6 Rules for Touching Humans, Based on Science

Hugs, handshakes, butt pats: Touching among humans is, well, a touchy subject. As kids we were taught that there’s good and bad touches—and it only got more complicated from there. Nobody is immune to the vagaries and complications, either: How politicians touch—from former President George W. Bush's famous Merkel-shoulder-rub gaffe to Michelle Obama's half-embrace of the Queen—is often controversial, and there's seemingly never-ending debate in business circles about hugging vs. handshaking (and let's not even get into single- vs. double-cheek kissing). At the same time, touching is essential to human bonding, stimulating oxytocin and endorphins.

Perhaps science can sort this out? Here are some rules on the subject from research.


For a long time, it was believed that touch was the “simple sense”: that the brain, and specifically the somatosensory cortex, interpreted basic information like temperature and pressure as received by the skin—and that’s it. One 2012 study of heterosexual males showed that the brain processes touch using more cues than just physical sensation. In the study, the subjects received a "sensual caress" from an unseen hand while watching a video clip of either a woman or a man who appeared to be delivering the well-timed touch. In reality, every stroke was delivered by a woman's hand. Looking at fMRIs of the men's brain activity, researchers saw that their somatosensory cortex responded more significantly to what they believed was the woman’s touch than to the man’s. So that “simple” part of the brain wasn’t just interpreting physical cues, but was also accounting for cultural and emotional information. As far as the brain was concerned, those aspects of touch were inseparable from physical stimulation. 


A study published recently in PNAS determined that it’s the closeness of the relationship, rather than frequency of seeing a person, that determined how acceptable intimate touch was—which surprised researchers, until they realized why. Lead author Robin Dunbar, of the Department of Experimental Psychology at Oxford, tells mental_floss that the results make sense when you consider that “what is important in a relationship is how you feel about the person. The frequency of contact is simply the vehicle to achieve that, not the thing itself,” he says.


In a 2006 study [PDF] that involved participants in the United States and Spain, random pairs of strangers were separated, with just a black curtain between them. One was given the task of communicating an emotion by touching the other person’s hand or arm. Researchers found that the people being touched “could decode anger, fear, disgust, love, gratitude, and sympathy via touch at much-better-than-chance levels." Another study by the same researchers found that people could accurately decode distinct emotions by merely watching others communicate by touching each other. In short, touch gave just as much information as tone of voice or facial expression.


Naturally, this is not permission for anyone to touch women more (I’m talking to you, creepy subway guy and inappropriate co-worker), but according to Dunbar’s PNAS study (see #2), women are—in general—both more comfortable being touched and more likely to touch others. This touchiness appears to cement deeper connections: "participants reported feeling stronger emotional bonds with female than male members of their social networks," according to the study.  


The same study also found that the rules of touch don’t vary as much as we think. While his study only looked at European countries, the expected differences between, for example, Finns and Italians—traditionally thought to be on either side of a great European touch divide, with northern cultures hands-off and Mediterranean cultures hands-on—was smaller than anticipated, suggesting the basics of touch are less of a cultural artifact than we might assume. 


Touching others is just fundamentally confusing: “…we are always caught between two things—that we express closeness by more touch and that we try to use touch to express more closeness (when it doesn't exist but we would like it to). So it is always a bit risky, and that is why people get into trouble,” Dunbar tells mental_floss. His best advice for reaching out? “Be careful! Read the signals first!” Perhaps we should update the old school rule: Until you know what's acceptable, keep your hands to yourself. 

Keith Holmes/Hakai Institute
Ice Age Human Footprints in Canada Reveal a Walk on the Beach Taken 13,000 Years Ago
Calvert Island
Calvert Island
Keith Holmes/Hakai Institute

The prehistoric mariners rowed their canoe into a secluded channel and then onto the island's sandy beach, just above the high-tide mark. One person got out of the boat and stood for a moment, facing northwest. Others, including another barefoot adult and child, followed the leader and walked toward higher, drier land.

Today, roughly 13,000 years later, their footprints have been preserved in a layer of sediment and confirmed to date from the last ice age. The discovery, on Calvert Island on the central coast of British Columbia, Canada, adds to the growing body of evidence that suggests ancient humans crossed from Asia to North America and traveled south along the Pacific shoreline.

"This finding provides evidence of the seafaring people who inhabited this area during the tail end of the last major ice age," said University of Victoria anthropologist Duncan McLaren, lead author of the new study in the journal PLOS One, in a statement.

Archaeologists on Calvert Island, British Columbia, Canada
Researchers Daryl Fedje (left) and Duncan McLaren (right) dig at the Calvert Island site.
Grant Callegari/Hakai Institute

Most anthropologists believe that early peoples migrated from Asia to North America across Beringia, the region where Russia's Chukchi Peninsula and Alaska face each other across the Bering Strait. Then the migrants took two possible routes. One popular theory, proposed in the 1930s, suggests people traveled south along an ice-free corridor that lay on the eastern slope of the Rocky Mountains where two colossal ice sheets split from one other. A more recent theory proposes that they sailed along a coastal route from Alaska to Washington State.

