Microplastics and triphenyltin amplify toxicity via the gut-brain axis

Peer-Reviewed Publication

EURASIA ACADEMIC PUBLISHING GROUP 

NEWS RELEASE 8-JUN-2023

Regulating environmental pollution around the world still largely relies upon risk assessments of “single pollutants,” ignoring combined toxicities and interactions of groups of substances. However, in the real world, “co-exposure” is the norm as pollutants seldom present individually but rather as complex mixtures with other pollutants.

In a recent study published in Environmental Science and Ecotechnology titled, “Combined effect of microplastic and triphenyltin: insights from the gut-brain axis,” researchers from Shandong University, China, and the Chinese Academy of Sciences examined the combined toxicity of these common pollutants on the gut-brain axis using the “common carp” as a model organism. Their study provides a theoretical basis for evaluating the “coexistence risk” of such pollutants.   

The interplay of environmental pollutants

Microplastics — variously shaped plastic particles of sizes smaller than 5 millimetres — have been found in water sources around the globe, including polar ice and deep ocean basins. They represent a global pollution problem inversely proportional to their size. Triphenyltin (TPT) – an organotin compound widely used in manufacturing and industry – is being found in high levels in coastal waters.

Sewage sludges and wastewaters bring high concentrations of microplastics in contact with other environmental pollutants, such as TPT. In such biochemical slurries, microplastics  provide large surface areas for adsorption or attachment, becoming carriers for other chemicals and substances. Even the most effective wastewater treatment processes don’t remove microplastics completely. When released into the environment, carrier microplastics mimic the appearance of some natural food items of aquatic species, get ingested, and then deliver adsorbed pollutants directly to their digestive tracts.

Acting alone, microplastics can imbalance intestinal flora, change the structure of intestinal villi, and alter the gut mucosa. They also accumulate in brain tissues, damaging the blood-brain barrier. Since dietary accumulation is an important pathway, the researchers examined how this toxicity manifests upon the “gut-brain axis” – an intricate “information exchange system between the brain and gut, consisting of the neuroendocrine, vagal, and immune pathways.”

The study design

The authors conducted exposure experiments with juvenile common carp — a widely cultured freshwater fish — using realistic environmental concentrations of both pollutants, microplastics and TPT. One group was exposed to each pollutant singly, while a third group was exposed to a combination of both pollutants. The experiments lasted 42 days, and the fish were sampled at regular intervals to evaluate combined toxicity effects on “gut physiology, biochemical parameters, gut microbial 16S rRNA, and brain transcriptome sequencing.”

Results

The study detected that the pollutants both when acting singly, and in combination,

had toxic manifestations for the carp’s gut-brain axis, but with important differences. When acting alone, microplastics mainly suppressed immunity, while TPT interfered with lipid metabolism. However, when combined, TPT amplified the immunotoxicity of microplastics.

Histopathological examination showed that exposure to both microplastics and TPT increased the area and density of gut glycoproteins, an immunomodulatory component of intestinal mucus secreted by goblet cells, when compared to controls and single pollutants. The authors explain this as, “the gut having protected itself against foreign microplastics and TPT by stimulating glycoprotein secretion to improve the functioning of the intestinal barrier.”

Further biochemical assessments and genetic sequencing of the carp’s gut microflora and brain tissues provided further evidence of amplified toxicity under co-exposure. 16s-rDNA sequencing of the gut microbiome coupled with Kyoto Encyclopaedia of Genes and Genomes (KEGG) analyses showed an increased complexity of the bacterial network under co-exposure, with a reduced abundance of genera important for proper immune functioning. This could contribute to increased glycoprotein levels as compensatory mechanism to maintain immune functioning.

Examining the carp’s brain with transcriptome analysis to detect differentially expressed genes (DEGs), they found that microplastics acting alone mainly decreased some DEGs related to immune functioning, while TPT combined with microplastics reduced the expression levels of the same genes related to immunity significantly more. TPT alone increased lipid metabolism DEGs levels. This finding led them to conclude that, “the combination of microplastics and TPT amplifies the immunotoxicity of microplastics acting alone.”

