New study reveals impact of chatGPT on public knowledge sharing

ChatGPT led to a 25% drop in activity on Stack Overflow. There are major implications for AI's future, according to the study's authors

Complexity Science Hub

 

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An extended timeseries of the weekly posts to Stack Overflow. The figure highlights the release of ChatGPT and the conclusion of the data used in the statistical analyses, respectively. After May 2023, the decline in posting activity continues, albeit at a slower rate.

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Credit: Maria del Rio-Chanona, Nadzeya Laurentsyeva, Johannes Wachs

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Vienna, September 25 2024]— A new study published in PNAS Nexus reveals that the widespread adoption of large language models (LLMs), such as ChatGPT, has led to a significant decline in public knowledge sharing on platforms like Stack Overflow. The study highlights a 25% reduction in user activity on the popular programming Q&A site within six months of ChatGPT's release, relative to similar platforms where access to ChatGPT is restricted.

“LLMs are so powerful, have such a high value, and make a huge impact on the world. One begins to wonder about their future,” says first author Maria del Rio-Chanona, an associate faculty member at the Complexity Science Hub (CSH).

“Our study hypothesized that instead of posting questions and receiving answers on public platforms like Stack Overflow, where everybody can see them and learn from them, people are asking privately on ChatGPT instead. However, LLMs like ChatGPT are also trained on this open and public data, which they are replacing in some way. So what's going to happen?,” adds Del Rio-Chanona, who’s also an assistant professor at University College London, an associate researcher at the Institute for New Economic Thinking at the Oxford Martin School, and the Bennett Institute for Public Policy, University of Cambridge.

Implications are Major

“In our findings, we noticed less and less questions and answers on Stack Overflow after ChatGPT was released. This has quite big implications. This means there may not be enough public data to train models in the future” warns Del Rio-Chanona. In this study, she worked together with Nadzeya Laurentsyeva, from Ludwig Maximilian University of Munich; and Johannes Wachs, faculty member at CSH and professor at Corvinus University in Budapest. 

“Stack Overflow is an immensely valuable knowledge database accessible to anyone with an internet connection. People all over the world learn from questions and answers that other people post,” says Wachs. In fact, even AI models like ChatGPT are trained on human generated content like Stack Overflow posts. Ironically, the displacement of human content creation by AI will make it more difficult to train future AI models. Using data generated by AI to train new models is generally thought to perform poorly, a process likened to making a photocopy of a photocopy.

A Shift from Public to Private

The findings also point out scenarios that go beyond mere technological changes to touch the fabric of our economic and social structures as well. Users may become less inclined to contribute to open knowledge platforms as they interact more with LLMs like ChatGPT, resulting in valuable data being transferred from public repositories to privately-owned AI systems, explain Del Rio-Chanona and colleagues.

“This represents a significant shift of knowledge from public to private domains,” argue the researchers. According to them, this could also deepen the competitive advantage of early movers in AI, further concentrating knowledge and economic power.

All experience and quality levels

Del Rio-Chanona and her colleagues found that the decline in content creation on Stack Overflow affected users of all experience levels, from novices to experts. They also observed that the quality of posts did not decrease significantly, as measured by user feedback, indicating that both low and high quality contributions are being displaced by LLMs.

In addition, the study showed that posting activity in some programming languages, such as Python and Javascript, dropped significantly more than the platform’s average. “The results suggest that people are indeed asking questions about Python and Javascript, two of the most commonly used programming languages, on ChatGPT rather than Stack Overflow,” says Del Rio-Chanona. 

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About the Study

This research, titled "Large Language Models Reduce Public Knowledge Sharing on Online Q&A Platforms," by R Maria del Rio-Chanona, Nadzeya Laurentsyeva, and Johannes Wachs, was published in PNAS Nexus and is available online.

