Wednesday, August 20, 2025

Access to green space was a mental health lifeline during COVID-19 pandemic

New Canadian national study highlights how neighbourhood green space protected mental health—especially for vulnerable populations

University of Toronto

Toronto, ON — A new national study led by researchers from Carleton University and the University of Toronto reveals that older adults living in greener neighborhoods were less likely to experience depression during the early months of the COVID-19 pandemic.

Using data from over 13,000 urban-dwelling participants in the Canadian Longitudinal Study on Aging (CLSA), researchers found that access to nearby green spaces — from public parks and playing fields to tree canopy cover and private gardens along neighbourhood streets — may act as a mental health buffer, especially for those without a prior history of depression, those with fewer economic resources and those with mobility limitations.

The study uncovered four main findings.

Urban areas with more vegetation were associated with lower rates of depression during the Pandemic. People who were not depressed before COVID-19 but lived in greener neighborhoods were significantly less likely to develop depression.

“Urban greenery wasn’t just a backdrop — it played a protective mental health role in one of the most stressful global events in recent history,” said Dr. Paul J. Villeneuve, lead author and Professor in the Department of Neuroscience, Carleton University, Canada.

Living in green neighbourhoods was especially protective for lower-income Canadians. The mental health benefits of residential greenness, which was determined by satellite data, were more pronounced among people with lower wealth — especially those who were not previously depressed.

“Our findings suggest that green spaces may have played a modest, yet meaningful, role in supporting the mental well-being of lower-income Canadians during the pandemic, offering some relief amid deepening socio-economic inequities,” said co-author Susanna Abraham Cottagiri, doctoral candidate at the School of Medicine at Queen’s University.

People with mobility challenges gained more from living in greener neighbourhoods. Among individuals without pre-existing depression, those with mobility issues saw stronger benefits from greenness — possibly because their access to more distant green spaces were restricted.

“When mobility is limited, the greenery right outside your door may play a particularly important role in supporting mental health and well-being,” said co-author Dr. Ying Jiang, Senior Epidemiologist at the Public Health Agency of Canada.

People who, prior to the pandemic, had rarely visited places in their neighbourhood outside their own yard saw a greater protective effect from living in greener neighbourhoods during the pandemic. The less one ventured out prior to the pandemic, the more the presence of greenery and green spaces in their neighbourhood positively impacted their mental health during the pandemic.

“It appears that the psychological value of green space may increase when social connections are restricted,” said Dr. Margaret de Groh, study co-author.

The authors suggest that the findings call for a rethinking of urban planning and mental health policy in Canada.

“There is a need to expand equitable access to green space, particularly in lower-income neighborhoods, to protect and preserve local greenery, even during public health emergencies, and to integrate green infrastructure into mental health resilience strategies,” said co-author Professor Esme Fuller-Thomson at the University of Toronto’s Factor-Inwentash Faculty of Social Work and director of the Institute for Life Course & Aging.

This study is one of the few longitudinal analyses of mental health and green space during the pandemic. The researchers drew on satellite data to assess greenness and determine its link to validated depression measures across two time points: pre-pandemic and six months into the pandemic.

The study also sheds light on under-explored issues, such as how socioeconomic status, mobility limitations, and social behavior influence the mental health benefits of greenery. However, the authors caution that some of the most vulnerable Canadians — such as those in long-term care — were not represented in their sample.

About the Study

The peer-reviewed study, “Residential Greenness Reduced Depression During COVID-19: Longitudinal Analyses from the Canadian Longitudinal Study on Aging (CLSA)”, involved researchers from Carleton University, the University of Toronto, Queen’s University, and the Public Health Agency of Canada.

Journal

PLOS One

DOI

10.1371/journal.pone.0329141

Method of Research

Survey

Subject of Research

People

Article Title

Residential Greenness Reduced Depression During COVID-19: Longitudinal Analyses from the Canadian Longitudinal Study on Aging (CLSA)

Article Publication Date

20-Aug-2025

In the Neolithic, agriculture took root gradually

A UNIGE study shows that European hunter-gatherers and Anatolian farmers coexisted and gradually interbred.

