Tuesday, December 4, 2018

Your past is calling: Can you ID stone toolmaking 'ring' tones?

Emory anthropologist Dietrich Stout invites you to participate in an online experiment, Sounds of the Past, investigating the human ability to discriminate and interpret the sounds produced by stone toolmaking. (Photo by Ann Watson, Emory Photo/Video)

By Carol Clark

Long before everyone started carrying a smart phone everywhere they went — attuned to the sounds of a text, call or email — our ancestors carried a hand axe.

“Stone tools were the key human technology for two million years,” says Dietrich Stout, director of the Paleolithic Technology Laboratory at Emory University. In fact, he adds, the process of making them may have played an important role in our ability to communicate.

If you can spare just 10 minutes for science, you can use your smart phone and a pair of headphones to log onto a web site to help Stout test whether ancient tool-making promoted special acoustic abilities — perhaps even honing the development of spoken language.

Stout is an experimental archeologist who recreates prehistoric stone toolmaking, known as knapping, to study the evolution of the human brain and mind. In many of his experiments, subjects actually bang out the tools as activity in their brains is recorded via functional magnetic resonance imaging (fMRI). He’s already found evidence that the visual-spatial skills used in knapping activate areas of the brain that are involved in language processing.

But what about the sounds of knapping?

“An experienced knapper once told me that he would rather be blindfolded than wear ear plugs while making a stone tool, because he got so much valuable information out of the sound when he struck the stone,” Stout says. “That got me wondering: Do knappers just think that the sounds are giving them meaningful information? Could we give them a test to find out if that’s true?”

Stout teamed up with Robert Rein, from the German Sport University Cologne, to develop just such a test. The result is the online experiment Sounds of the Past, open to everyone — from expert knappers to those who have never knapped at all.


During stone tool production a stone flake is produced by hitting a stone core with another stone, used like a hammer. Factors like the geometry of the core stone and the location and the strength of the strike determine the size of the flake that falls off.

The researchers recorded the sounds of flakes breaking off during stone tool production. Participants in the online experiment are presented with a series of these sounds, with no accompanying visuals, and asked to estimate the length of the flakes produced, within a range of parameters.

Participants are also asked whether they have prior experience knapping. The aim is to get as many experienced knappers as possible to participate, and at least an equal number of those without experience, then compare the results.

“No one is going to guess all the flake sizes, to the millimeter,” Stout says. “But if we plot out the results, we should see if there is a correlation between the level of accuracy and whether someone is an experienced or novice knapper.”

The study is self-funded and does not provide compensation for participants. Individual test results are also not available. “It’s really something that we hope participants will just have fun doing, along with the satisfaction that they are providing data to help us understand the evolution of the human brain,” Stout says.

The length of time the experiment will be available is open ended, he adds, although the researchers hope to have enough results in hand for analysis sometime next year.

Click here to participate in the experiment.

Related:
Complex cognition shaped the Stone Age hand axe
Brain trumps hand in Stone Age tool study

Learn ethnobotany while making holiday gifts



What does an ethnobotanist give for presents during the holidays? If you’re Cassandra Quave, you enlist your kids to help you make herbal-infused, bees-wax chapstick from scratch. Marigold, cinnamon, nutmeg and black pepper are just a few of the ingredients.

Quave is an assistant professor in Emory’s Center for the Study of Human Health and in the School of Medicine’s Department of Dermatology. Her specialty of ethnobotany takes her around the world, studying how traditional healers use plants. She’s particularly interested in plants for treating skin infections and wounds. She collects the plants, extracts their chemical compounds, and tests them for efficacy in combating antibiotic-resistant infections.

Watch Quave’s latest video on her TeachEthnobotany YouTube channel to learn how to make your own botanical chapstick. And check out some of her other videos. She’ll take you to a traditional market in Kuwait to learn about dates, and to the Atlanta Botanical Garden for the backstory of “the vine of the soul.”

Related:
The Plant Hunters
Invasive weed packs power to knock out antibiotic-resistant bacteria
Her patient approach to health

Thursday, November 8, 2018

'Potato gene' reveals how ancient Andeans adapted to starchy diet

A woman sells potatoes at a market in the Andes. DNA analyses show that ancient populations of the Peruvian highlands adapted to the introduction of agriculture in ways distinct from other global populations. 

By Carol Clark

Potatoes, native to South America, became an agricultural crop thousands of years ago in the Andean highlands of Peru. And just as the ancient Andean people turned wild tubers into the domesticated potato, the potato may have altered the genomes of the Andeans who made it a staple of their diet.

