Category: Press releases

Do you have a sweet tooth? Honeybees have a sweet claw

Selected coverage: Discovery News, Yahoo, Süddeutsche Zeitung, RedOrbit

New research on the ability of honeybees to taste with claws on their forelegs reveals details on how this information is processed, according to a study published in the open-access journal, Frontiers in Behavioral Neuroscience.

Insects taste through sensilla, hair-like structures on the body that contain receptor nerve cells, each of which is sensitive to a particular substance. In many insects, for example the honeybee, sensilla are found on the mouthparts, antenna and the tarsi – the end part of the legs. Honeybees weigh information from both front tarsi to decide whether to feed, finds the latest study led by Dr. Gabriela de Brito Sanchez, researcher, University of Toulouse, and Dr. Martin Giurfa, Director of the Research Centre on Animal Cognition, University of Toulouse, France.

Hundreds of honeybees were included in the study. Sugary, bitter and salty solutions were applied to the tarsi of the forelegs to test if this stimulated the bees to extend or retract their tongue – reflex actions that indicate whether or not they like the taste and are preparing to drink. Results revealed that honeybee tarsi are highly sensitive to sugar: even dilute sucrose solutions prompted the bees to extend their tongue. Measurements of nerve cell activity showed that the part of the honeybee tarsus most sensitive to sugary tastes is the double claw at its end. Also, the segments of the tarsus before the claws, known as the tarsomeres, were found to be highly sensitive to saline solutions.

“Honeybees rely on their color vision, memory, and sense of smell and taste to find nectar and pollen in the ever-changing environment around the colony,” says Dr. Giurfa. “The high sensitivity to salts of the tarsomeres and to sugar of the tarsal claws is impressive given that each tarsus has fewer sensilla than the other sense organs. The claw’s sense of taste allows workers to detect nectar immediately when they land on flowers. Also, bees hovering over water ponds can promptly detect the presence of salts in water through the tarsomeres of their hanging legs.”

But what if honeybees receive contradictory information, for example, about tasty sucrose from the right foreleg, but about water or distasteful caffeine from the left? The central nervous system of honeybees weighs this information from both sides, but unequally: input from the side that is first to taste something tasty or distasteful counts for more. For example, if a bee first tasted sucrose on one side, she would typically extend her tongue and subsequently ignore less attractive tastes on the other. But if the order was reversed, she was around 50% less likely than normally to extend her tongue for sucrose.

EurekAlert! PR: http://www.eurekalert.org/pub_releases/2014-02/f-dyh013114.php

Study: http://journal.frontiersin.org/article/10.3389/fnbeh.2014.00025/full

Much room for improvement in access to preventive dental care in the USA

Selected coverage: Medical Daily, WebMD

The uptake rate of preventative dental care increased over a ten-year period in the United States, but there remains a large disparity among ethnic groups, reports one of the largest and most comprehensive studies on the subject, published in the open-access journal Frontiers in Public Health.

Neglect of dental care can have serious consequences like decay, inflammation, and loss of teeth, and an increased risk of malnutrition. Gum disease has been implicated in an increased risk of cardiovascular and respiratory disease. Easy access to affordable preventive dental care – in the form of regular checkups and cleanings by dentists or dental hygienists – can help to improve the quality of life of a population.

Oral health is particularly important in a rapidly aging population, because middle-aged and older people are more likely to develop chronic conditions and complications. Yet few studies have focused on the dental health-practices of older persons.

In a new study, Professor Bei Wu, Director for International Research at Duke University’s School of Nursing, and her colleagues analyzed self-reported oral health behaviors of almost 650,000 middle-aged and elderly Americans in a phone survey conducted between 1999 to 2008 by the National Center for Statistics and Prevention. This study is the first to compare dental care between Caucasians, Hispanics, African Americans, Asian Americans, and Native Americans.