Université de Genève

The transition to agriculture in Europe involved the coexistence of hunter-gatherers and early farmers migrating from Anatolia. To better understand their dynamics of interaction, a team from the University of Geneva (UNIGE), in collaboration with the University of Fribourg and Johannes Gutenberg University, Mainz, combined computer simulations with ancient genetic data. The results show that population mixing increased locally over time during the Neolithic expansion, at each stage of the farmers’ advance along the “Danube route” toward Central Europe. Published in Science Advances, the study offers new insight into this pivotal period in human history.

The shift from a hunter-gatherer lifestyle to an agricultural one marked a major turning point in human history. In Europe, this transition began almost 9,000 years ago, with the migration of farmers from the Aegean region and western Anatolia (modern-day Anatolian Turkey), who followed the “Danube route” eventually reaching Central Europe (present-day northern Germany). Before the hunter-gatherer lifestyle was fully replaced, the two cultures coexisted for several generations.

Scientists have long debated whether this transition occurred through knowledge transfer from nearby farming communities or through interbreeding between the populations as the farmers migrated. Archaeological evidence – such as the coexistence of cultural artifacts from both groups – combined with paleogenomic analysis of well-preserved human remains, has confirmed the hypothesis of population migration and admixture.

Modeling the Encounter Between Two Worlds

In this study, the group led by Mathias Currat, senior lecturer in the Department of genetics and evolution at UNIGE’s Faculty of science, aimed to better understand how these populations interacted over time. The team focused on the demographic dynamics along the “Danube route”: did the groups intermingle consistently from the outset, or did the mixing intensify over time? Using computer models, the researchers simulated the Neolithic expansion by incorporating geographic positions, biological parameters (such as population sizes, reproduction rates, and migration patterns), and interaction variables (like genetic admixture rates and potential competition).

“These simulations generated thousands of genetic scenarios, which we then compared to data from 67 prehistoric individuals from regions where the two groups had coexisted. By applying statistical methods, we were able to estimate the most likely demographic parameters,” explains Mathias Currat. The findings reveal that at each stage of the farmers’ expansion toward northwestern Europe, genetic mixing with hunter-gatherers was initially rare but increased locally over time. “Our results show that the Neolithic transition was not characterized by violent confrontation or complete replacement, but rather by prolonged coexistence with increasing levels of interbreeding,” adds Alexandros Tsoupas, a researcher in Currat’s team and first author of the study.

More Numerous and More Mobile Farmers

The study also estimates the demographic advantage of early farmers: their effective population size was roughly five times larger than that of the hunter-gatherers. Although rare, some farmers made long-distance “migration jumps,” helping to accelerate their expansion into central Europe.

These findings provide a nuanced answer to a longstanding debate: the Neolithization of Europe was not a simple colonization process, but a complex one involving contact, cohabitation, and gradually increasing admixture. The study also highlights the power of combining ancient genetics with modeling approaches to reconstruct key chapters of human history.

Journal

Science Advances

DOI

10.1126/sciadv.adq9976

Outsmart an island fox? Not so fast

Challenging long-held ideas of evolution on islands, a USC Dornsife study found most Channel Islands foxes evolved proportionally larger brains than their mainland cousins — a surprising trait shaped by novel, isolated conditions and survival demands.

University of Southern California

Skull scans of fox skulls — image:
Researchers scanned island fox skulls to create digital models, enabling them to calculate brain and body size.
view more
Credit: Nick Neumann/USC Wrigley Institute.

For decades, scientists believed animals on islands evolved smaller brains relative to body size to save energy. But most Channel Islands foxes — tiny predators no bigger than a house cat – defied that rule, evolving larger brains than their mainland cousins.

The findings, published in PLOS One by researchers at the USC Dornsife College of Letters, Arts and Sciences, suggest brain size may hinge less on isolation and more on the demands of survival.

Island syndrome refers to a suite of traits including reduced size, brain shrinkage, loss of flight in birds and tamer behavior. Until now, island brain size has been mainly studied in fossils of herbivores, which face different pressures than carnivores. The island fox provided an opportunity to bridge that research gap.