A correlation analysis of gut parameters with carp brain metabolism genes for both immunity and lipid metabolism pathways further showed that the abundance of bacteria in the intestine of carp was significantly correlated with expression levels of DEGs in the carp brain related to immunity, while little correlation was present with lipid metabolism genes, providing a consistent story on how TPT amplifies the toxicity of microplastics on the carp’s immune system via the gut-brain communication channel.

Conclusion and Next Steps

These findings underscore the complex interplay between pollutants and environmental health.

As the authors note, “This study provides new insights from the perspective of the gut-brain axis and finds that immune-related DEGs are significantly associated with gut-dominant microbes and immune parameters, but the (underlying) mechanisms require further investigation.”

Continued research in this area will contribute to our understanding of the environmental and health implications of combined exposure to common pollutants and support the development of strategies to mitigate their adverse effects on ecosystems and human well-being.

JOURNAL

Environmental Science and Ecotechnology

DOI

10.1016/j.ese.2023.100266 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Combined effect of microplastic and triphenyltin: Insights from the gut-brain axis

ICYMI!

Greenhouse gas emissions at ‘an all-time high’ causing unprecedented rate of global warming - global scientists

Human-caused global warming has continued to increase at an “unprecedented rate” since the last major assessment of the climate system published two years ago, say 50 leading scientists.

Peer-Reviewed Publication

MAYNOOTH UNIVERSITY

 

IMAGE: INFOGRAPHIC SHOWING HEADLINE RESULTS FROM INDICATORS OF GLOBAL CLIMATE CHANGE 2022: ANNUAL UPDATE OF LARGE-SCALE INDICATORS OF THE STATE OF THE CLIMATE SYSTEM AND THE HUMAN INFLUENCE. “AR6” REFERS TO APPROXIMATELY 2019 AND “NOW” REFERS TO 2022. CREDIT: IGCC. view more 

CREDIT: CREDIT: IGCC.

Human-caused global warming has continued to increase at an “unprecedented rate” since the last major assessment of the climate system published two years ago, say 50 leading scientists. 

One of the researchers said the analysis was a “timely wake-up call” that the pace and scale of climate action has been insufficient. It comes as climate experts meet in Bonn to prepare the ground for the major COP28 climate conference in the UAE in December, which will include a stocktake of progress towards keeping global warming to 1.5°C by 2050. 

Professor Peter Thorne, Director of ICARUS Climate Research Centre at Maynooth University, said: “It is critical that policy makers and the general public be made aware of how quickly we are changing the climate through our collective activities. Already since the IPCC assessment of the physical science basis in 2021, key numbers have changed markedly and we remain well off track globally to avert warming above 1.5 degrees.”

Given the speed at which the global climate system is changing, the scientists argue that policymakers, climate negotiators and civil society groups need to have access to up-to-date and robust scientific evidence on which to base decisions. 

The authoritative source of scientific information on the state of the climate is the UN’s Intergovernmental Panel on Climate Change (IPCC) but the turnaround time for its major assessments is five or ten years, and that creates an “information gap”, particularly when climate indicators are changing rapidly.

In an initiative led by the University of Leeds with researchers from around the world, including Maynooth University ICARUS Director, Professor Peter Thorne, the scientists have developed an open data, open science platform - the Indicators of Global Climate Change and website (https://igcc.earth/). It will update information on key climate indicators every year.

Critical decade for climate change

The Indicators of Global Climate Change Project is being co-ordinated by Professor Piers Forster, Director of the Priestley Centre for Climate Futures at Leeds. He said: “This is the critical decade for climate change. 

 “Decisions made now will have an impact on how much temperatures will rise and the degree and severity of impacts we will see as a result. 

“Long-term warming rates are currently at a long-term high, caused by highest-ever levels of greenhouse gas emissions. But there is evidence that the rate of increase in greenhouse gas emissions has slowed.

“We need to be nimble footed in the face of climate change. We need to change policy and approaches in the light of the latest evidence about the state of the climate system. Time is no longer on our side. Access to up-to-date information is vitally important.”