Science Advances published the findings. DNA analyses show that ancient populations of the Peruvian highlands adapted to the introduction of agriculture and an extreme, high-altitude environment in ways distinct from other global populations.

“We see a different configuration of a gene associated with starch digestion in the small intestine — MGAM — in the agricultural ancient Andean genome samples, but not in hunter-gatherers down the coast,” says Emory University geneticist John Lindo, first author of the paper. “It suggests a sort of co-evolution between an agricultural crop and human beings.”

In contrast, European populations that began consuming more grains with the rise of agriculture show different genomic changes. Research has shown that their genomes have an increased number of copies of the gene coding for amylase — an enzyme in saliva that breaks down starch.

Lindo, an assistant professor of anthropology at Emory, integrates the approaches of ancient whole genomes, statistical modeling and functional methods into ancient DNA research. The international team of 17 researchers also included Anna Di Rienzo of the University of Chicago (who specializes in physiology and genetics) and high-altitude archeologists Mark Aldenderfer, from the University of California, Merced, and Randall Haas, from the University of California, Davis.

The study looked at seven ancient whole genomes from the Lake Titicaca region of the Andean highlands of Peru, dating back from 1,800 to 7,000 years. The researchers also compared the ancient whole genomes with 64 modern-day genomes from both highland Andean populations and lowland populations in Chile, to identify genetic adaptions that took place before the arrival of Europeans in the 1500s.

The hardy potato helped people adapt to the harsh environment of the Andean highlands.

The Andean highlands make an ideal natural laboratory for ancient DNA studies, due to the strong selective pressure needed for ancient populations to adapt to altitudes greater than 2,500 meters. “Frigid temperatures, low oxygen levels and intense ultraviolet radiation make the highlands one of the most extreme environments that human beings have occupied,” Lindo says. “It provides a glimpse of our potential for adaptability.”

Both the ancient and modern high-altitude populations showed strong positive selection on variants in the MGAM gene, which is evident by at least 1,800 years ago. That fits with archeological evidence indicating that the domesticated potato — a crop resistant to cold that grows mainly underground — became a staple of the Peruvian highlands as far back as 3,400 years ago.

The researchers also discovered that the Andean highland population’s genomes do not share the same genetic changes previously seen in Tibetan genomes in response to hypoxia, or low levels of oxygen. That suggests that the Andean genomes adapted to high altitude in different ways.

One possibility uncovered in the study is differentiation in the DST gene, which has been linked to proper cardiac muscle in mice. DST histone modifications in the Andean genomes associated with blood and the right ventricle of the heart may correlate to the tendency of Andean highlanders to have enlarged right ventricles. That finding fits with a previous study suggesting that Andeans may have adapted to high altitude hypoxia via cardiovascular modifications.

A gene flow analysis found that the low- and high-elevation populations split between 8,200 to 9,200 years ago.

The arrival of the Spanish in South America — who brought new diseases, along with social disruption and war — coincided with an estimated reduction of 90 percent of the total Andean population. The current analysis, however, showed that the effective breeding population in the highlands went down by only 27 percent.

“We found a very strong selection in the highlands population on an immune gene that has been correlated with smallpox, which may have had a protective effect,” Lindo says. The harsh environment of the highlands, he adds, may have also buffered them from the devastation seen in the lowlands.

“Understanding the diet, environment and historical events of various ancestries, and how those ancestries adapted to these factors, may be one way to understand some health disparities among different populations,” Lindo says.

Related:
DNA analysis adds twist to ancient story of a Native American group
Malawi yields oldest-known human DNA from Africa

Photos: Getty Images

Tuesday, October 23, 2018

Schadenfreude sheds light on the darker side of humanity


“We all experience schadenfreude but we don’t like to think about it too much because it shows how ambivalent we can be to our fellow humans,” says Emory psychologist Philippe Rochat.

By Carol Clark

Schadenfreude, the sense of pleasure people derive from the misfortune of others, is a familiar feeling to many — perhaps especially during these times of pervasive social media.

This common, yet poorly understood, emotion may provide a valuable window into the darker side of humanity, finds a review article by psychologists at Emory University. New Ideas in Psychology published the review, which drew upon evidence from three decades of social, developmental, personality and clinical research to devise a novel framework to systematically explain schadenfreude.

The authors propose that schadenfreude comprises three separable but interrelated subforms — aggression, rivalry and justice — which have distinct developmental origins and personality correlates.

They also singled out a commonality underlying these subforms.

“Dehumanization appears to be at the core of schadenfreude,” says Shensheng Wang, a PhD candidate in psychology at Emory and first author of the paper. “The scenarios that elicit schadenfreude, such as intergroup conflicts, tend to also promote dehumanization.”