Lead author Kimberly Schoenberger said the results upend long-held assumptions about how animals adapt to island life. “It was most surprising to discover that island syndrome isn’t one-size-fits-all,” said Schoenberger, a PhD candidate in biology. “When we looked at carnivores like Channel Island foxes, the pattern of smaller brains didn’t hold.”

Channel Islands offer a natural experiment

The Channel Islands, an eight-island chain off the California coast, six of which are home to foxes, offered researchers a rare natural experiment to test whether island syndrome holds true across environments. The biologists compared the brains of foxes from those six islands with mainland gray foxes — their closest living relatives and likely ancestors — as well as with one another.

The analysis revealed that the brain-to-body ratio appeared to be shaped less by isolation or island size alone — long thought to drive island syndrome — and more by local habitat conditions.

On five of the islands — Santa Cruz, Santa Rosa, Santa Catalina, San Clemente and San Miguel — foxes had relatively larger brains despite their smaller bodies. Their brains also showed slightly deeper folds and ridges in areas tied to motor control and spatial processing, traits that may help the foxes navigate rugged terrain and compete for food and shelter, especially on two islands where they share space with rivals like the spotted skunk.

San Nicolas Island, the most remote and resource-limited of the six, was the exception. There, foxes had smaller relative brain sizes. With no predators, little biodiversity and limited food, researchers believe the animals faced fewer cognitive demands and may have conserved energy for basic survival rather than retaining traits like enhanced motor coordination or spatial processing.

“The Channel Island foxes show that brain size reduction is not a universal feature of island life,” Schoenberger said. “It depends on the pressures each species faces.”

Fox brains adapt to island living

To understand how brain size changed in the island fox, Schoenberger and research collaborators at the Natural History Museum of Los Angeles County (NHM) studied more than 250 skulls from six island fox subspecies and four mainland gray fox subspecies. The specimens came from collections at NHM and the Santa Barbara Museum of Natural History.

First, they estimated body weights from skull measurements, then compared those estimates to recorded weights from live island foxes. The two sets aligned closely, giving the team a solid basis for analyzing brain-to-body ratios. The brain size was measured using microbeads to approximate the internal volume of the skull, a highly accurate proxy for brain size.

Next, the researchers used CT scans to create 3D models of the skulls’ interiors. By capturing the shape and volume of the braincase — the hollow cavity that once housed the brain — they could confirm accuracy of the microbead brain size estimates and examine the structure of brain surface features such as folds and ridges imprinted on the inside of the skull.

The digital scans revealed a surprising feature: Island fox brains had shorter, more compact frontal areas than their mainland relatives. The researchers theorize that this likely relates to their shorter snouts, which reduce the brain space at the front of the skull. To compensate, these foxes developed slightly deeper folds and more pronounced ridges in this region. This preserves key motor control and spatial awareness skills particularly needed to climb trees and forage for food.

Schoenberger explained that while both the island and gray foxes are the only canines known to climb trees, island foxes relied more on foraging in trees compared to mainland foxes, which have more abundant food options on the ground.

The researchers also found that brain size didn’t differ between male and female foxes, suggesting that environmental pressures rather than mating competition were the likely drivers of these adaptations.

Island foxes were likely pest control, not pets

DNA and carbon dating suggest that foxes first arrived on the northern Channel Islands about 9,000 years ago, likely by riding natural debris rafts or swimming when sea levels were lower and distances between islands were shorter. Thousands of years later, archaeological evidence shows that Indigenous peoples may have transported foxes to otherislands, perhaps to help control pests.

Despite this long association with humans, island foxes likely never became truly domesticated — a fact researchers say may help explain why their brains did not shrink, as often happens in domestic species. In both brain size and behavior, they more closely resemble wildcats than early domestic dogs, which had already begun to lose brain volume as they grew dependent on people.

Broader lessons from island-bound foxes

As climate change and habitat loss create more fragmented, island-like environments, understanding which traits help animals adapt could guide conservation efforts. The island fox suggests that intelligence and cognitive flexibility may play a key role in survival but may only be an option if their habitat has enough natural resources.

