Rising infections from a dusty devil, and nailing down when our ancestors became meat eaters
Jan 16, 2025
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Meredith Wadman, a health and infectious disease writer, discusses the alarming rise of Valley Fever cases linked to climate change, drought, and wildfires. Her firsthand research in California's desert reveals the struggle to track this elusive fungus. Meanwhile, Tina Lüdecke, a group leader at the Max Planck Institute, dives into the diets of our ancient ancestors, using nitrogen isotopes to uncover when Australopithecus shifted to a meat-heavy diet, shedding light on how this transition may have shaped our evolution.
The rising cases of Valley fever in California and Arizona highlight the interplay of climate change, wildfires, and ecosystem dynamics in public health.
Investigating the diet of Australopithecus reveals their primarily plant-based nutrition, questioning the timeline and impact of meat consumption in early human evolution.
Deep dives
Rising Valley Fever Cases and Climate Connections
Valley fever, caused by the coccidioides fungus prevalent in hot, dry regions, is on the rise, notably in Arizona and California. Research suggests a connection between the increase in valley fever cases and factors such as drought, wildfires, and climate change, raising concerns about a potential spread throughout the western United States. A significant indicator of the increase is the rise in positive tests among dogs, particularly medium-sized breeds that dig into the soil where the fungus thrives. Data shows that counties reporting canine infections dramatically increased from 2.4% in 2012 to 12.4% in 2022, indicating a broader problem that parallels the increasing incidence of human cases, which nearly quadrupled in California and rose by 73% in Arizona over a recent decade.
Challenges in Diagnosing Valley Fever
Diagnosis of valley fever is complicated due to its similarity to more common respiratory infections, which often leads to a delay in appropriate treatment. Patients frequently experience pneumonia-like symptoms; however, about 60% of those infected may remain asymptomatic, complicating the understanding of its prevalence. On average, it takes about 38 days for patients from their initial medical visit to receive a definitive diagnosis, during which time the infection can progress, making timely diagnosis critical. The increase in hospital admissions following wildfire events underscores the urgent need for awareness and understanding of the disease as more people are at risk, even those who are otherwise healthy.
Insights into Early Hominins' Diets
Research focusing on the diet of ancient hominins, particularly Australopithecus, reveals that their consumption primarily consisted of low-protein, plant-based resources, with little evidence of significant meat consumption. By analyzing nitrogen isotopes in tooth enamel, scientists determined that these early ancestors had isotope ratios consistent with a vegetarian diet, indicating they did not rely heavily on meat for nutrition. However, the wide range of nitrogen values among individuals hints at some ecological variability in their diets, suggesting they may have engaged in behaviors such as termite fishing or consumed diverse plant materials. This research not only sheds light on the dietary habits of Australopithecus but also opens up questions about the evolution of diet through different hominin species and their interaction with varying environments over time.
First up this week, growing numbers of Valley fever cases, also known as coccidioidomycosis, has researchers looking into the disease-causing fungus. They’re exploring its links to everything from drought and wildfires to climate change and rodent populations. Staff Writer Meredith Wadman joins host Sarah Crespi to discuss her visit to a Valley fever research site in the desert near Bakersfield, California, where researchers are sampling air and soil for the elusive fungus.
Next up, scientists are trying to pin down when meat eating became a habit for human ancestors. It’s long been hypothesized that eating meat drove big changes in our family tree—such as bigger brains and more upright posture. Tina Lüdecke, a group leader at the Max Planck Institute for Chemistry and honorary research fellow at the Evolutionary Studies Institute at the University of the Witwatersrand, investigated the diet of our ancient hominin relativesAustralopithecus. Her team used nitrogen isotope ratios from the tooth enamel in seven Australopithecus individuals in South Africa to determine what predominated in their diets at the time—meat or veg.
This week’s episode was produced with help from Podigy.