Co-authors of the study are Emory psychology professors Philippe Rochat, who studies infant and child development, and Scott Lilienfeld, whose research focuses on personality and personality disorders.

Dehumanization is the process of perceiving a person or social group as lacking the attributes that define what it means to be human. It can range from subtle forms, such as assuming that someone from another ethnic group does not feel the full range of emotions as one’s in-group members do, all the way to blatant forms — such as equating sex offenders to animals. Individuals who regularly dehumanize others may have a disposition towards it. Dehumanization can also be situational, such as soldiers dehumanizing the enemy during a battle.

“Our literature review strongly suggests that the propensity to experience schadenfreude isn’t entirely unique, but that it overlaps substantially with several other ‘dark’ personality traits, such as sadism, narcissism and psychopathy,” Lilienfeld says. “Moreover, different subforms of schadenfreude may relate somewhat differently to these often malevolent traits.”

One problem with studying the phenomenon is the lack of an agreed definition of schadenfreude, which literally means “harm joy” in German. Since ancient times, some scholars have condemned schadenfreude as malicious, while others have perceived it as morally neutral or even virtuous.

“Schadenfreude is an uncanny emotion that is difficult to assimilate,” Rochat says. “It’s kind of a warm-cold experience that is associated with a sense of guilt. It can make you feel odd to experience pleasure when hearing about bad things happening to someone else.”

Psychologists view schadenfreude through the lens of three theories. Envy theory focuses on a concern for self-evaluation, and a lessening of painful feelings when someone perceived as enviable gets knocked down a peg. Deservingness theory links schadenfreude to a concern for social justice and the feeling that someone dealt a misfortune received what was coming to them. Intergroup-conflict theory concerns social identity and the schadenfreude experienced after the defeat of members of a rival group, such as during sporting or political competitions.

The authors of the current article wanted to explore how all these different facets of schadenfreude are interrelated, how they differ, and how they can arise in response to these concerns.

Their review delved into the primordial role of these concerns demonstrated in developmental studies. Research suggests that infants as young as eight months demonstrate a sophisticated sense of social justice. In experiments, they showed a preference for puppets who assisted a helpful puppet, and who punished puppets that had exhibited antisocial behavior. Research on infants also points to the early roots of intergroup aggression, showing that, by nine months, infants preferred puppets who punish others who are unlike themselves.

“When you think of normal child development, you think of children becoming good natured and sociable,” Rochat says. “But there’s a dark side to becoming socialized. You create friends and other in-groups to the exclusion of others.”

Spiteful rivalry appears by at least age five or six, when research has shown that children will sometimes opt to maximize their gain over another child, even if they have to sacrifice a resource to do so.

By the time they reach adulthood, many people have learned to hide any tendencies for making a sacrifice just for spite, but they may be more open about making sacrifices that are considered pro-social.

The review article posits a unifying, motivational theory: Concerns of self-evaluation, social identity and justice are the three motivators that drive people toward schadenfreude. What pulls people away from schadenfreude is the ability to feel empathy for others and to perceive them as fully human and to show empathy for them.

Ordinary people may temporarily lose empathy for others. But those with certain personality disorders and associated traits — such as psychopathy, narcissism or sadism — are either less able or less motivated to put themselves in the shoes of others.

“By broadening the perspective of schadenfreude, and connecting all of the related phenomena underlying it, we hope we’ve provided a framework to gain deeper insights into this complex, multi-faceted emotion,” Wang says.

“We all experience schadenfreude but we don’t like to think about it too much because it shows how ambivalent we can be to our fellow humans,” Rochat says. “But schadenfreude points to our ingrained concerns and it’s important to study it in a systematic way if we want to understand human nature.”

Related:
What is a psychopath?
Sharing ideas about the concept of fairness

Monday, October 22, 2018

Study gives new insight into how the brain perceives places

Example of an image from the fMRI study. Participants were asked to imagine they were standing in the room and indicate through a button press whether it was a bedroom, a kitchen or a living room. On separate trials, they were asked to imagine that they were walking on the continuous path through the room and indicate which door they could leave through. (Image by Andrew Persichetti)

By Carol Clark

Nearly 30 years ago, scientists demonstrated that visually recognizing an object, such as a cup, and performing a visually guided action, such as picking the cup up, involved distinct neural processes, located in different areas of the brain. A new study shows that the same is true for how the brain perceives our environment — it has two distinct systems, one for recognizing a place and another for navigating through it.