Still, their future is uncertain. Previous research found that low genetic diversity could leave the foxes especially vulnerable to new threats such as disease, raising concerns about how well they’ll weather the next wave of environmental change.

About the study

The study was funded by the USC Dornsife Wrigley Institute for Environment and Sustainability, the Offield Family Foundation and the USC Women in Science and Engineering Graduate Fellowship.

Journal

PLOS One

DOI

10.1371/journal.pone.0328893

Method of Research

Computational simulation/modeling

Subject of Research

Animals

Article Title

Increased brain size of the dwarf Channel Island fox (Urocyon littoralis) challenges “Island Syndrome” and suggests little evidence of domestication

Article Publication Date

20-Aug-2025

California's dwarf Channel Island foxes mostly have relatively bigger brains than their larger mainland gray fox cousins, which may reflect island-specific evolutionary pressures

PLOS

Increased brain size of the dwarf Channel Island fox (Urocyon littoralis) challenges “Island Syndrome” and suggests little evidence of domestication — image:
A Channel Island fox stands among prickly pear cacti, a common dietary item for Santa Catalina foxes.
view more
Credit: Kimberly A. Schoenberger, CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

California's dwarf Channel Island foxes mostly have relatively bigger brains than their larger mainland gray fox cousins, which may reflect island-specific evolutionary pressures

Article URL: http://plos.io/4m6uyhk

Article title: Increased brain size of the dwarf Channel Island fox (Urocyon littoralis) challenges “Island Syndrome” and suggests little evidence of domestication

Author countries: U.S.

Funding: Funding for this project and Kimberly's PhD research was provided by Dornsife College of Letters, Arts and Sciences at the University of Southern California; the Wrigley Institute for Environmental Studies and Offield Family Foundation; and the USC Women in Science and Engineering Graduate Fellowship.

Schoenberger shows the size difference between a Channel Island fox skull (on left in photo) and a mainland gray fox skull (on right in photo).

Credit

Nick Neumann/USC Wrigley Institute, CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

Journal

PLOS One

DOI

10.1371/journal.pone.0328893

Article Title

Increased brain size of the dwarf Channel Island fox (Urocyon littoralis) challenges “Island Syndrome” and suggests little evidence of domestication

Article Publication Date

20-Aug-2025

LA REVUE GAUCHE - Left Comment: Search results for FOXES

LA REVUE GAUCHE - Left Comment: Search results for CANID

Hunting wolves reduces livestock deaths measurably, but minimally, according to new study

University of Michigan

Maps of wolves hunted by county in Northern Rocky states 2005 - 2020 — image:
These maps show snapshots of wolves hunted per county over time during the study period.
view more
Credit: From LM Merz et al., Sci. Adv., 2025 (DOI: 10.1126/sciadv.adu8945). This work is licensed under CC BY (https://creativecommons.org/licenses/by/4.0/).

Wolf hunting has prevented livestock loss in a measurable way, but it is by no means a silver bullet, according to an international research team led by the University of Michigan.

"Hunting, on the whole, is not removing negative impacts associated with wolves. It does have some effect on rates of livestock loss, but the effect is not particularly consistent, widespread or strong," said Neil Carter, associate professor at the U-M School for Environment and Sustainability and senior author of the new study published in the journal Science Advances.

As governmental protections have helped rebuild once-dwindling wolf populations, it's become increasingly likely that the predators encounter domesticated animals to prey on. Hunting is often presented as a remedy, but it's a contentious and polarizing proposal. Advocates on both sides of the issue have active lawsuits across the U.S. aiming to relax or redouble regulations.

But several northwestern states already allow hunting in some capacity, which has given researchers an opportunity to bring new information to the issue. The new study, supported by the U.S. National Science Foundation, showed that, on average, each wolf that was killed by a hunter was associated with a 2% reduction in predation.

The team also analyzed how hunting affected "lethal removals." These are expensive operations led by government agencies, targeting specific wolves, typically after multiple or severe predation events, said lead author Leandra Merz, assistant professor at San Diego State University.

Based on the team's study, hunting led to no reduction in lethal removals.