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About CSH

The Complexity Science Hub (CSH) is Europe’s research center for the study of complex systems. We derive meaning from data from a range of disciplines —  economics, medicine, ecology, and the social sciences — as a basis for actionable solutions for a better world. Established in 2015, we have grown to over 70 researchers, driven by the increasing demand to gain a genuine understanding of the networks that underlie society, from healthcare to supply chains. Through our complexity science approaches linking physics, mathematics, and computational modeling with data and network science, we develop the capacity to address today’s and tomorrow’s challenges.

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Journal

PNAS Nexus

DOI

10.1093/pnasnexus/pgae400 

Method of Research

Data/statistical analysis

Subject of Research

People

Article Title

Large language models reduce public knowledge sharing on online Q&A platforms

 

Severity of road accidents and the injuries sustained vary according to sex of the driver and passengers

A study by the University of Granada has analysed the characteristics of the drivers and passengers of the 171,230 cars involved in traffic accidents in Spain between 2014 and 2020.

University of Granada

 

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Car Accident

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Credit: University Of Granada

The severity of traffic accidents and of the injuries sustained in them is influenced by whether the individuals involved are male or female. This issue has been studied previously by other researchers, but the results are not consistent across studies. In general, most authors have reported that the risk of death or serious injury in traffic accidents is higher for men than for women. However, some researchers have found that in similar accidents women are more likely to be seriously injured or hospitalised. A new UGR study shows that the risk of death or serious injury among passengers is statistically lower when the driver is female. The analysis also reveals that the risk of death or major injury is higher for female occupants.

The results of the study have been published in the 30 July issue of the open-access journal Heliyon. The research was carried out by Pablo Lardelli-Claret, Eladio Jiménez-Mejías, Mario Rivera Izquierdo and Virginia Martínez Ruiz, all members of the University of Granada’s Department of Preventive Medicine and Public Health, as well as Nicolás Francisco Fernández-Martínez and Luis Miguel Martín de los Reyes, from the Andalusian School of Public Health (EASP).

The aim of the study was to try to clarify the relationship between the sex of the driver and passengers in vehicles involved in road traffic accidents and the severity of the injuries sustained. To do so, the researchers studied the characteristics of the occupants (drivers and passengers) of the 171,230 passenger cars involved in traffic accidents in Spain between 2014 and 2020, as recorded in the National Register for Road Traffic Accident Victims, provided by the Spanish Directorate-General for Traffic (DGT).

Based on the data, the researchers designed two studies. In the first, they assessed the relationship between the sex of the driver and the occurrence of death or serious injury among the passengers. The second examined the relationship between the sex of the occupants in the vehicle and their risk of death or serious injury as a result of the accident.

The first study concluded that the risk of death or serious injury among passengers is 28% lower when the driver is female than when the driver is male. The results suggest that this lower risk could largely be explained by safer driving by women. However, it could also partly be due to women preferring to drive in environments where the severity of an accident, should it occur, is lower (for example in urban areas compared to larger roads). These results would therefore support the view, already put forward by other authors, that it would be desirable to attempt to «feminise» driving; in other words, for men to adopt driving styles that have until now been more typical among women.

However, the data analysis from the second study, which compared all the occupants of the vehicle involved in a crash, showed that the risk of death or serious injury was 20% higher for female occupants. As the study took into account the position of the passengers and whether or not they were wearing a seatbelt at the time of the accident, this result could be attributed to biological and body size differences, which would make women more vulnerable to the effects of the energy released in an accident.

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Journal

Heliyon

DOI

10.1016/j.heliyon.2024.e34472 

Method of Research

Observational study

Subject of Research

People

Article Title

Which is the role of driver- or passengers-sex on the severity of road crashes?

MATRIARCY

Twice as many women as men were buried in the megalithic necropolis of Panoria according to a multidisciplinary study

Multidisciplinary study uncovers gender bias at the megalithic necropolis of Panoria where twice as many women were buried

University of Granada

 

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Megalithic necropolis of Panoria (Spain)

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Credit: University Of Granada

A multidisciplinary research team led by the Archaeometry research group of the University of Tübingen and the GEA research group of the University of Granada made a surprising discovery in the megalithic necropolis of Panoría (Granada, Spain): twice as many women as men were buried, a bias that is even more pronounced among the juvenile population, where the ratio is 10 females for every male.

