Why Rodents With Thumbnails Instead of Claws Dominate the World: Uncovering the Secret to Their Success

Imagine a squirrel deftly munching on an acorn. It holds the nut with its front paws, thanks to its unique thumbs. Instead of sharp claws, this little creature has smooth, flat nails that help it eat.

For years, scientists took notice of this oddity in squirrels and other rodents but hadn’t thoroughly studied the entire rodent family tree to see who has thumbnails and who doesn’t. Recently, researchers published a paper in Science that explores this very topic by examining hundreds of rodents in museum collections.

Rafaela Missagia, a researcher at the Field Museum in Chicago and an assistant professor at the University of São Paulo, shared, “When I mention that some rodents have thumbnails, most people are shocked. I was surprised too after years of studying them.”

The Field Museum boasts one of the largest mammal collections in the world. Rodents alone account for around 40% of all known mammal species, providing a wealth of material for research. Gordon Shepherd, a professor of neuroscience at Northwestern University, took an interest in Missagia’s findings and expanded on them using the museum’s collections.

Before diving into their research, the team knew some rodents sported claws, some had thumbnails, and others had neither. Shepherd noted, “Rodents with thumbnails tend to use them to hold their food.”

By examining the preserved skins of 433 rodent genera, the team discovered a striking 86% had thumbnails. They cross-referenced this data with the rodents’ eating habits, revealing an interesting link: rodents like guinea pigs, who lack thumbs, do not use their front limbs for eating. This research created a clearer picture of the rodent family tree, suggesting that all modern rodents descend from ancestors who sported thumbnails. This feature might even explain how rodents became such a dominant group worldwide.

The researchers believe that the flat thumbs offer better dexterity compared to long claws. This dexterity could be crucial for opening up high-energy food sources like nuts, which other animals struggle to access.

Not only do rodent nails indicate how they manage food, but they may also reflect their habitats. Missagia elaborated, “Rodents with nails tend to live above ground or in trees, while digging rodents often have claws.” This raises fascinating questions about how specific physical traits can determine an animal’s lifestyle and environment.

Interestingly, humans and primates also evolved nails instead of claws, although these adaptations occurred independently in a process known as convergent evolution.

This study emphasizes the importance of museum collections. As Feijó pointed out, “They are a treasure trove for new discoveries. Who would ever think that rodent thumbnails could lead to such insights?”

Rodents dominate the mammal population, with species found on every continent except Antarctica. Their unique traits, like thumbnails, help explain their evolutionary success and adaptability. As they continue to thrive, we can explore more about how small changes, like the shape of their thumbs, can lead to big impacts on survival and diversity.

Source link

Science, Physics News, Science news, Technology News, Physics, Materials, Nanotech, Technology, Science