Web edition: August 21, 2007
Print edition: August 25, 2007; Vol.172 #8 (p. 127)

Where did the chicken cross?

"Chicken of the Sea: Poultry may have reached Americas via Polynesia," (SN: 6/9/07, p. 356) states, "The most likely sea route ran north of Hawaii and down America's Pacific coast." The Polynesians were master mariners, so anything is possible, but continuing east from Tonga to South America is an extension of the main voyaging area, whereas Hawaii is well off this beaten path.

Tom Mallard
Phoenix, Ariz.

A guy thing

"Brain Gain: Constant sprouting of neurons attracts scientists, drugmakers" (SN: 6/16/07, p. 376) states, "Exercise, estrogen, [and more examples] all rev up production of new brain cells." I am compelled to ask: If estrogen leads to neurogenesis, does the "male" hormone testosterone also?

Jaime Hunter
Mesquite, Texas

There's good evidence that testosterone increases neurogenesis in songbirds but little evidence that it does the same in mammals.—B. Vastag

First line of defense

In "Moths mimic 'Don't eat me' sounds" (SN: 6/23/07, p. 397), the study is reported as the "first confirmed acoustic example of classic defensive mimicry." Not so. In 1986, Matthew P. Rowe and colleagues published in Ethology an elegant study demonstrating that the burrowing owl's hiss is acoustic defensive mimicry of the rattlesnake's rattle.

William K. Hayes
Loma Linda University
Loma Linda, Calif.

Death defining

In "Jurassic CSI: Fossils indicate central nervous system damage" (SN: 6/23/07, p. 390), the unusual head positions seem to indicate that these creatures died from a kind of nerve damage. One of the possibilities is oxygen deprivation. Doesn't this suggest that most of these creatures probably died from suffocation after a sudden mud slide or other deluge?

Ron McMurtry
Modesto, Calif.

Suffocation from a mud slide, deluge, or volcanic eruption is a strong possibility. But not all fossils in this pose are found in those geological settings.—C. Barry