Writing in the journal Earth System Science Data, the scientists have revealed how key indicators have changed since the publication of the IPCC’s Sixth Assessment Working Group 1 report in 2021- which produced the key data that fed into the subsequent IPCC Sixth Synthesis Report.

What the updated indicators show

Human-induced warming, largely caused by the burning of fossil fuels, reached an average of 1.14°C for the most recent decade (2013 to 2022) above pre-industrial levels. This is up from 1.07°C between 2010 and 2019.

Human-induced warming is now increasing at a pace of over 0.2°C per decade.

The analysis also found that greenhouse gas emissions were “at an all-time high”, with human activity resulting in the equivalent of 54 (+/-5.3) gigatonnes (or billion metric tonnes) of carbon dioxide being released into the atmosphere on average every year over the last decade (2012-2021).

There has been positive move away from burning coal, yet this has come at a short-term cost in that it has added to global warming by reducing particulate pollution in the air, which has a cooling effect. 

‘Indicators critical to address climate crisis’

Professor Maisa Rojas Corradi, Minister of the Environment in Chile, IPCC author and a scientist involved in this study, said: “An annual update of key indicators of global change is critical in helping the international community and countries to keep the urgency of addressing the climate crisis at the top of the agenda and for evidence-based decision-making.

“In line with the “ratchet-mechanism” of increasing ambition envisioned by the Paris Agreement we need scientific information about emissions, concentration, and temperature as often as possible to keep international climate negotiations up to date and to be able to adjust and if necessary correct national policies.

“In the case of Chile, we have a climate change law that aims at aligning government-wide policies with climate action.”

Remaining carbon budget

One of the major findings of the analysis is the rate of decline in what is known as the remaining carbon budget, an estimate of how much carbon that can be released into the atmosphere to give a 50% chance of keeping global temperature rise within 1.5°C. 

In 2020, the IPCC calculated the remaining carbon budget was around 500 gigatonnes of carbon dioxide. By the start of 2023, the figure was roughly half that at around 250 gigatonnes of carbon dioxide. 

The reduction in the estimated remaining carbon budget is due to a combination of continued emissions since 2020 and updated estimates of human-induced warming. 

Professor Forster said: “Even though we are not yet at 1.5°C warming, the carbon budget will likely be exhausted in only a few years as we have a triple whammy of heating from very high CO2 emissions, heating from increases in other GHG emissions and heating from reductions in pollution.

“If we don’t want to see the 1.5°C goal disappearing in our rearview mirror, the world must work much harder and urgently at bringing emissions down.

“Our aim is for this project to help the key players urgently make that important work happen with up-to-date and timely data at their fingertips.” 

Dr Valérie Masson-Delmotte, from the Université Paris Saclay who co-chaired Working Group 1 of the IPCC’s Sixth Assessment report and was involved in the climate indicators project, said: “This robust update shows intensifying heating of our climate driven by human activities. It is a timely wake up call for the 2023 global stocktake of the Paris Agreement - the pace and scale of climate action is not sufficient to limit the escalation of climate-related risks.”

As recent IPCC reports have conclusively shown, with every further increment of global warming, the frequency and intensity of climate extremes, including hot extremes, heavy rainfall and agricultural droughts, increases.

The Indicators of Global Climate Change (https://igcc.earth/) will have annually updated information on greenhouse gas emissions, human-induced global warming and the remaining carbon budget. 

The website extends a successful climate dashboard called the Climate Change Tracker which was created by software developers who took ideas from the finance industry on how to present complex information to the public. 

What the analysis revealed

Climate Indicator	Sixth Assessment Report (AR6)	Latest value
Greenhouse gas emissions (decadal average)	53 GtCO2e (2010-2019)	54 Gt CO2e (2012-2021)
Human-induced warming since preindustrial times	1.07°C	1.14°C
Remaining carbon budget (1.5C, 50% chance)	500 GtCO2	About 250 GtCO2 and very uncertain

Headline results from the paper Indicators of Global Climate Change 2022: Annual update of large-scale indicators of the state of the climate system and the human influence.  “AR6” refers to approximately 2019 and “Now” refers to 2022.  The AR6 period decadal average greenhouse gas emissions are our re-evaluated assessment for 2010-2019.

