American Scientist

In this roundup, associate editor Nicholas Gerbis summarizes notable recent developments in scientific research, selected from reports compiled in the free electronic newsletter Sigma Xi SmartBrief: www​.smartbrief.com/sigmaxi/

Bricks, Frogs Beat Fungal Bug

Researchers have used common 10-hole masonry bricks, painted black, to provide warm shelters that strongly enhance the survival of endangered Australian frogs suffering from chytridiomycosis, a global disease that has eradicated 90 amphibian species and devastated hundreds more. In a lab and a controlled outdoor ecosystem, the green and golden bell frogs (Litoria aurea) overwhelmingly sought out the bricks as refuges. The snug hothouses raised the frogs’ body temperatures and helped them fight off the disease, which thrives in colder conditions. (Frogs, being ectothermic—or, less accurately, “cold-blooded”—rely on external sources to regulate their body heat.) Once recovered, the frogs retained a greater chytrid disease resistance, which could enable them to live longer, spread farther, and breed more successfully. Finding basic, cheap, and feasible strategies that let amphibians coexist with pathogens is vital to conservation and restoration efforts, because chytridiomycosis, which is chiefly caused by a water-dwelling fungus (Batrachochytrium dendrobatidis), tends to take up permanent residence in an ecosystem. The team, led by researchers from Macquarie University in Sydney, Australia, hopes the approach will help stem biodiversity threats to amphibians and help other animals affected by cool-weather fungal pathogens, such as snake fungal disease.

Waddle, A.W., et al. 2024. Hotspot shelters stimulate frog resistance to chytridiomycosis. Nature 631:344–349.

Reading the Neuron Lexicon

In a first, a team led by researchers at Harvard Medical School has mapped specific word meanings to particular brain cells and patterns. Their findings show how single-neuron recordings can add precise details and timing to neuroscience’s broader picture of hierarchical language processing. Patients who were already scheduled for related neurosurgeries were presented with words in various frameworks—from contextual stories to jumbled phrases and from nonsense words to homophones—while researchers used tungsten electrodes and silicon probes to record cellular activity in the left language-dominant prefrontal cortex, a part of the brain that is vital to speech and language comprehension. The neurons exhibited robust links to word meanings and categories, reliably distinguished nonsense words, and discerned differing meanings among same-sounding words via context cues. This finding suggests that comprehension is a dynamic and not “hard-coded” process. The work dealt solely with speech in right-handed English speakers. The authors hope to apply their methodology to multilingual patients and to other language modalities, such as pictures, videos, and nonspeech sounds.

Jamali, M., et al. 2024. Semantic encoding during language comprehension at single-cell resolution. Nature. Published online doi:10.1038/s41586-024-07643-2.

How Jupiter Changed Its Spot

Jupiter’s Great Red Spot might not be as old or as stable as was once thought, according to the latest entry in the long-running debate over the vortex’s origins. Based on past observations and drawings, three numerical models of the spot’s formation, and a simulation of its evolution, a Spanish team led by Agustín Sánchez-Lavega of the University of the Basque Country finds the biggest and most persistent storm in the Solar System differs from the “Permanent Spot” reported in 1665 by astronomer Giovanni Domenico Cassini: The size, motion, and patterns of the current storm mean that Cassini’s spot, which was last observed around 118 years before the first Great Red Spot reports, was an earlier storm that shrank and disappeared. The models suggest the current spot arose later due to strong changes in the speeds of nearby Jupiter-circling winds, combined with a south tropical disturbance (a flow of gases from another band that impedes east–west circulation, see image below). Since then, the modern spot has shrunk and sped up its rotation. Together, the data offer vital insights into the weather dynamics of gas giants.

Sánchez-Lavega, A., E. García-Melendo, J. Legarreta, A. Miró, M. Soria, and K. Ahrens-Velásquez. 2024. The origin of Jupiter’s Great Red Spot. Geophysical Research Letters 51:e2024GL108993.

Rethinking Cahokia’s Decline

Ancient soils unearthed at Cahokia Mounds near St. Louis suggest that the largest precontact Indigenous settlement in North America, home to tens of thousands, did not die out due to a regional multidecade drought. Past analyses have tied the rise and fall of the political and religious center of the Mississippian Cultural Tradition (1050–1600 [all dates approximate]) to the unusually warm period called the Medieval Climate Anomaly (900–1250) and to the Little Ice Age (1250–1830), respectively, arguing that drought caused an ecological transition to prairies, lowering maize yields and driving down the population. But, by examining organic remains in Cahokian soils in conjunction with carbon-12 and carbon-13 analysis (differing ratios of which indicate dry- versus wet-adapted plants), Caitlin Rankin of the Bureau of Land Management and Natalie Mueller of Washington University in St. Louis established that no such prairie transition or widespread crop failure took place, which could mean that social change and warfare played a greater destructive role than was once thought. The findings underline the value of looking past regional climate events to grasp local effects, both in archaeology and in climate change research.

Rankin, C. G., and N. G. Mueller. 2024. Correlating Late-Holocene climate change and population dynamics at Cahokia Mounds (American Bottom, USA). The Holocene. Published online doi:10.1177/09596836241254488.