program coordinator, told WBAY-TV that the sign has caused a bit of an “uproar” on social media—in a good way. People get a kick out of it, and it has ultimately done its job: drawing more attention to road safety around the facility.
Not just Wisconsin: Odd speed limits are becoming more common
While major roads and highways will probably stick with nice, round speed limits, smaller areas—shopping centers, parking lots, private facilities—are turning more and more to eye-catching numbers like Outagamie’s 17.3.
A shopping center in Colorado Springs, Colorado, features an 8.2 mph speed limit:
This speed limit sign I saw in a parking lot which is exactly 8.2 miles per hour. byu/SackJnyder inmildlyinteresting
Another user on Reddit spotted an 18 mph speed limit:
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