Insights & Outcomes: Sea scorpions, delusions, and forensics-related stress

This month, our Yale research itinerary includes a “giant” discovery about ancient sea predators, an examination of health equity for LGBTQI+ communities, and new insights into how certain brain processes contribute to different types of delusions. We also look at some suggestions for improving health care sustainability metrics and an assessment of how stress affects forensic experts on the job.

As always, you can find more science and medicine research news on Yale News’ Science & Technology and Health & Medicine pages.

That’s a big eurypterid

Sea scorpions, ancient predators that patrolled Earth’s marine and freshwater habitats hundreds of millions of years ago, are the focus of a sizable scientific mystery.

Also known as eurypterids, these long-extinct relatives of modern-day horseshoe crabs, spiders, and scorpions sometimes grew to be more than two meters long and were, at their zenith about 430 million years ago, among the planet’s top predators. But paleontologists have debated over the cause of eurypterids’ gigantism — speculating that it had to do with everything from water temperature to changes in habitat.

A new Yale study in the journal Proceedings of the Royal Society B suggests that researchers exploring the factors behind these animals’ unusual size may need to go back to the drawing board.

“We do not find any correlation between the evolution of giant size in eurypterids and changes in habitat oxygen levels, temperature, latitude, or local diversity, all of which have been proposed as explanations for the evolution of giant size,” said Alex Ruebenstahl, a Ph.D. student in Earth & planetary sciences and the study’s co-first author with former Yale graduate student Nicolás Mongiardino Koch, who is now a postdoctoral researcher at the Scripps Institution of Oceanography in California.

For the study, the researchers analyzed 138 eurypterid species and assembled a dataset of sea surface temperature, levels of dissolved oxygen, and other data relating to ancient habitat. They found that the evolution of giant size in eurypterids was rapid, and in some instances giant species evolved amongst much smaller relatives. They also found that eurypterids evolved giant size at least nine times independently in different groups.

The eurypterids’ gigantism was not necessarily a response to environmental factors, the researchers said, noting that features of eurypterids themselves — such as their reproductive strategy or the size of their genome — may have allowed them to evolve giant size rapidly.

“Gigantism is an important feature of these remarkable fossil arthropods and ours is the first comprehensive analysis of the phenomenon in a phylogenetic context, i.e., considering their relationships and evolutionary history,” said Derek Briggs, the G. Evelyn Hutchinson Professor of Earth & Planetary Sciences in Yale’s Faculty of Arts and Sciences and senior author of the study.

The study was inspired, in part, by the Ciurca Collection in the Peabody’s Division of Invertebrate Paleontology — an extensive collection of sea scorpions donated by the late Samuel J. Ciurca Jr., a former curatorial affiliate of the Peabody.

The study was also co-authored by former Yale postdoc James Lamsdell, who is now an associate professor of geology at West Virginia University.

An age-old question

Members of the LGBTQI+ population experience less access to health care, worse health outcomes, and higher rates of uninsurance than their counterparts, research has shown. To expand coverage and address health care disparities affecting LGBTQI+ populations, some U.S. lawmakers have proposed lowering the Medicare eligibility age from 65 to 60. In a new study, Yale researchers evaluated whether this would have a meaningful impact on LGBTQI+ health equity.

Using data from the largest nationwide annual health survey — conducted between the years 2014 and 2021 — the researchers compared data from individuals who identified as heterosexual with data from those identifying as lesbian, gay, bisexual, or “other” (per the survey options). Nearly 928,000 individual respondents, ages 51 to 79, were included in the study, which was published in JAMA Health Forum.

The researchers found that aging into Medicare led to increases in health insurance coverage rates, access to health care, and health for all groups. But improvements in insurance coverage and health care access, respectively, were stronger for heterosexual individuals than for LGB+ respondents. Among LGB+ individuals, only self-reported health showed larger gains. However, when the researchers repeated the analysis on a subset of individuals in U.S. states with the greatest LGBTQI+ disparities, Medicare coverage benefited LGB+ individuals more than heterosexual respondents in coverage, access, and health status.

“This tells us that while Medicare access has positive effects, lowering the age of eligibility alone is likely not sufficient to overcome the structural and interpersonal forms of discrimination that affect LGBTQI+ populations nationally and may most benefit LGBTQI+ individuals living in states with the highest disparities,” said Kyle Gavulic, lead author of the study and an M.D.-Ph.D. student at Yale School of Medicine and Yale School of Public Health. “Additional interventions will be needed for larger, more widespread improvements to LGBTQI+ health equity.”