The necropolis of Panoría is located at the easternmost end of Sierra Harana, in the town of Darro (Granada). It consists of at least 19 graves, 9 of which have been excavated between 2015 and 2019. They are collective burials from which more than 55,000 human skeletal remains were recovered. The dating of these remains shows that the first burials took place 5600 years ago with a discontinuous funerary use until 4100 years ago.

In a recent study published in the prestigious journal Scientific Reports, the use of new bioarchaeological methods has allowed the identification of chromosomal sex from the study of DNA and the analysis of a protein known as Amelogenin present in the tooth enamel. In this way, it has been possible, for the first time, to obtain a precise demographic profile of the biological sex of the people who were buried in these megalithic monuments. Surprisingly, the result is a clear bias in favour of female burials, twice that of male burials, a bias that is even more pronounced among juvenile individuals with a ratio of 10 females for every male individual. This ratio is far from the usual composition of human populations, which is approximately one to one. Only in exceptional circumstances, e.g. conflicts, wars or intense migration processes, does this ratio break down in favour of one of the sexes.

What circumstances could have led to such a pronounced bias in the population buried at Panoría? The bias in favour of female burials appears in all the analysed graves, in all age groups and throughout the time of use of the necropolis. This allows us to confirm that this was a very persistent and determining social decision over time affecting the different social groups buried within the graves. Therefore, extraordinary or unpredictable events can been ruled out as the cause of the bias found in Panoría.

If sex bias was a social decision, but what are the reasons for this over-representation of women in funerary rituals? Considering that biological kinship relations are the main criterion to be buried in the different structures, the over-representation of female individuals could indicate funerary practices based primarily on matrilineal descent. This means that family relationships and social belonging are established through the maternal line. This would explain the bias in favour of women and the absence of young male individuals who could have joined other kin groups, a common practice known in anthropology as male exogamy. In any case, the over-representation of women would indicate a female-centred social structure, in which gender would have influenced funerary rituals and cultural traditions.

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Journal

Scientific Reports

DOI

10.1038/s41598-024-72148-x 

Method of Research

Observational study

Subject of Research

People

Article Title

) Female sex bias in Iberian megalithic societies through bioarchaeology, aDNA and proteomics

Article Publication Date

23-Sep-2024

 

Political sanctions: the tougher, the better?

Could implementing stronger sanctions targeting, for example, Russia, have prevented military aggression? Political scientists at the University of Konstanz publish a study on sanctions' potential.

University of Konstanz

Before beginning its war of aggression against Ukraine in 2022, Russia had already conducted an aerial bombardment of Georgia in 2008 and invaded Crimea as well as the Donbas region in 2014. This has left politicians and researchers puzzling over the question: Would it have been possible to prevent the current war in Ukraine if countries had implemented more decisive and intensive sanction policies back then?

In a new study, Gerald Schneider, a professor of international politics at the University of Konstanz, and Thies Niemeier, a doctoral researcher at the Konstanz Graduate School of the Social and Behavioural Sciences (GSBS), project how effective tougher sanctions could have been. Their assessment is based on a statistical model that compares the political and economic relationships between countries to the success of sanctions. This allows them to identify the factors that are likely to make sanctions more successful. These variables include a higher intensity of sanctions, closer economic ties to the sanctioned country and the country's history of having been a colony of a European country.

Taking lessons from the past
"It is extremely important for politicians to be able to fully assess the likely consequences of various political measures. Ideally, they should be able to evaluate these effects ahead of time and decide accordingly", says lead author Thies Niemeier. However, even afterwards it is useful to draw conclusions about the connection between the strength of sanctions and their impact. The researchers use "counterfactual scenarios" to analyze what would have happened differently if certain political measures had been taken earlier, had been more robust or had been implemented differently.