Respondents were asked when they last had their teeth cleaned by a professional, because dental cleaning is a commonly used indicator of access to dental services. They were also asked about their gender, age, marital status, income, education, ethnicity, weight, general health, number of teeth removed, and drinking and smoking habits.

Results show that the number of people who received preventive dental care underwent a slight yearly increase in all five ethnic groups. But there is a long way to go, as 23% to 43% of Americans received no preventive dental care in 2008, depending on ethnicity.

Key findings include:

  • People with health insurance were 138% more likely to receive preventive dental care.
  • Women were 33% more likely to receive preventive dental care than men.
  • 77% of Asian Americans and 76% of Caucasians reported receiving preventive dental care in 2008. Hispanics, Native Americans, and African Americans, were significantly less likely (62%, 62%, and 57% of interviewees, respectively) to receive preventive dental care.
  • Differences between Caucasians and other ethnic groups (except African Americans) in access to preventive dental care can be explained by socioeconomic differences such as income, education, and having health insurance.
  • African Americans’ reduced access to preventive dental health might be due to an insufficient number of culturally competent dental care professionals, and to a lack of awareness of oral health and dental care services within this ethnic group.
  • Many Native Americans in reservations receive inadequate dental care, partly because not enough dental care professionals are motivated to work for the Indian Health Services.
  • Smokers were less likely to receive preventive dental health care. This is of particular concern since oral health is negatively affected by tobacco use.

The researchers conclude that it is imperative to develop public dental health programs that target middle-aged and elderly Americans, improve dental care access, and to train a dental workforce that is culturally competent

Domestication of dogs may have elaborated on a pre-existing capacity of wolves to learn from humans

Selected coverage: Wiener Zeitung, Huffington Post, Tribune de Genève, RedOrbit, ABC News

Wolves can learn from observing humans and pack members where food is hidden and recognize when humans only pretend to hide food, reports a study for the first time in the open-access journal Frontiers in Psychology. These findings imply that when our ancestors started to domesticate dogs, they could have built on a pre-existing ability of wolves to learn from others, not necessarily pack members.

A paper published recently in the journal Science suggested that humans domesticated dogs about 18 thousand years ago, possibly from a European population of grey wolves that is now extinct. But it remains unknown how much the ability of dogs to communicate with people derives from pre-existing social skills of their wolf ancestors, rather than from novel traits that arose during domestication.

In a recent study, Friederike Range and Zsófia Virányi from the Messerli Research Institute at the University of Veterinary Medicine Vienna investigated if wolves and dogs can observe a familiar “demonstrator” – a human or a specially trained dog – to learn where to look for food within a meadow. The subjects were 11 North American grey wolves and 14 mutts, all between 5 and 7 months old, born in captivity, bottle-fed, and hand-raised in packs at the Wolf Science Center of Game Park Ernstbrunn, Austria.

The wolves and dogs were two to four times more likely to find the snack after watching a human or dog demonstrator hide it, and this implies that they had learnt from the demonstration instead of only relying on their sense of smell. Moreover, they rarely looked for the food when the human demonstrator had only pretended to hide it, and this proves that they had watched very carefully.

The wolves were less likely to follow dog demonstrators to hidden food. This does not necessarily mean that they were not paying attention to dog demonstrators: on the contrary, the wolves may have been perceptive enough to notice that the demonstrator dogs did not find the food reward particularly tasty themselves, and so simply did not bother to look for it.

The researchers conclude that the ability to learn from other species, including humans, is not unique to dogs but was already present in their wolf ancestors. Prehistoric humans and the ancestors of dogs could build on this ability to better coordinate their actions.

EurekAlert! PR: http://www.eurekalert.org/pub_releases/2013-12/f-dod120213.php

Study: http://journal.frontiersin.org/article/10.3389/fpsyg.2013.00868/full

A longitudinal study of grapheme-color synaesthesia in childhood

What colour is H? Is 4 brighter than 9? For most people these questions might seem baffling, but not for people with grapheme-color synesthesia.
In the first long-term childhood study on grapheme-color synesthesia, researchers followed 80 children to determine when and how associations between graphemes and colors develop. The latest results are published in the open-access journal Frontiers in Human Neuroscience.

