Charles Darwin told us that in nature, the strong survive and the weak perish. Darwin is long gone, but his theory lives on.

Check out Geri Nikolai’s story in the Rockford Register Star “You’re not nuts, they’re black squirrels.”

Black squirrels (great name for a band, in my opinion) have been showing up frequently in theblacksquirrel.jpg Rock River Valley, according the paper, which informally polled 250 News Tower employees. The story said:

“We got about 20 responses, with sightings from near downtown to South Beloit. Good places to spot them, we were told, are Shorewood Park in Loves Park; the Pepper Drive/Mulford Road area; and Harlem Road in the Perryville/McFarland region. One man said he’s seen them around for at least five years.”

Experts says aside from color, black squirrels are the same as gray squirrels. But their origin, in some regions anyway, may be alien.

In Washington, D.C., researchers have traced the region’s population of squirrels to 18 Canadian black squirrels that were released more than 100 years ago (“An Exotic Evolution: Black Squirrels Imported in Early 1900s Gain Foothold,” Washington Post).

The Post says:

“Scientists say it’s a real-life example of natural selection at work, which has rolled on for a century here without much public notice.

“It shows the spread of a gene within a population,” said Richard W. Thorington Jr., a Smithsonian Institution researcher working on a book that includes a history of the District’s black squirrels. “That is evolutionary change before your eyes.”

And further:

Here’s why some scientists believe the black squirrels were multiplying: In winter, their dark coats allowed them to retain heat from sunlight, leaving them less desperate for warmth than their lighter-colored cousins.

“If you can do it with solar heat, you don’t need quite as much metabolic heat,” and, therefore, need less food, Thorington said.

Squirrels in general have adapted well to human development. And as cities and towns sprawl into the countryside, it may be that more people are seeing black squirrels because they’re living where the squirrels have always been.

And the gene for black fur, which may have been isolated in a pocket of squirrels in a woods, has ridden a squirrel population explosion brought on by human development into greater genetic prominence.

At least that’s what Darwin might say.