What does a scientist in Easton, Pa., know about jackalopes – the mythical critters of the American West?

A lot, it turns out.

James Holliday, an emeritus professor of biology at Lafayette College, has a website devoted to jackalopes. The site is well-documented, with pictures and newspaper clippings referring to jackalopes throughout history.

When researching and reporting my stories about a bill before the Wyoming Legislature that would make the jackalope the state’s mythological critter, I came across Holliday’s website.

I had to talk to him.

Holliday told me the first time he saw a jackalope was at Wall Drug in South Dakota. It was made of fiberglass.

He became fascinated with the jackalope, not because of mythology or the legend but because of science.

What struck Holliday was “the idea that there might be a biological cause for the legend of the jackalope.”

Wait. A biological cause?

“There is a virus that causes growths on the jack rabbit,” Holliday said.

The virus is called Shope papillomavirus.

Growths can come out of rabbits’ bottoms and heads. When they grow from the head, they can look like horns.

Holliday described a rabbit that had a growth on its mouth.

“The poor thing starved to death,” he said.

Holliday’s jackalope website, which he runs with colleague Dan Japuntich, features photos of rabbits with Shope papillomavirus and even people with growths that look like horns.

Scientists believe the virus was in North America for centuries, but showed up in Europe shortly after Christopher Columbus returned from his voyage to the New World.

“The European rabbits got the virus and therefore the horns that it makes,” he said. “All of it struck me as interesting.”

Visit Holliday’s jackalope website, which in addition to biology has documents like Wyoming Gov. Ed Herschler’s 1985 declaration that made Douglas the “Home of the Jackalope.”

Reach state reporter Laura Hancock at 307-266-0581 or at laura.hancock@trib.com. Follow her on Twitter: @laurahancock.