Thies Niemeier and Gerald Schneider studied sanctions levied against Egypt, Burundi, Mali and Russia by the European Union and the United States. They classify sanctions into different degrees of intensity. According to their model, examples of "light measures" include restrictions on the freedom of movement of specific Russian oligarchs implemented after 2014, as well as barriers to investment by individual Russian companies. Further categories of sanctions involve steps like banning the arms trade and freezing development aid or limiting trade in certain industrial sectors. The toughest category includes wide-ranging economic embargoes, like those once introduced against South Africa and currently imposed on Russia.

The greater the intensity, the greater the effectiveness
The researchers found that – at least with regard to the EU – robust measures in response to Russia's annexation of Crimea and the invasion of the Donbas region would have had a greater impact than the moderate approach that had been used. "When they are more credible and costly for the target country, economic sanctions are more likely to induce the country to make concessions", says Gerald Schneider. Especially in Africa, it has proven successful on several occasions for the EU or USA along with the African Union or the Economic Community of West African States (ECOWAS) to mount a quick, robust response.

What about Russia? "Our models suggest that intensive sanctions in 2014 would have had a high probability of increasing the cost of future aggression and making President Putin more willing to negotiate", Gerald Schneider explains, "even if they would probably not have been enough to move Russia to withdraw from Crimea". The political scientists base this projection on the close economic and political ties between the EU and Russia as well as the resulting negotiating power of Brussels.

Gerald Schneider concludes: “The 2014 sanctions that were watered down as the result of lobbying from the financial and energy industries reinforced President Putin's mistaken belief that increasing the level of aggression against Ukraine would result in only a few costly sanctions.” According to the study, while tougher EU sanctions would have made Russia more willing to make concessions, similar measures by the USA would have had little success. The model predicts that stronger sanctions by the Western superpower do not necessarily have a greater impact.

US-American strategies in sanctioning
According to the study, the intensity of economic ties to the sanctioned country generally influences how effective sanctions will turn out to be. Being the Western superpower the United States can follow a different strategy when sanctioning countries. "When a world power like the United States threatens sanctions, the countries facing the prospect of these sanctions tend to back down so that the sanctions do not actually have to be imposed on them", Thies Niemeier explains. "Another factor is that the US sometimes enacts strong economic sanctions against countries that depend little on the US economy. These sanctions cannot be successful if they do not cause economic pressure".

The original study is available online at: https://doi.org/10.1177/20531680241272668

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DOI

10.1177/20531680241272668 

 

Study reveals mallards' flight responses ineffective in preventing vehicle collisions

n

PeerJ

 

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Inefficacy of mallard flight responses to approaching vehicles.

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Credit: https://doi.org/10.7717/peerj.18124

Research Highlights Risk to Both Humans and Wildlife, Suggests Need for New Collision Mitigation Strategies

A recent article published in PeerJ Life & Environment has uncovered insights into how mallards (Anas platyrhynchos) respond to approaching vehicles, revealing that these common waterbirds are poorly equipped to avoid collisions, particularly at high speeds. The research, which used both simulated and real-world vehicle approaches, highlights the urgent need for improved methods to reduce bird-vehicle collisions—events that are not only financially costly but also dangerous to both humans and wildlife.

 The study focused on the behavior of mallards when exposed to vehicles approaching at different speeds and under varying light conditions (day vs. night). Results showed that mallards demonstrated a reduced likelihood of attempting escape when faced with simulated nighttime vehicle approaches. However, when they did attempt to flee, they did so with more time to spare compared to daytime scenarios.

“Our findings suggest that the looming headlights of vehicles at night may not be perceived as a significant threat by mallards. The lights visible at night are a more abstract stimulus than a predator or the body of a vehicle visible during the day, and may not provoke the same level of threat response needed to adequately respond. Mallard visual systems may also not  be well adapted to low-light settings or attuned to standard vehicle lighting," said Guenin, the lead researcher. 

Mallards' responses were further tested using real vehicles, where they exhibited an additional concerning behavior—a delayed margin of safety. Both the distance at which birds initiated flight and the time available to avoid a collision decreased as vehicle speed increased. This marks mallards as the first bird species known to exhibit this response to vehicles, making high-speed encounters especially dangerous.