Grapheme-color synesthesia is a harmless, alternative form of perception caused by subtle differences in the brain – possibly, stronger connections between centers for language and color – that give letters and numbers their phantom colors. It is passed down from parent to child in around 1 to 2% of the population.

In the present study, a group of synesthete children was tested three times between 6 and 10 years old. Each child was presented with 36 graphemes – the letters A to Z and digits 0 to 9 – and asked to choose the ‘best’ of 13 colors for each.

Children with grapheme-color synesthesia had already developed strong associations for around 30% of graphemes at 6 years old. At 7 years old, the same children had associations for around 50% of graphemes, and this increased to 70% of graphemes at 10 years old. The synesthete children were consistent in their choices over this 4-year period. Three children who were synesthetes at ages 6 to 7 were no longer so at 10 years old, indicating that the condition spontaneously disappears in some children as they grow older.
“This repeated testing of child synesthetes in real time allowed us to see for the first time that synesthetic colours emerge slowly during childhood, building up an incremental inventory of colorful letters and numbers,” says Dr. Simner, a cognitive neuropsychologist who specializes in synesthesia, from the University of Edinburgh, UK.

The researchers’ next challenge is to determine how changes in the intensity of synesthesia – as strengthening or loss with increasing age – can be explained from changes in the organization of the brain.

EurekAlert! PR: http://www.eurekalert.org/pub_releases/2013-11/f-als111113.php

Study: http://journal.frontiersin.org/article/10.3389/fnhum.2013.00603/full

Empathy helps children to understand sarcasm

The greater the empathy skills of children, the easier it is for them to recognize sarcasm, according to a new study in the open-access journal Frontiers in Psychology.

For children, sarcastic language can be difficult to understand. They generally begin to recognize sarcasm between ages 6 and 8, especially familiar sarcastic praise such as “Thanks a lot!” and “Nice going!” But some children take much longer to begin to understand sarcasm, with detection improving even through adolescence.

In a new study, Penny Pexman, Juanita Whalen, and Andrew Nicholson investigated whether differences in the ability of children to empathize with others might help to explain why.
The researchers looked at empathy specifically because they thought that in order to understand sarcasm children must be able to adopt the perspective of the speaker – to understand the speaker’s attitude and emotions.

The study involved 31 children between 8 and 9 years old in a task that required them to recognize sarcasm. After children watched a series of puppet shows that included either sarcastic or non-sarcastic praise, they were asked to pick up a “mean” toy shark if they believed that the puppets had spoken sarcastically, or a “nice” duck otherwise. Each child was tested 12 times, with different puppets and scenarios. The empathy skills of the children were measured separately.

Children detected the puppets’ sarcasm about half of the time, and children with relatively strong empathy skills did so more accurately. Children with stronger empathy skills were nearly twice as accurate as children with less advanced empathy skills. Initially, the researchers analyzed a group of 6-7 year olds, but this age group revealed almost zero accuracy for sarcasm.

The researchers also quantified children’s eye gaze and reaction time during the sarcasm recognition task, to quantify subtle clues about their understanding. They measured whether the children looked towards the duck or the shark, as well as the time it took them to choose either. This gave more subtle clues about the children’s understanding.

“Sarcastic language, especially in unfamiliar forms, is a real challenge for most children,” explains Prof. Pexman. “Even when children did not recognize a remark as sarcastic, there was evidence in their reactions that the children with stronger empathy skills were sensitive to the speaker’s intent.”

“This study helps us understand why some children deal better with this challenge than others and provides new insights about development of this complex aspect of emotion recognition,” adds Pexman. “It also puts us in a better position to help children who are struggling with this challenge”.