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JOURNAL

Earth System Science Data

DOI

10.5194/essd-15-2295-2023 

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Indicators of Global Climate Change 2022: annual update of large-scale indicators of the state of the climate system and human influence

ARTICLE PUBLICATION DATE

8-Jun-2023

Untapping barley’s grain yield potential by mitigating floral degeneration

Peer-Reviewed Publication

LEIBNIZ INSTITUTE OF PLANT GENETICS AND CROP PLANT RESEARCH

 

IMAGE: THE AIM IS TO BETTER DEVELOP THE YIELD POTENTIAL OF THE CEREAL PLANT. view more 

CREDIT: IPK LEIBNIZ INSTITUTE/ T. SCHNURBUSCH

Barley possesses an indeterminate 'spike'-type inflorescence that forms basic floral structures, called spikelets, in a distichous pattern along its central axis (termed rachis). Each rachis node in the barley spike produces three (one central and two lateral) spikelets.

At the end of spikelet primordia initiation along the rachis marks the stage of maximum yield potential. Subsequently, the inflorescence meristem dome starts to collapse, followed by gradual basipetal degeneration of spikelet primordia and spikelets until a specific position along the spike is reached. “We show that up to 50% of the initiated floral primordia are aborted before anthesis, representing an untapped yield potential”, says
Prof. Dr. Thorsten Schnurbusch, head if IPK’s research group “Plant Architecture”. “Understanding the molecular underpinnings of spike PTD may thus help improve grain yield in cereals.”

Due to its quantitative nature and environmental sensitivity, inflorescence PTD constitutes a complex mechanism affecting final grain number. This mechanism appears to be predictable and heritable, consistent with a developmental programme. Photosynthesis, immature spike greening, and energy metabolism appear to be significant contributors to proper spikelet growth and differentiation and were restricted to basal and central spike parts. The researchers discovered, however, that the degenerating apical spike region undergoes sugar and amino acid depletion along with enhanced abscisic acid biosynthesis and signaling.

“Moreover, we functionally validated one of the apically expressed transcription factor genes, barley GRASSY TILLERS1 (HvGT1) an ortholog of maize GT1, as a growth repressor of apical spikelet development”, emphasises Nandhakumar Shanmugaraj, first author of the study. Site-directed Hvgt1 mutants in barley delayed the onset of spike PTD and produced more differentiated apical organs, resulting in significantly more fertile spikelets/florets and increased final spikelet number. “This is the first report on the molecular underpinnings of barley inflorescence PTD; however, here we not only provide a molecular framework for barley but also for related cereals of the Triticeae tribe (e.g., wheat, rye).”

“We believe that the molecular elucidation of PTD in barley will also stimulate future research directions on the evolution of related genes on growth suppression in other plants beyond crop species”, says Prof. Dr. Thorsten Schnurbusch. As barley is amongst the most important cereal crops in the world, better exploiting its spike yield potential can thus contribute to world food security and thereby directly help fight against hunger threats imposed by climate change, and natural or war disasters.

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JOURNAL

The Plant Cell

DOI

10.1093/plcell/koad164 

ARTICLE TITLE

Multilayered regulation of developmentally programmed pre-anthesis tip degeneration of the barley inflorescence

ARTICLE PUBLICATION DATE

7-Jun-2023

Scientists map complete genome of millet

New knowledge of ancient grain may enable breeding for climate change adaptation

Peer-Reviewed Publication

NEW YORK UNIVERSITY

An international team of researchers has unlocked a large-scale genomic analysis of Setaria or foxtail millet, an important cereal crop. The study, led by researchers at the Chinese Academy of Agricultural Sciences and including scientists at NYU, advances our understanding of the domestication and evolution of foxtail millet, as well as the genetic basis for important agricultural traits.

 

“Foxtail millet is considered to be the foundation for early Chinese civilization,” said Michael Purugganan, the Silver Professor of Biology at NYU and NYU Abu Dhabi, and the study’s co-senior author. “Moreover, because it is a crop that can grow across a wide range of environments—including arid lands—it has the potential to be important for food security under climate change.”