The coastal route lies within the territories of the Heiltsuk First Nation and Wuikinuxv First Nation. Their oral histories describe how the scattered islands between the open ocean and the edge of the ice sheet remained unglaciated. On these refuges, their ancestors subsisted on the abundant fish, shellfish, and marine mammals and likely used watercraft to travel between the islands. "Heiltsuk oral history talks about our people living in our territory before the ice age, and talks about the physical features of the landscape that our people witnessed change over time due to the ice, which influenced things like place names in our territory," William Housty, chair of the Heiltsuk Integrated Resource Management Department board of directors, tells Mental Floss.

Archaeological evidence affirming the histories is scarce, in part because few researchers have focused on the area. In 2014, McLaren and colleagues from the University of Victoria and the Hakai Institute, along with representatives of the First Nations, began combing the beach at a Calvert Island site called EjTa-4 for sediments dating back to the late Pleistocene epoch (also known as the Ice Age, which ended 11,700 years ago). Back then, the sea level around Calvert Island was 6.5 to 10 feet lower than it is today, so the team concentrated on the intertidal zone. After probing several test holes, they found what appeared to be footprints near the base of a huge shell midden.

A 13,000-year-old human footprint on Calvert Island, British Columbia, Canada
A photo of Track #17 beside a digitally enhanced image of the same feature. Note the toe impressions and arch, which indicate that this is a right footprint.
Duncan McLaren

Over the next three field seasons, they continued to excavate a 6.5-foot-by-13-foot pit, removing strata of sand, pebbles, and organic matter before striking the layer of clay. "The site was below the high-tide water line, so we only had one day from the time we opened the last layer. When the high tide came up it would wash everything away," Jennifer Walkus, the research liaison between the Wuikinuxv Nation and Hakai Institute, tells Mental Floss. "We had an idea from the test pit the previous year that there might be footprints, so we knew that day was going to be busy. It was amazing as the last layer was pulled up and the measurements were taken."

In the substrate, the team found 29 individual human tracks, darkened by time, left by at least three different people—two adults and a child—based on the dimensions of the individual prints. "The fact that they were footprints was more and more obvious as the measurements came in and there were three lengths," Wallkus says. The orientation of some of the tracks at the ancient shoreline indicated that a group of people may have disembarked from a watercraft and walked northwest, toward higher ground, with their backs to the prevailing wind.

Researchers also collected samples of clay and fragments of shore pine from the sand underneath the prints. Radiocarbon dating confirmed that the pine bits, and the footprints, were between 13,317 and 12,633 years old.

"I can't speak for the Nation as a whole, but for me, it's a validation of the fact that we have been here for much longer than the previous narrative," Walkus says. "The fact that these footprints put people in the vicinity in the time of glacial recession underlines that our legends are grounded in living in our area over huge spans of time."

When William Housty, who was not present at the dig, heard of the discovery, "I immediately started to think about our first ancestors and the stories of their origin," he says. "I also thought that, once again, science [and] archeology have confirmed what our oral history has been telling us all along."

University of York
UK Archaeologists Have Found One of the World’s Oldest 'Crayons'
University of York
University of York

A prehistoric chunk of pigment found near an ancient lake in England may be one of the world's oldest crayons, Colossal reports. The small object made of red ochre was discovered during an archaeological excavation near Lake Flixton, a prehistoric lake that has since become a peat wetland but was once occupied by Mesolithic hunter-gatherers. Though it’s hard to date the crayon itself, it was found in a layer of earth dating back to the 7th millennium BCE, according to a recent study by University of York archaeologists.

Measuring less than an inch long, the piece of pigment is sharpened at one end, and its shape indicates that it was modified by a person and used extensively as a tool, not shaped by nature. The piece "looks exactly like a crayon," study author Andy Needham of the University of York said in a press release.

A pebble of red ochre thought to be a prehistoric crayon
University of York

The fine grooves and striations on the crayon suggest that it was used as a drawing tool, and indicate that it might have been rubbed against a granular surface (like a rock). Other research has found that ochre was collected and used widely by prehistoric hunter-gatherers like the ones who lived near Lake Flixton, bolstering the theory that it was used as a tool.

The researchers also found another, pebble-shaped fragment of red ochre at a nearby site, which was scraped so heavily that it became concave, indicating that it might have been used to extract the pigment as a red powder.

"The pebble and crayon were located in an area already rich in art," Needham said. "It is possible there could have been an artistic use for these objects, perhaps for coloring animal skins or for use in decorative artwork."

[h/t Colossal]


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