EurekAlert! PR: http://www.eurekalert.org/pub_releases/2013-10/f-ehc100313.php

Study: http://journal.frontiersin.org/article/10.3389/fpsyg.2013.00691/full

New fossils push the origin of flowering plants back by 100 million years to the early Triassic

Selected coverage: Science Magazine, Der Spiegel, BBC, NBC, Discovery News, The Independent

Drilling cores from Switzerland have revealed the oldest known fossils of the direct ancestors of flowering plants. These beautifully preserved 240-million-year-old pollen grains are evidence that flowering plants evolved 100 million years earlier than previously thought, according to a new study in the open-access journal Frontiers in Plant Science.

Flowering plants evolved from extinct plants related to conifers, ginkgos, cycads, and seed ferns. The oldest known fossils from flowering plants are pollen grains. These are small, robust and numerous and therefore fossilize more easily than leaves and flowers.

An uninterrupted sequence of fossilized pollen from flowers begins in the Early Cretaceous, approximately 140 million years ago, and it is generally assumed that flowering plants first evolved around that time. But the present study documents flowering plant-like pollen that is 100 million years older, implying that flowering plants may have originated in the Early Triassic (between 252 to 247 million years ago) or even earlier.

Many studies have tried to estimate the age of flowering plants from molecular data, but so far no consensus has been reached. Depending on dataset and method, these estimates range from the Triassic to the Cretaceous. Molecular estimates typically need to be “anchored” in fossil evidence, but extremely old fossils were not available for flowering plants. That is why the present finding of flower-like pollen from the Triassic is significant, according to the team of researchers who made the discovery.

Peter Hochuli and Susanne Feist-Burkhardt from the University of Zürich studied two drilling cores from Weiach and Leuggern, northern Switzerland, and found pollen grains that resemble fossil pollen from the earliest known flowering plants. With Confocal Laser Scanning Microscopy, they obtained high-resolution images across three dimensions of six different types of pollen.

In a previous study from 2004, Hochuli and Feist-Burkhardt documented different, but clearly related flowering-plant-like pollen from the Middle Triassic in cores from the Barents Sea, south of Spitsbergen. The samples from the present study were found 3000 km south of the previous site. The authors believe that even highly cautious scientists will now be convinced that flowering plants evolved long before the Cretaceous.

What might these primitive flowering plants have looked like? In the Middle Triassic, both the Barents Sea and Switzerland lay in the subtropics, but the area of Switzerland was much drier than the region of the Barents Sea. This implies that these plants occurred across a broad ecological range. The pollen’s structure suggests that the plants were pollinated by insects: most likely beetles, as bees would not evolve for another 100 million years.

EurekAlert! PR: http://www.eurekalert.org/pub_releases/2013-10/f-nfp092513.php

Study: http://journal.frontiersin.org/article/10.3389/fpls.2013.00344/full

A neurological basis for the lack of empathy in psychopaths

Selected coverage: Scientific American, WebMD

When individuals with psychopathy imagine others in pain, brain areas necessary for feeling empathy and concern for others fail to become active and be connected to other important regions involved in affective processing and decision-making, reports a study published in the open-access journal Frontiers in Human Neuroscience.

Psychopathy is a personality disorder characterized by a lack of empathy and remorse, shallow affect, glibness, manipulation and callousness. Previous research indicates that the rate of psychopathy in prisons is around 23%, greater than the average population which is around 1%.

To better understand the neurological basis of empathy dysfunction in psychopaths, neuroscientists used functional magnetic resonance imaging (fMRI) on the brains of 121 inmates of a medium-security prison in the USA.

Participants were shown visual scenarios illustrating physical pain, such as a finger caught between a door, or a toe caught under a heavy object. They were by turns invited to imagine that this accident happened to themselves, or somebody else. They were also shown control images that did not depict any painful situation, for example a hand on a doorknob.

