Letters from the February 3, 2007, issue of Science News

All together now

It is not only the scientific literature that documents the unexpected “doughnut” pattern in swarms (“The Mind of the Swarm,” SN: 11/25/06, p. 347). Italo Calvino’s fictional Mr. Palomar observed (rather more lyrically) about the flocking of Roman starlings, “Finally a form emerges from the confused flutter of wings, advances, condenses: it is a circular shape, like a sphere, a bubble, the balloon-speech of someone who is thinking of a sky full of birds … ” (Mr. Palomar, 1985, Harcourt Brace).

J. Pound
Worcester, Mass.

The article argues that reaching a consensus for movement is more complicated in humans than in animals, requiring “fancy cognitive skills.” However, in an airport or on a busy sidewalk, simple rules linked to crowd density and speed of walking may emerge to influence behavior in a rather mindless way.

Tim Schallert
Austin, Texas

Since it is a hallmark of most humans not to stick out from their crowd, a surprisingly large number of behaviors and thought processes in people are defined no differently than they are in the fish school. This includes religion, music and movie taste, fashion, and choosing to love or hate some group or individual.

Barry P. Skeist
Waverly, N.Y.

Inside story

Your article “Cancer Link: Gene regulates progesterone effect on breast cells” (SN: 12/2/06, p. 355) made a common mistake in characterizing the mechanism of steroid-hormone receptors. These receptors are not “proteins on the cell surface” but rather, and uniquely, positioned intracellularly. Steroid hormones pass directly from the bloodstream to the cytoplasm, where they induce changes in the receptor proteins, enable movement into the nucleus, and activate specific genes.

Mac Black
Seattle, Wash.>

Big is bountiful

Regarding “Stone Age Role Revolution: Modern humans may have divided labor to conquer” (SN: 12/2/06, p. 358), economists would suggest that population growth allowed the division of labor. Notice that the most advanced economies are those with the largest populations, allowing for specialization in production. As Adam Smith wrote in 1776, “The division of labor is determined by the extent of the market.”

Jim Klein
San Francisco, Calif.