Key Findings:

• Mallards exposed to nighttime vehicle approaches were less likely to attempt escape
• Mallards displayed a delayed margin of safety, increasing the risk of collisions at high speeds.
• The study suggests mallards are wholly unequipped to respond to vehicles at high speeds, with successful escapes occurring in less than 20% of approaches at the takeoff speed of aircraft (240 km/h).

The delayed margin of safety observed in mallards poses particular concern for airports and roads near water bodies where these birds frequently congregate. Despite efforts to reduce wildlife presence in these areas, complete separation is often impractical due to the birds’ adaptability to human environments.

"With mallards being active at night, particularly during migration, the risk of collisions is heightened, especially for aircraft. Most mallard strikes occur below 1,000 meters, suggesting that low-altitude flights during migration months pose the greatest danger.," 

Recommendations:

• Aircraft and vehicle operations should be minimized as much as practical during night hours and peak migration periods to reduce the risk of bird strikes.
• Future research should focus on enhancing the visual saliency of vehicles to birds, particularly at night, to allow for earlier detection and avoidance.

The research underscores the need for ongoing studies into avian avoidance behaviors and encourages the development of innovative solutions to improve safety for both humans and wildlife.

 

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Journal

PeerJ

DOI

10.7717/peerj.18124 

Article Title

Inefficacy of mallard flight responses to approaching vehicles

Article Publication Date

25-Sep-2024

 

Managing stress could be the key to helping highly impulsive people act rashly when bored

Sometimes we all just need to mentally switch off and do nothing, but some people find the experience more stressful than relaxing according to new research from the University of Portsmouth in England.

University of Portsmouth

Research at the University of Portsmouth has explored the relationship between high impulsivity and boredom, in an effort to find out what drives rash and sometimes unhealthy decisions.

Impulsivity is the tendency to act quickly, and without thinking things through. It is linked to several psychiatric disorders, including ADHD, Borderline Personality Disorder, and Substance Use Disorders.

While it is well-known there is a strong link between boredom and impulsiveness, two new studies have shed light on the role stress plays in this relationship. 

The results, published in Physiology & Behavior, found participants with high trait impulsivity reported greater levels of boredom following a dull task. While this finding was expected, the new discovery was that these individuals experienced a greater physiological reaction by releasing more of the stress hormone cortisol.

Dr James Clay, lead author and researcher at the Canadian Institute for Substance Use Research and Dalhousie University said: "Our findings shed light on the biological underpinnings of why some individuals, particularly those with high impulsivity, find boredom more stressful than others. By identifying how their stress response is triggered, and that cortisol is a key mediator, we can begin to better understand why this happens and to explore targeted interventions that help manage these reactions. 

“This opens up new avenues for developing personalised approaches to reduce stress and improve mental health, especially for those who struggle with impulse control and the negative consequences of boredom.”

Boredom is a form of psychological stress for most people, because it is a state of restless dissatisfaction and often leads an individual to seek out stimulation.  However, more impulsive people’s inherent response to stressful events could be the reason why they are more triggered by boring situations.

Senior author, Dr Matt Parker is a neuroscientist specialising in the study of stress, who now works at the University of Surrey. He said: “We know highly impulsive people are more likely to develop addictions over a lifespan. There has always been a connection between impulsiveness and boredom, but the mechanisms behind this relationship aren’t fully understood.

“For instance, early theories suggested people with ADHD struggle with boredom because they don’t like to wait, and because of this they tend to act rashly. But what makes them impatient, and how can we mitigate this feeling so that they are more comfortable with being bored?

“That’s where stress comes in. Our research supports the hypothesis that high-impulsive people experience greater physiological responses to boredom. If we can find ways to mitigate these stress symptoms it might prevent them from seeking unhealthy stress reliefs, like drugs or gambling.”

In the first study, 80 participants completed a boring task and reported on how it made them feel. The results supported existing evidence that impulsive individuals are more prone to boredom than others.