Participants were assessed with the widely used PCL-R, a diagnostic tool to identify their degree of psychopathic tendencies. Based on this assessment, the participants were then divided in three groups of approximately 40 individuals each: highly, moderately, and weakly psychopathic.

When highly psychopathic participants imagined pain to themselves, they showed a typical neural response within the brain regions involved in empathy for pain, including the anterior insula, the anterior midcingulate cortex, somatosensory cortex, and the right amygdala. The increase in brain activity in these regions was unusually pronounced, suggesting that psychopathic people are sensitive to the thought of pain.

But when participants imagined pain to others, these regions failed to become active in high psychopaths. Moreover, psychopaths showed an increased response in the ventral striatum, an area known to be involved in pleasure, when imagining others in pain.

This atypical activation combined with a negative functional connectivity between the insula and the ventromedial prefrontal cortex may suggest that individuals with high scores on psychopathy actually enjoyed imagining pain inflicted on others and did not care for them. The ventromedial prefrontal cortex is a region that plays a critical role in empathetic decision-making, such as caring for the wellbeing of others.

Taken together, this atypical pattern of activation and effective connectivity associated with perspective taking manipulations may inform intervention programs in a domain where therapeutic pessimism is more the rule than the exception. Altered connectivity may constitute novel targets for intervention. Imagining oneself in pain or in distress may trigger a stronger affective reaction than imagining what another person would feel, and this could be used with some psychopaths in cognitive-behavior therapies as a kick-starting technique, write the authors.

EurekAlert! PR: http://www.eurekalert.org/pub_releases/2013-09/f-anb092313.php

Study: http://journal.frontiersin.org/article/10.3389/fnhum.2013.00489/full

Why do we enjoy listening to sad music?

Selected coverage: NY Times, BBC, Jerusalem Post, Popular Science, Huffington Post

Sad music might actually evoke positive emotions, reveals a new study by Japanese researchers published in the open-access journal Frontiers in Psychology. The findings help to explain why people enjoy listening to sad music, say Ai Kawakami and colleagues from Tokyo University of the Arts and the RIKEN Brain Science Institute, Japan.

Kawakami and colleagues asked 44 volunteers, including both musicians and non-specialists, to listen to two pieces of sad music and one piece of happy music. Each participant was required to use a set of keywords to rate both their perception of the music and their own emotional state.

The sad pieces of music included Glinka’s “La Séparation” in F minor and Blumenfeld’s Etude “Sur Mer” in G minor. The happy music piece was Granados’s Allegro de Concierto in G major. To control for the “happy” effect of major key, they also played the minor-key pieces in major key, and vice versa.

The researchers explained that sad music evoked contradictory emotions because the participants of the study tended to feel sad music to be more tragic, less romantic, and less blithe than they felt themselves while listening to it.

“In general, sad music induces sadness in listeners, and sadness is regarded as an unpleasant emotion. If sad music actually evokes only unpleasant emotion, we would not listen to it,” the researchers wrote in the study.

“Music that is perceived as sad actually induces romantic emotion as well as sad emotion. And people, regardless of their musical training, experience this ambivalent emotion to listen to the sad music,” added the researchers.

Also, unlike sadness in daily life, sadness experienced through art actually feels pleasant, possibly because the latter does not pose an actual threat to our safety. This could help people to deal with their negative emotions in daily life, concluded the authors.

“Emotion experienced by music has no direct danger or harm unlike the emotion experienced in everyday life. Therefore, we can even enjoy unpleasant emotion such as sadness. If we suffer from unpleasant emotion evoked through daily life, sad music might be helpful to alleviate negative emotion,” they added.

EurekAlert! PR: http://www.eurekalert.org/pub_releases/2013-07/f-wdw071113.php

Study: http://journal.frontiersin.org/article/10.3389/fpsyg.2013.00311/full

Caterpillars attracted to plant SOS

Plants that emit an airborne distress signal in response to herbivory may actually attract more enemies, according to a new study published in the open-access journal Frontiers in Plant Science.

