US EditionMost Rodents Have Ancient Thumbnails, Science Study Finds
Researchers found that 86% of rodent genera have thumbnails that enhance dexterity for breaking nuts, a trait linked to their evolutionary success and species diversification.
- Researchers published a study in the Sept. 4 issue of Science showing that most rodents have flat thumbnails on their first digit and curved claws elsewhere.
- The study examined 433 rodent genera from museum collections because earlier research suggested thumbnails evolved millions of years ago and vary widely.
- The researchers discovered that between 86% and almost 90% of rodent genera include species possessing thumbnails, which are believed to enhance their ability to grasp and break open energy-rich nuts.
- Coauthor Anderson Feijó suggested that the presence of thumbnails could be a key factor in rodents' evolutionary success, while Rafaela Missagia emphasized that their ability to efficiently grasp and manipulate food has contributed to their widespread expansion across the globe.
- This research highlights the value of museum collections and suggests that rodents' thumbnails helped them exploit nuts with less competition, leading to broad diversification.
13 Articles
13 Articles
Most rodents have thumbnails like us
The thumbnail and hand of a kangaroo rat, an example of a rodent with thumbnails that uses its hands to manipulate its food. Credit: Missagia et al 2025 A deep dive into the world of rodent thumbs could help explain why the creatures spread and thrived all over the world. The research examined hundreds of rodents in museum collections to track the evolution of their thumbnails. Many rodents have evolved smooth, flat nails rather than curved cla…
Evolution: In all mammals, the hand is a very important part of life. But rodent thumbs were long considered useless. Wrongly so. The…
Rodents’ secret weapon? Thumbnails.
While humans are Earth’s most dominant animal species, it’s really a rodent’s world and we are just living in it. Roughly half of all the mammal species on the planet are rodents such as rats, mice, squirrels, and hamsters and they are found on every single continent except for Antarctica. Their rapid reproductive rates, flexible bodies, diverse diets, and more have made them the ultimate survivors. Some of their success may also be due to a fai…
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