Delusions and the brain

Delusions — fixed false beliefs — can be tricky to study. And it’s not yet clear how the brain gives rise to these departures from reality. Further, there are many types of delusions. Those with persecutory delusions or paranoia, for example, believe others have harmful intentions toward them, while individuals with delusions of control believe others have command over their thoughts.

In a recent study published in the journal Brain, Yale researchers began to tease apart how brain processes contribute to different types of delusions.

For the study, volunteers with either paranoid or non-paranoid delusion-like beliefs performed two computer tasks. In one, the rules for winning changed over time, requiring participants to update their beliefs. The second task evaluated to what extent established information blocked participants’ learning of new information.

“Essentially the tasks were aimed at observing how people formed beliefs and how they changed them,” said Philip Corlett, an associate professor of psychiatry at Yale School of Medicine. “We found that people with delusion-like beliefs performed differently than healthy individuals. But we also found that people with paranoid and non-paranoid beliefs performed differently than each other, which hasn’t been observed before.”

The findings, says Corlett, suggest that learning dynamics have a significant role in how different types of delusions arise, which could inform how to predict risk of psychosis across individuals.

Ringing the bell for better green health care metrics

There is a growing movement to promote greener policies to achieve greater environmental sustainability at hospitals and other health care facilities. Yet without accurate, meaningful metrics to measure progress, advocates warn, such policies and practices are likely to be less effective.

In a new article in the journal The Lancet Planetary Health, Yale researcher Jodi Sherman and colleagues from Northeastern University and the Potsdam Institute for Climate Impact Research in Germany suggest four guiding principles for the next generation of health care sustainability metrics:

• Metrics should reflect the full scope of emissions caused by health care, both directly and indirectly.
• Metrics should reflect not just greenhouse gas emissions but also other environmental pressures and their potential health impact.
• Metrics should be linked to the core mission of health systems, from clinical outcomes of treatments reflecting quality performance of a health care organization, to overall population health.
• Metrics should recognize the wide diversity of health care, from large, well-resourced hospitals to “a mobile clinician with a medical bag.”

Sherman is an associate professor of anesthesiology at Yale School of Medicine and of epidemiology in environmental health sciences at Yale School of Public Health. She is co-leader of the Lancet Commission on Sustainable Healthcare and director of the Yale Program on Healthcare Environmental Sustainability.

The first author of the new article is Matthew Eckelman, associate professor at Northeastern who is also an adjunct associate professor at the Yale School of Public Health.

Getting clued in on forensic expert stress and decision-making

In 2004, forensic experts misidentified the perpetrator of a series of train bombings in Madrid, Spain, erroneously concluding that fingerprints collected from evidence matched those of a suspect who was later cleared. An investigation into the mistake found that fingerprint experts’ stress, among other human factors, played a role.

In a recent paper, Yale researchers assessed how stress might affect the performance of forensic experts and the quality of their decisions. Drawing from several fields (including cognitive psychology, medicine, and management), the researchers identified three factors that can affect forensic expert decision-making: the nature of the decision, such as the complexity of the evidence in question; individual differences, including the expert’s level of anxiety or tolerance of ambiguity; and the work environment. They then applied an evidence-informed structure for understanding workplace stress that breaks down its components and their effects.

“This framework can help stakeholders identify ways to manage stress at work and test how effective those approaches are,” said Mohammed Almazrouei, lead author of the paper and a postdoctoral fellow in the lab of Ifat Levy, a professor in the Department of Comparative Medicine at Yale School of Medicine.

The researchers suggest using terms like stress “management” or “optimization” rather than “reduction,” as the latter term suggests that workplace stressors should be uninformedly decreased. The paper emphasized that some types of stress can have positive effects on experts. Based on this work, the researchers identified short- and long-term interventions to address the detrimental effects of stress, including acknowledging occupational stress can affect experts’ decisions, providing trauma support, training managers in emotional intelligence, and instituting policies that do not punish employees who are forthcoming about their experience of stress.

“Ultimately, managing stress effectively can benefit forensic experts, forensic science organizations as a whole, and the administration of justice,” said Almazrouei.

Research Redux:

Distilling the facts behind a potentially revolutionary filtration process
Combined data speak volumes for prostate cancer treatment
Giant clams may hold the answer to making solar energy more efficient
New research findings could help rainforest restoration efforts
What shapes a virus’s pandemic potential? SARS-CoV-2 relatives yield clues