A team of researchers from Switzerland found that the odor released by maize plants under attack by insects attract not only parasitic wasps, which prey on herbivorous insects, but also caterpillars of the Egyptian cotton leafworm moth Spodoptera littoralis, a species that feeds on maize leaves.

When damaged, many plants release hydrocarbons called volatile organic compounds, similar to the compounds that cause the characteristic smell of freshly cut grass. These volatile organic compounds are known to be attractive to parasitoid wasps that lay their eggs inside other insects, killing them. Plants appear to use this strategy to fight back against herbivorous insects by calling for their enemies’ enemies. In contrast, herbivorous insects tend to avoid the herbivore-induced volatile organic compounds.

“Adult moths and butterflies avoid food plants that are under attack by conspecifics. This seems adaptive, because it reduces both competition and the risk of predation by parasitoids. But we found that S. littoralis caterpillars are actually attracted to the odor of damaged maize plants, even when this odor is mimicked in the laboratory with a mix of synthetic compounds,” said Prof. Ted Turlings, an author of the study and head of the Laboratory for Fundamental and Applied Research in Chemical Ecology Institute of Biology at the University of Neuchâtel, Switzerland.

To determine what kind of odors the caterpillars preferred, the researchers let the caterpillars chose among several odors by placing them in an olfactometer, a device consisting of four tubes connected to a central chamber, with each tube introducing an airflow carrying a different odor. The caterpillars were more than twice as likely to crawl towards the odor from maize plants under attack by conspecifics than towards undamaged plants, especially if the damage was recent and the caterpillars had already fed on maize.

So what might be the advantage to the caterpillars of moving towards plants that are already infested? “When S. littoralis caterpillars drop from a plant they are highly vulnerable to predators and pathogens in the soil, as well as to starvation. The advantage seems to be that fallen caterpillars can quickly rediscover the plant on which they fed. The caterpillars feed less and move more when exposed to high concentrations of the volatiles. By moving away from freshly damaged sites, they can minimize risk of predation and avoid competition,” explained Prof. Turlings.

Turlings and colleagues propose that hungry S. littoralis caterpillars do the best of a bad job by moving towards volatile organic compounds released by damaged maize plants. On these plants the competition may be more intense, but at least the caterpillars are assured of a suitable plant. Adult moths, on the other hand, are much more mobile and take little risk exploring the environment to discover the best food source — so they avoid maize that is already under attack.

EurekAlert! PR: http://www.eurekalert.org/pub_releases/2013-07/f-cat070113.php

Study: http://journal.frontiersin.org/article/10.3389/fpls.2013.00209/full

How similar are the gestures of apes and human infants? More than you might suspect

Selected coverage: Smithsonian Magazine, Der Spiegel, LA Times, Slate, NBC, Discovery News, Yahoo, The Telegraph, Daily Mail

With Gozde Zorlu (Frontiers); Stuart Wolpert, Kristen Gillespie & Patricia Greenfield (UCLA Media Relations) 

Psychologists who analyzed video of a female chimpanzee, a female bonobo and a female human infant in a study to compare different types of gestures at comparable stages of communicative development found remarkable similarities among the three species.

This is the first time such data have been used to compare the development of gestures across species. The chimpanzee and bonobo, formerly called the “pygmy chimpanzee,” are the two species most closely related to humans in the evolutionary tree.

“The similarity in the form and function of the gestures in a human infant, a baby chimpanzee and a baby bonobo was remarkable,” said Patricia Greenfield, a distinguished professor of psychology at UCLA and co-author of the study.

Gestures made by all three species included reaching, pointing with fingers or the head, and raising the arms to ask to be picked up. The researchers called “striking” the finding that the gestures of all three species were “predominantly communicative,” Greenfield said.