"We're not necessarily saying that we shouldn't be hunting and I want to be clear about that, because there are other motivations for hunting," said Merz, who worked on the project as postdoctoral scholar at U-M's School for Environment and Sustainability. "But if the goal is to reduce livestock predation and we're using hunting for that, it's not as effective as we would like."

The research team also included collaborators from the University of Idaho, Washington State University, Ohio State University and the GESIS Leibniz Institute for the Social Sciences in Germany. The researchers said this is an important part of a small but growing body of research that brings relevant information to a charged debate about wolf management strategies.

"A lot of uncertainty exists about the utility of public wolf hunting in reducing negative impacts from these animals as their populations recover," Carter said. "In an issue that's divisive and contentious, that uncertainty is something that we should try to minimize, because we could be making decisions that are just not as efficacious as they should be nor in the public’s best interest."

And out come the wolves

The Endangered Species Act, or ESA, has protected gray wolves across the contiguous U.S. for decades and, in the 1990s, the U.S. launched a successful wolf reintroduction campaign in the Northern Rocky Mountains. Within about 20 years, the Northern Rocky wolf population grew to where some states rolled out legalized hunting programs.

Since then, wolf hunting has been characterized by starts and stops driven by litigation brought by parties on both sides. In fact, in 2020, the U.S. Fish and Wildlife Service determined that gray wolf populations had recovered significantly enough to remove federal protections under the ESA before a court order reversed that decision in 2022. And the debate is far from over.

"There are timely things happening related to wolf management, both domestically and internationally," Carter said, pointing to Michigan and Europe as regions where the issue is especially being pressed. "Stakeholders involved in wolf management are bringing up the topic of hunting wolves and it's an imminent conversation we'll be having."

Yet the actual impact of wolf hunting on protecting livestock was unknown, meaning there have been a lot of assumptions involved in the discourse, Carter said. So he, Merz and their colleagues saw an opportunity to shed light on that using information from areas where wolf hunting was legal—Idaho and Montana—and from areas where wolf hunting was not legal, specifically Oregon and Washington.

The research analyzed data available for those areas from 2005 and 2021 using an array of mathematical models to connect hunting to its influence on depredation and lethal removal events. No hunting was permitted prior to 2009, helping researchers establish a control scenario.

Again, hunting showed no impact on the number of lethal removal operations, but predation was more nuanced. The average county in the analysis lost roughly 3 to 4 livestock animals per year to wolves. With the 2% reduction mentioned earlier, that translates to about 0.07 animals protected per wolf hunted, Carter said.

But the team also emphasized there can be huge variations from that average. For instance, Merz knows of an Idaho rancher that lost 65 sheep in one night to wolves. And a loss need not be that severe to have devastating economic consequences and steep psychological tolls.

"The cost can be really high to an individual rancher, even over very short time periods," Merz said. "We don't want to minimize that."

From a policy perspective, though, it's helpful to ask what are the best management methods to spread that cost effectively and equitably, Merz said. Hunting, as the study shows, relieves a minimal burden from ranchers, but at no direct cost to them.

Then there are nonlethal methods that are proving to be effective, Merz said, including fladry, a combination of flags and barriers that can be electrified. Even increasing the presence of humans or human activities helps (drones blasting AC/DC and arguments from the movie "Marriage Story" recently made news). But the cost of implementing and maintaining these measures almost exclusively falls on ranchers.

"There's not going to be an easy solution either way. If there were, we would have figured it out by now and we'd be using it," Merz said. "But the upside is that people are really creative. We just need to be a little bit more creative in how we redistribute some of the costs and benefits. I think outside of managing wildlife, we do that a lot in society."

These maps show snapshots of the geographic distribution of livestock lost to wolves per county over time during the study period.

Credit

From LM Merz et al., Sci. Adv., 2025 (DOI: 10.1126/sciadv.adu8945). This work is licensed under CC BY (https://creativecommons.org/licenses/by/4.0/)

Journal

Science Advances

DOI

10.1126/sciadv.adu8945

Article Title

Elusive effects of legalized wolf hunting

Article Publication Date

20-Aug-2025