The second monitored 20 people’s physiological response to boredom, by testing samples of their saliva for cortisol, both pre and post-task. It found the system that manages the body's stress response - known as the hypothalamic-pituitary-adrenal (HPA) axis - increased the levels of the stress hormone in the body during the task.

“Knowing that the stress response links boredom with impulsivity brings us a step closer to developing potential solutions to break the cycle”, explained co-author Juan Badariotti from the University of Portsmouth’s School of Psychology, Sport and Health Sciences. 

“We hope this discovery will inspire future research into potential interventions at breaking this feedback loop of boredom, stress, and impulsiveness, and eventually develop more effective coping mechanisms for psychiatric disorders.”

The paper’s authors recommend future research should replicate the second study with a larger sample of participants, and measure how prone they are to boredom as well as impulsiveness.

ENDS

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Journal

Physiology & Behavior

DOI

10.1016/j.physbeh.2024.114637 

Method of Research

Experimental study

Subject of Research

People

Article Title

HPA activity mediates the link between trait impulsivity and boredom

Article Publication Date

1-Oct-2024

 

Small accounts, big decisions: How multiple savings impact retirement payout choices

The Hebrew University of Jerusalem

New study shows that retirees are more likely to cash out smaller retirement accounts instead of turning them into steady income streams, even though they might do the opposite with larger accounts. This choice can hurt their long-term financial security, leaving them with less stable income in retirement. For financial companies, this behavior has implications in their ability to manage assets liabilities risks (ALM).

A new study by Dr. Abigail Hurwitz and Prof. Orly Sade from Hebrew University, forthcoming in Management Science, sheds light on how retirees manage their savings across multiple accounts and its impact on their payout decisions at retirement. Titled Is One Plus One Always Two? Insuring Longevity Risk While Having Multiple Savings Accounts, the research explores how individuals with more than one retirement savings account choose between annuitization—insuring themselves against longevity risk—and cashing out their savings in a lump sum.

Drawing on proprietary data from a leading Israeli insurance company, accompanied by a laboratory experiment and an online experimental survey, the study highlights a critical trend: smaller accounts are much more likely to be cashed out than larger ones. The researchers use occupation as a proxy for wealth and find that individuals with higher expected wages are more likely to annuitize their savings but less likely to annuitize smaller accounts. This behavior, according to Hurwitz and Sade, is not merely about income but also the diversification of savings across multiple accounts.

“We discovered that the composition of multiple accounts influences annuitization decisions, especially for smaller versus larger accounts,” said Dr. Abigail Hurwitz. “This can have significant implications for retirees, particularly regarding their long-term financial security.”

The study uses both administrative data and a series of experiments to analyze this phenomenon. An online survey and a laboratory experiment revealed that retirees are less likely to annuitize small accounts due to mental accounting, a concept that leads individuals to treat money differently depending on how it is categorized or allocated. A supplementary survey conducted with financial experts indicated that these professionals were less influenced by the distribution of funds across accounts and were more inclined to consider the entire portfolio.

The study's findings are far-reaching, particularly for financial institutions managing pension funds. “Our results suggest that financial institutions should consider the size distribution of accounts when forecasting annuitization behavior and longevity risk,” said co-author Prof. Orly Sade. “It is vital for asset and liability management strategies, especially as these decisions directly impact the future reserves required for annuity providers.”

This research provides crucial insights into how retirees manage their savings and make annuitization decisions, highlighting significant implications for both financial institutions and policymakers.

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Journal

Management Science

DOI

10.1287/mnsc.2022.02489 

Method of Research

Data/statistical analysis

Subject of Research

People

Article Title

Is One Plus One Always Two? Insuring Longevity Risk While Having Multiple Savings Accounts

 

Gender equity paradox: sex differences in reading and science as academic strengths are largest in gender-equal countries

University of Turku

A new study reveals that sex differences in academic strengths are found throughout the world and girls’ relative advantage in reading and boys’ in science is largest in gender-equal countries. 

Gender equality often draws attention especially in fields where women are underrepresented, such as high-status, high-paying STEM (Science, Technology, Engineering, and Mathematics) careers. Academic strengths, or a student’s best subject, strongly influence their field of study. Students with strengths in mathematics or science gravitate toward STEM fields, while those with a strength in reading gravitate toward other fields (e.g., journalism). 