 

Foxtail millet is one of the oldest domesticated grain crops in the world and has been grown by humans for roughly 11,000 years. It held a dominant position in Chinese agriculture before the introduction of high-input agricultural practices like irrigation and chemical fertilizers. The protein-rich grain—which employs C4 photosynthesis, a highly efficient form of photosynthesis that helps it adapt to different environments—is resilient to drought and able to thrive in low-nutrient soils.

 

“C4 plants constitute only about 3% of flowering plant species, but they surprisingly contribute to approximately 25-30% of global biomass production. The complexity of the genomes of most C4 species has posed challenges for fundamental studies and breeding, but Setaria serves as an ideal model system for studying C4 photosynthetic plants in genomics and genetics research,” said Xianmin Diao, a professor in the Institute of Crop Sciences at the Chinese Academy of Agricultural Sciences, the study’s co-senior author, and the scientist who organized the study.

 

In their study published in the journal Nature Genetics, the researchers established the Setaria pan-genome—the entire set of the species’ genes—by assembling 110 representative genomes from a worldwide collection of 1,844 Setaria species. They performed large-scale genetic studies for 68 traits across 22 environments in 13 geographical locations, each with distinct climactic conditions, identifying potential genes and marker-panels for how foxtail millet has evolved and improved at different geographic sites. For instance, the researchers found that the gene SiGW3 regulates grain yield of foxtail millet.

 

They also constructed the first graph-based genome sequence of Setaria, offering insights into genomic variation across wild and cultivated Setaria. This deeper understanding of the comprehensive genomic variation equips researchers with valuable genetic tools to pursue biological research and breeding efforts.

 

“This paper is a significant milestone, as it paves the way for the next generation of comparative genomics studies that can help to decipher the molecular mechanism of C4 photosynthesis. The large-scale comparative genomics, genome-wide association study, and genomic selection studies of Setaria not only provide opportunities for gene discovery and breeding advancements in foxtail millet itself, but also offer insights for other crops to enhance global food security,” added Diao.

 

“Understanding the genetic basis underlying the domestication and improvement of foxtail millet, along with these important agricultural characteristics, holds significant potential for its enhancement. With our graph-based genome, we can estimate grain quality-related traits and potential yield, providing avenues for foxtail millet breeding for climate change adaptation,” said Qiang He, a postdoctoral researcher in the Institute of Crop Sciences at the Chinese Academy of Agricultural Sciences and the study’s first author.

 

Purugganan’s research was supported by grants from the National Science Foundation Plant Genome Research Program (IOS-1546218 and 2204374), the Zegar Family Foundation, and the NYU Abu Dhabi Research Institute.

 

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JOURNAL

Nature Genetics

DOI

10.1038/s41588-023-01423-w 

ARTICLE TITLE

A graph-based genome and pan-genome variation of the model plant Setaria

ARTICLE PUBLICATION DATE

8-Jun-2023

Scientists discover how plants fight major root disease

Peer-Reviewed Publication

CHINESE ACADEMY OF SCIENCES HEADQUARTERS

 

IMAGE: WTS ENCODES AN ER-LOCALIZED CA2+ RELEASE CHANNEL, TRIGGERING IMMUNE RESPONSE TO PROTECT STELE FROM P. BRASSICAE INVASION view more 

CREDIT: CHENG HANGYUAN

Researchers led by CHEN Yuhang and ZHOU Jianmin from the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences have shown how plants resist clubroot, a major root disease that threatens the productivity of Brassica crops such as rape.

The study, which uncovers novel mechanisms underlying plant immunity and promises a new avenue for crop breeding, was published in Cell.

Clubroot, a soil-borne disease, is the most devastating disease of Brassica crops. In China, approximately 3.2–4 million hm2 of agricultural land is affected by clubroot each year, resulting in a 20%–30% yield loss. Resting spores of Plasmodiophora brassicae (Pb), the causal pathogen of clubroot, are viable in soil for up to 20 years, making contaminated soil unsuitable for Brassica crops.

