Letters from the January 13, 2007, issue of Science News

Sunny exposition

“The Antibiotic Vitamin” (SN: 11/11/06, p. 312) reminds me that in preantibiotic days, tuberculosis patients were put on a fresh-air-and-sunshine regimen. Could the vitamin D so acquired account for the cures this system sometimes produced?

Nancy Axford
Sacramento, Calif.

Researcher John J. Cannell points to TB sanitariums as anecdotal evidence that sunlight fights infections.—J. Raloff

Does the vitamin D in milk help protect against infection?

Graeme McRae
Palmdale, Calif.

Probably not, according to Michael Holick of Boston University, who has measured the vitamin’s content in milk. Far better, he says, would be cod-liver oil, with “a whopping 1,360 [international units of vitamin D] per tablespoon.”—J. Raloff

Animal instincts

The idea of Pleistocene rewilding in North America is provocative (“Brave Old World,” SN: 11/11/06, p. 314), but it need not be treated only in the abstract. The return of beavers (Castor canadensis) to almost every region of the continent has shown us that the behavior of these creatures was, in many ways, originally responsible for the contours of the landscape and many rich soil deposits. Left to their own ways, beavers could reintroduce us to a North America that disappeared when they did.

James M. Bryant
Riverside, Calif.

The article presented an absolutely hair-raising scenario of potential ecological disaster. Introduction of plants or animals at a rate faster than can occur naturally causes a wave of parasitic inoculation that can rapidly devastate naïve local populations.

W. Geisler
Pelham Manor, N.Y.

The animals would have to be engineered to be inedible and to have instinctive knowledge of property and trespass law and an innate passion for strict compliance, or they would not survive. I would think that pigs with wings would be less challenging.

McClellan Blair
Indiana, Pa.

The magazine’s cover, with megafauna on one side of a fence and a highway on the other, perfectly illustrates a more pressing environmental problem: fragmentation of habitat.

Peter Wilson
Simi Valley, Calif.