Evolutionary biologists like to study rodent fossils. Rodents occur in high population numbers, and their rapid generational turnover means evolutionary change occurs faster than with larger slower breeding animals. Scientists recently studied pine vole teeth from 2 caves in Kentucky and 1 cave in Georgia that date to the last Ice Age and compared them with modern day pine vole teeth. Pine vole teeth from Hilltop and Cutoff Caves in Kentucky date to about 30,000 years ago, and the pine vole teeth from Yarbrough Cave in Georgia date to about 23,000 years ago. Pine voles are still a common species, occurring all across eastern North America. Despite their name, they prefer living in moist deciduous forests where they tunnel under tree roots and feed on roots, seeds, fruit, fungus, and insects. Their fossorial existence keeps them safe from owls and hawks, though snakes can enter their burrows. Pine voles are considered arvicolid rodents because their teeth cusps are in the shape of alternating triangles. Other common arvicolid rodents include meadow voles, lemmings, muskrats, and cotton rats.
Pine voles weigh just an ounce. They mostly live underground but occasionally venture to the surface.
Pine vole range. Pine vole is a misnomer. They prefer moist deciduous woods, not pine forests. Nobody knows why the common name is pine vole.
The pine vole teeth from the Kentucky Caves show the pine voles living then were the same size as modern day pine voles living in the region. However, pine voles living in north Georgia during the Ice Age were larger than modern day Georgia pine voles and about the same size as northern pine voles. Scientists believe this was in response to colder temperatures. Bergmann’s rule states that animals living in colder climates generally grow to a larger size because they are better able to retain body heat. The authors of this study can’t determine whether this large size was the result of inbreeding with northern populations of larger pine voles that colonized the region or natural selection of the local population.
Reference:
Martin, Robert; and K. O’Bryan
“Size and Shape Variation in the Late Pleistocene Pine Vole (Mammalia: Arvicolidae: Pitymys Pinetorum) First Lower Molars from 3 Caves in Kentucky and Georgia”
Paludicola September 2014
GeorgiaBeforePeople 
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