To date, only two clubroot resistance genes have been cloned, and their resistance has broken down as a result of newly evolved virulent Pb isolates.

In this study, the newly identified resistance gene WTS confers resistance to all Pb isolates tested, including isolates that are virulent toward existing resistant rape varieties. Thus, WTS is a broad-spectrum resistance gene and offers great potential for breeding clubroot disease resistance in crops.

WTS is not expressed in the absence of the pathogen. However, upon Pb infection, WTS is strongly induced exclusively in the pericycle, a critical layer of root cells surrounding the stele. The stele is the cylindrical central vascular portion of root containing critical tissues, including xylem and phloem that are essential for nutrient and water transport.

In susceptible plants, Pb invades and colonizes the stele, blocking nutrient and water transport. Expression of WTS in the pericycle activates plant defenses and prevents Pb from colonizing the stele. WTS thus defines a defense mechanism that is specifically activated at the right place and right time to ensure normal plant growth and development.

In addition, WTS encodes a novel protein. Structural analysis by cryo-EM has revealed that WTS self-assembles into a previously unknown pentameric architecture with a central pore.

Further studies have also shown that the WTS protein complex functions as an endoplasmic reticulum-localized calcium release channel that increases cytosolic calcium ions, a critical secondary signal for the activation of plant defenses.

The intriguing disease resistance mechanisms uncovered by the researchers represent a new paradigm in plant immunity against soil-borne pathogens. The cloned WTS gene offers new hope for breeding Brassica crops resistant to a devastating disease that is otherwise difficult to control.

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JOURNAL

Cell

DOI

10.1016/j.cell.2023.05.023 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

WeiTsing, a pericycle-expressed ion channel, safeguards the stele to confer clubroot resistance

ARTICLE PUBLICATION DATE

8-Jun-2023

Team finds reliable predictor of plant species persistence, coexistence

Peer-Reviewed Publication

UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN, NEWS BUREAU

 

IMAGE: U. OF I. PLANT BIOLOGY PROFESSOR JAMES O’DWYER, PICTURED, AND GRADUATE STUDENT KENNETH JOPS DEVELOPED A METHOD FOR PREDICTING WHETHER PAIRS OR GROUPS OF PLANTS ARE LIKELY TO PERSIST TOGETHER IN A HABITAT OVER TIME. view more 

CREDIT: PHOTO BY MICHELLE HASSEL

CHAMPAIGN, Ill. — Like many ecological scientists, University of Illinois Urbana-Champaign plant biology professor James O’Dwyer has spent much of his career searching for ways to measure and predict how specific plant communities will fare over time. Which species in a diverse population will persist and coexist? Which will decline? What factors might contribute to continuing biodiversity?

In a new study reported in the journal Nature, O’Dwyer and his colleague, U. of I. graduate student Kenneth Jops, report the development of a method for determining whether pairs or groups of plant species are likely to coexist over time. Using data from published studies, their approach reliably predicts the complementary life histories of pairs of plants that – while competing for many of the same resources – manage to thrive in a shared habitat.

The method relies on the painstaking collection of years of data about each species, O’Dwyer said.

“Over the last 50 or so years, people have gathered more and more data about plant life histories, your death rates, your reproductive rates, how many seeds you’re producing, how quickly you grow into the next life stage – and all of that can be changing throughout your lifespan,” he said. “And we write this as a matrix that roughly describes all those aspects of life history – and it’s different for every species.”

Certain elements of the matrix are plugged into an equation that yields the “effective population size,” a number that is recorded in units of years. The key finding in the new study is that if two plant species have roughly equivalent effective population sizes, they are more likely to coexist over time.

Jops first saw patterns in the data gathered for species found in the same habitat, “but it took us a while to make sense of the patterns,” O’Dwyer said.

An equal or near-equal EPS means that “there’s something about the way that the life histories jigsaw together that makes it more likely that they will persist,” O’Dwyer said.

The EPS equation reflects a mathematical relationship between the number of new individuals “born” each year, the average age of the parents, and the plant’s reproductive success over its lifetime, the researchers said.

The team found that a larger EPS also coincided with a better outcome for the species.