The Journal of Neuroscience published the finding by researchers at Emory University, based on experiments using functional magnetic resonance imaging (fMRI). The results showed that the brain’s parahippocampal place area responded more strongly to a scene recognition task while the occipital place area responded more to a navigation task.

The work could have important implications for helping people to recover from brain injuries and for the design of computer vision systems, such as self-driving cars.

“It’s thrilling to learn what different regions of the brain are doing,” says Daniel Dilks, senior author of the study and an assistant professor of psychology at Emory. “Learning how the mind makes sense of all the information that we’re bombarded with every day is one of the greatest of intellectual quests. It’s about understanding what makes us human.”

Entering a place and recognizing where you are — whether it’s a kitchen, a bedroom or a garden — occurs instantaneously and you can almost simultaneously make your way around it.

“People assumed that these two brain functions were jumbled up together — that recognizing a place was always navigationally relevant,” says first author Andrew Persichetti, who worked on the study as an Emory graduate student. “We showed that’s not true, that our brain has dedicated and dissociable systems for each of these tasks. It’s remarkable that the closer we look at the brain the more specialized systems we find — our brains have evolved to be super efficient.”

Persichetti, who has since received his PhD from Emory and now works at the National Institute of Mental Health, explains that an interest in philosophy led him to neuroscience. “Immanuel Kant made it clear that if we can’t understand the structure of our mind, the structure of knowledge, we’re not going to fully understand ourselves, or even a lot about the outside world, because that gets filtered through our perceptual and cognitive processes,” he says.

The Dilks lab focuses on mapping how the visual cortex is functionally organized. “We are visual creatures and the majority of the brain is related to processing visual information, one way or another,” Dilks says.

Researchers have wondered since the late 1800s why people suffering from brain damage sometimes experience strange visual consequences. For example, someone might have normal visual function in all ways except for the ability to recognize faces.

It was not until 1992, however, that David Milner and Melvyn Goodale came out with an influential paper delineating two distinct visual systems in the brain. The ventral stream, or the temporal lobe, is involved in object recognition and the dorsal stream, or the parietal lobe, guides an action related to the object.

In 1997, MIT’s Nancy Kanwisher and colleagues demonstrated that a region of the brain is specialized in face perception — the fusiform face area, or FFA. Just a year later, Kanwisher’s lab delineated a neural region specialized in processing places, the parahippocampal place area (PPA), located in the ventral stream.

While working as a post-doctoral fellow in the Kanwisher lab, Dilks led the finding of a second region of the brain specialized in processing places, the occipital place area, or OPA, located in the temporal stream.

Dilks set up his own lab at Emory the same year that discovery was published, in 2013. Among the first questions he wanted to tackle was why the brain had two regions dedicated to processing places.

Persichetti designed an experiment to test the hypothesis that place processing was divided in the brain in a manner similar to object processing. Using software from the SIMS life simulation game, he created three digital images of places: A bedroom, a kitchen and a living room. Each room had a path leading through it and out one of three doors. Study participants in the fMRI scanner were asked to fixate their gaze on a tiny white cross. On each trial, an image of one of the rooms then appeared, centered behind the cross. Participants were asked to imagine they were standing in the room and indicate through a button press whether it was a bedroom, a kitchen or a living room. On separate trials, the same participants were also asked to imagine that they were walking on the continuous path through the exact same room and indicate whether they could leave through the door on the left, in the center, or on the right.

The resulting data showed that the two brain regions were selectively activated depending on the task: The PPA responded more strongly to the recognition task while the OPA responded more strongly to the navigation task.

“While it’s incredible that we can show that different parts of the cortex are responsible for different functions, it’s only the tip of the iceberg,” Dilks says. “Now that we understand what these areas of the brain are doing we want to know precisely how they’re doing it and why they’re organized this way.”

Dilks plans to run causal tests on the two scene-processing areas. Repetitive transcranial magnetic stimulation, or rTMS, is a non-invasive technology that can be attached to the scalp to temporarily deactivate the OPA in healthy participants and test whether someone can navigate without it.

The same technology cannot be used to deactivate the PPA, due to its deeper location in the temporal lobe. The Dilks lab plans to recruit participants suffering brain injury to the PPA region to test for any effects on their ability to recognize scenes.

Clinical applications for the research include more precise guidance for surgeons who operate on the brain and better brain rehabilitation methods.

“My ultimate goal is to reverse-engineer the human brain’s visual processes and replicate it in a computer vision system,” Dilks says. “In addition to improving robotic systems, a computer model could help us to more fully understand the human mind and brain.”

Related:
How babies see faces: New fMRI technology opens window onto infants' minds