The research team analysed data from nearly 2.5 million adolescents in 85 countries over 12 years or in five waves (2006-2018) from the Programme for International Student Assessment (PISA). Their findings confirmed that girls’ strength is typically reading, while boys’ is typically mathematics or science. These patterns are found both across countries and time. 

Most notably, sex differences in reading and science as academic strengths are more pronounced in countries with greater gender equality, such as Finland. Sex differences in mathematics, on the other hand, remained stable regardless of country-level gender equality.

"These results suggest that in more gender-equal societies, women may be choosing fields other than STEM based on their strength in reading. Increasing the share of women in STEM will require more than just boosting girls' math and science skills or advancing gender equality," says Doctoral Researcher Marco Balducci from the INVEST Research Flagship at the University of Turku, Finland.

The finding that sex differences in academic strength in reading and science are larger in gender-equal Scandinavian countries than in more traditional Middle Eastern countries –known as the Gender Equality Paradox – challenges the popular belief that sex differences are mainly driven by socialisation pressure. 

"The common assumption is that as gender equality improves, traditional gender roles should fade, leading to smaller sex differences. But that is not what we found. Instead, our results align with recent research showing that sex differences either stay the same or even increase with more gender equality," says Balducci.

Professor David Geary from the University of Missouri notes that “Gender-equal, wealthy, and liberal countries offer more opportunities and allow greater freedom of choice. In these contexts, men and women make different decisions, leading to larger sex differences in various areas of life, including STEM fields.”

The research team encourages policymakers to prioritise mentorship opportunities for talented girls, as these may increase their likelihood of enrolling in a STEM degree programme. However,  Balducci adds that “our study highlights that achieving parity between boys and girls could be challenging as broader factors, like sex differences in academic strengths, play a key role in determining sex disparities in STEM."

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Journal

Psychological Science

DOI

10.1177/09567976241271330 

Article Title

The Gender-Equality Paradox in Intraindividual Academic Strengths: A Cross-Temporal Analysis

 

Reconstructing the evolutionary history of the grape family

A new ancestor of the grape family

University of Barcelona

 

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Nekemias mucronata fossil lateral leaflets from the collection of the Natural Science Museum of Barcelona.

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Credit: Natural Science Museum of Barcelona

Until now, it was believed that plants of the grape family arrived at the European continent less than 23 million years ago. A study on fossil plants draws a new scenario on the dispersal of the ancestors of grape plants and reveals that these species were already on the territory of Europe some 41 million years ago. The paper describes a new fossil species of the same family, Nekemias mucronata, which allows us to better understand the evolutionary history of this plant group, which inhabited Europe between 40 and 23 million years ago.

This study, published in the Journal of Systematics and Evolution (JSE), is led by researcher Aixa Tosal, from the Faculty of Earth Sciences and the Biodiversity Research Institute (IRBio) of the University of Barcelona. The article is also signed by Alba Vicente, from the Biodiversity Research Institute (IRBio) and the Catalan Institute of Palaeontology Miquel Crusafont (ICP), and Thomas Denk, from the Swedish Museum of Natural History (Stockholm).

A new ancestor of the grape family

The grape family (Vitaceae) is made up of some 950 species, and is divided into five tribes (in botany, this is an intermediate taxonomic classification between the family and the genus). One of these tribes is the Viteae, made up of 200 species, including the grape vine plant (Vitis vinifera), which is of great global economic interest. The new paper published in the JSE focuses on studying the tribe Ampelopsideae, made up of 47 species.

“Our study changes the paradigms accepted until now and shows that the Ampelopsis and Nekemias lineages of the Ampelopsideae tribe were already present in Europe and Central Asia during the middle Eocene (between 47 and 37 million years ago). This indicates that this dispersal was approximately 20 million years earlier than previously estimated”, says Aixa Tosal, first author of the study and member of the UB’s Department of Earth and Ocean Dynamics.