The data set the team used in the new study is relatively small, O’Dwyer said.

“There are around 800 to 1,000 plant species in the database we use – a drop in the ocean of plant diversity,” he said. Further research will test the new method on larger data sets involving more plants in more types of habitats, the researchers said.

“Plant biodiversity is a huge and complex question and I’m glad we were able to shed some light on how life history fits into that puzzle,” Jops said. “I hope this will encourage researchers to collect life history data across larger communities so we can apply our theory along with niche, fitness differences and environmental factors to better explain biodiversity patterns across the globe.”

The Simons Foundation and James S. McDonnell Foundation supported this research.

 

Editor’s note:  

To reach James O’Dwyer, email jodwyer@illinois.edu  
To reach Kenneth Jops, email kjops2@illinois.edu

The paper “Life history complementarity and the maintenance of biodiversity” is available online or from the U. of I. News Bureau.
 

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JOURNAL

Nature

DOI

10.1038/s41586-023-06154-w 

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Life history complementarity and the maintenance of biodiversity

ARTICLE PUBLICATION DATE

7-Jun-2023

Study finds socially tolerant monkeys have better impulse control

Socially tolerant species are better at controlling their emotions and behaviours, according to a new study of one of humanity's closest relatives

Peer-Reviewed Publication

UNIVERSITY OF PORTSMOUTH

 NEWS RELEASE 8-JUN-2023

Researchers have tested one of the ideas put forward to explain how humanity evolved to become smarter, on non-human primates.

The study, led by a team at the University of Portsmouth, found a significant connection between social organisation and cognitive skills in monkeys. 

They assessed three species of macaques with different social tolerance levels, from authoritarian to more relaxed societies, in a series of cognitive touchscreen touchscreen tasks to work out how impulsive and reactive they were.

Tonkean macaques, which are known to get along with each other the most with more diverse and complex relationships, demonstrated better overall control of distraction, emotions and actions compared to the less-tolerant long-tailed and rhesus species. 

Lead author and PhD researcher, Dr Louise Loyant from the University of Portsmouth’s Centre of Comparative and Evolutionary Psychology (CCEP), said: “This relationship between social tolerance and cognitive abilities could explain why Tonkean macaques are better at managing complex relationships with others.

“This is important, as it improves our understanding of our own social evolution. Macaques live in complex communities, not too dissimilar from our own, and we can learn a lot from them.

“Existing research on human inhibitory control, or self-control, suggests the better a person is at managing their emotions and reactions, the more successful they’re likely to be in life; whether that be in relationships, work, or just generally. Our results support this hypothesis.”

The study, published in Animal Cognition, also highlighted the influence of ecological factors on self-control skills. Different risks and environmental pressures faced by each species might have shaped their behaviours, emotions, and impulsivity levels.

Long-tailed and rhesus macaques living in areas with a greater number of predators, displayed more reactive and cautious behaviours, while Tonkean macaques who face lower predatory risk, exhibited quieter and less reactive behaviours.

The researchers say that both social and ecological factors may jointly influence self-control skills in primates.

Senior co-author, Dr Marine Joly from the CCEP, explained: “A macaque living in a more competitive environment would benefit from learning how to contain inappropriate behaviours, like feeding or mating, if they’re around others higher up in the social pyramid. 

“But there’s also the hypothesis that our closest primate species have evolved over time to have increased brain size and higher cognitive performances, including better self-control. 

“Our findings support both of these potential explanations, as well as suggest that species living in more complex societies might have better socio-cognitive skills too, including perception, attention, memory and action planning.”

The team evaluated the performance of 66 macaques from two institutions, the Medical Research Council Centre for Macaques in the UK and the Centre of Primatology of the University of Strasbourg in France.

While the study provides valuable insights, the researchers acknowledge some limitations, including the sample size and some prior cognitive testing experiences among the species. They recommend further research involving a larger number of macaques, as well as a closer evaluation of an individual’s reactions and results.

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JOURNAL

Animal Cognition

DOI

10.1007/s10071-023-01789-8 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Tolerant macaque species are less impulsive and reactive