To be classified as communicative, a gesture had to include eye contact with the conversational partner, be accompanied by vocalization (non-speech sounds) or include a visible behavioral effort to elicit a response. The same standard was used for all three species. For all three, gestures were usually accompanied by one or more behavioral signs of an intention to communicate.

Charles Darwin showed in his 1872 book “The Expression of the Emotions in Man and Animals” that the same facial expressions and basic gestures occur in human populations worldwide, implying that these traits are innate. Greenfield and her colleagues have taken Darwin’s conclusions a step further, providing new evidence that the origins of language can be found in gestures and new insights into the co-evolution of gestures and speech.

The findings are published today in the open-access journal Frontiers in Psychology.

The apes included in the study were named Panpanzee, a female chimpanzee (Pan troglodytes), and Panbanisha, a female bonobo (Pan paniscus). They were raised together at the Language Research Center in Atlanta, which is co-directed by Sue Savage-Rumbaugh, a co-author of the study. There, the apes learned to communicate with caregivers using gestures, vocalizations and visual symbols (mainly geometric shapes) called lexigrams.

“Lexigrams were learned, as human language is, during meaningful social interactions, not from behavioral training,” said the study’s lead author, Kristen Gillespie-Lynch, an assistant professor of psychology at the City University of New York and a former UCLA graduate student in Greenfield’s laboratory.

The human girl grew up in her parents’ home, along with her older brother. Where the apes’ symbols were visual, the girl’s symbols took the form of spoken words. Video analysis for her began at 11 months of age and continued until she was 18 months old; video analysis for the two apes began at 12 months of age and continued until they were 26 months old. An hour of video was analyzed each month for the girl, the chimpanzee and the bonobo.

Overall, the findings support the “gestures first” theory of the evolution of language. During the first half of the study, communicating with gestures was dominant in all three species. During the second half, all three species increased their symbol production — words for the child and lexigrams for the apes.

“Gesture appeared to help all three species develop symbolic skills when they were raised in environments rich in language and communication,” said Gillespie-Lynch, who conducted the research while she was at UCLA. This pattern, she said, suggests that gesture plays a role in the evolution, as well as the development, of language.

At the beginning stage of communication development, gesture was the primary mode of communication for human infant, baby chimpanzee and baby bonobo. The child progressed much more rapidly in the development of symbols. Words began to dominate her communication in the second half of the study, while the two apes continued to rely predominantly on gesture.

“This was the first indication of a distinctive human pathway to language,” Greenfield said.

All three species increased their use of symbols, as opposed to gestures, as they grew older, but this change was far more pronounced for the human child. The child’s transition from gesture to symbol could be a developmental model of the evolutionary pathway to human language and thus evidence for the “gestural origins of human language,” Greenfield said.

While gesture may be the first step in language evolution, the psychologists also found evidence that the evolutionary pathway from gesture to human language included the “co-evolution of gestural and vocal communication.” Most of the child’s gestures were accompanied by vocalization (non-language sounds); the apes’ gestures rarely were.

“This finding suggests that the ability to combine gesture and vocalization may have been important for the evolution of language,” Greenfield said.

The researchers conclude that humans inherited a language of gestures and a latent capacity for learning symbolic language from the last ancestor we share with our chimpanzee and bonobo relatives — an ancestor that lived approximately 6 million years ago.

The evolution of human language built on capacities that were already present in the common ancestor of the three species, the psychologists report.

“Our cross-species comparison provides insights into the communicative potential of our common ancestor,” Gillespie-Lynch said.

The article is titled “A cross-species study of gesture and its role in symbolic development: implications for the gestural theory of language evolution.” Other co-authors were Yunping Feng and Heidi Lyn.

EurekAlert! PR: http://www.eurekalert.org/pub_releases/2013-06/uoc–hsa060313.php

Study: http://journal.frontiersin.org/article/10.3389/fpsyg.2013.00160/full