Hear ye, hear ye

Heard this one before? Modern mammals are gifted with delicate eardrums that allow us to hear many frequencies and volumes. This gives us a leg up—or, perhaps, an ear up—on animals such as snakes that hear through bone conduction, a less sensitive method that relies on the movement of sound waves through skull bones. Researchers have long wondered when, exactly, mammals’ sophisticated hearing emerged. According to new research led by Alec Wilken, SM’26, PhD’26, and published in the Proceedings of the National Academy of Sciences in December, the answer is about 250 million years ago. The team discovered that an Early Triassic mammal ancestor called Thrinaxodon liorhinus had a primitive eardrum that allowed it to hear airborne sound. Using an engineering software tool typically used to predict stresses on physical structures such as bridges, the researchers modeled Thrinaxodon’s hearing process. They discovered that much of its hearing likely took place with the help of an eardrum—putting the emergence of this crucial evolutionary adaptation about 50 million years earlier than previously thought.—S. A.

Tiny particle, big results

Type 1 diabetes is caused by the immune system attacking insulin-producing cells in the pancreas. New research by postdoctoral scholar Jacob Enriquez and Professor of Medicine Raghu G. Mirmira, AB’86, PhD’91, MD’93, aims to treat the disease by giving insulin-producing cells, called beta cells, a way to keep themselves safe. The study was published in Cell Reports Medicine in February. The team developed lipid nanoparticles that give beta cells instructions to make more PD-L1, a protein that helps the beta cells evade the immune system. (The instructions are delivered through messenger RNA—the same approach used in the two primary COVID-19 vaccines.) The researchers found that the nanoparticles successfully reached the target beta cells and triggered PD-L1 production in both mouse and human cells. The team plans to continue studying how nanoparticles made of lipids can be used to deliver therapeutic molecules.—S. A.

Climate costs

The economic costs of natural disasters could rise sharply in the United States in the coming years, according to a new study published in December in Geophysical Research Letters. B. B. Cael, an assistant professor of geophysical sciences, analyzed more than four decades of data from the National Oceanic and Atmospheric Administration’s database of billion-dollar weather and climate disasters in the United States. According to his analysis, the financial cost of severe storms and other natural disasters, such as hurricanes, floods, and wildfires, increased from 1980 to 2024. The rising cost stemmed either from heightened exposure (the cost of the assets at risk increased) or from increased vulnerability (the assets became more susceptible to damage from weather and climate events). Through statistical analysis of these trends, Cael predicts a greater than 90 percent chance that total disaster damages between 2026 and 2030 will exceed $500 billion, and a 54 percent chance they will exceed $1 trillion. The study suggests the importance of investing in resiliency and preparedness.—C. C.