“In particular, we show that a lineage now restricted to North America already existed in Europe and Central Asia, thanks to the discovery of the fossil species Nekemias mucronata, which is very similar to the present-day North American Nekemias arborea. Nekemias mucronata cohabited with Ampelopsis hibschii, the closest relative of today’s Ampelopsis orientalis”, explains Tosal. In contrast, the latter has had a different dispersal from N. mucronata, as this lineage is now endemic to the eastern Mediterranean. “This study helps us to better understand the evolution of the Ampelopsideae tribe during the second dispersal pulse, especially in Europe and Central Asia, which took place during the Palaeogene”, says Tosal.

Nekemias mucronata lived from the late Eocene to the late Oligocene (37-23 million years ago). It seems that it was able to grow in a broad range of climates, from regions with low winter temperatures (-4.6 °C in cold periods) — such as those found in Kazakhstan during the Oligocene (33-23) million years ago — to regions with warm mean annual temperatures — such as those of the Oligocene in the Iberian Peninsula — or even in climates with intermediate temperatures such as those recorded in the centre of the European continent.

“N. mucronata was also not overly demanding in terms of rainfall. It could grow in areas with abundant rainfall and low rainfall seasonality; for example, in Central Europe during the Oligocene, or the Iberian Peninsula or Greece during the same time”, says ICP researcher Alba Vicente. “This fossil species had a compound leaf, a peculiarity shared with some species of the vine family. Although it is difficult to confirm the number of leaflets of the compound leaf, it would have consisted of at least three. We have been able to recognize common patterns between the apical and lateral leaflets, which allows us to distinguish them from other fossil species of the vine family in Eurasia”, he adds. “What makes Nekemias mucronata unique is the presence of a mucro at the tip of the leaflet teeth, which gives the species its name. The straight shape of the base of the apical leaflet is also quite distinctive, as all other Eurasian fossil species are buckled (with an invagination near the petiole)”, says Vicente.

Dispersal of Ampelopsideae across the Atlantic bridge or the Bering Strait

To date, the oldest record of the grape family has been found in the Upper Cretaceous deposits of India (75-65 Ma). The earliest record of the plant lineage in the Americas is from the Upper Eocene, around 39.4 million years ago, and at about the same time in Europe and Central Asia the Ampelopsis and Nekemias lineages are already found.

How did these species disperse in the past? These tribes diverged between the Upper Cretaceous and the Upper Eocene and, although there are still many unknowns, it seems that they dispersed and evolved quite rapidly. According to current data, which are consistent with the molecular clock technique, “the Ampelopsideae could have followed two cluster routes or a mixture of both. The first proposed route follows the North Atlantic isthmus. That is, the family appeared in India, then moved on to central Asia and Europe during the middle Eocene (between 47 and 37 million years ago), and finally moved on to the Americas via Greenland”, says Thomas Denk. “Another possible route suggests that, once the Vitaceae family appeared in India, the Ampelopsideae tribe dispersed eastward from Asia during the middle Eocene (47-37 million years ago) and quickly moved to the Americas via the Bering Strait, and from there to Europe along the North Atlantic isthmus”, Denk says.

Although the dispersal of these two species does not seem to be linked to climate, it is possible that the increase in aridity during the Oligocene in the Iberian Peninsula and southern Europe explains the extinction (27-23 million years ago) of the last population of N. mucronata found in the Iberian Peninsula. In parallel, Ampelopsis hibschii was restricted to the Balkan area and finally became extinct about 15 million years ago.

“However, there are still many unanswered questions about the early dispersal phases (from the Late Cretaceous to the Palaeogene). For this reason, we would like to continue studying this family, and perhaps we will be able to unravel what happened during their early cluster phases, which occurred between 66 and 41 million years ago”, the team concludes.

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Journal

Journal of Systematics and Evolution

DOI

10.1111/jse.13126. 

Method of Research

Observational study

Subject of Research

Not applicable

Article Title

https://onlinelibrary.wiley.com/doi/10.1111/jse.13126