Taking Earth's Temperature Hand-Me-Down Smoke "Smoke Gets in Your Hair" [R&D;, January] states that "Nonsmokers working in places that allowed unrestricted smoking exhibited nicotine levels nearly as high as those who were moderate smokers" and then goes on to suggest that secondhand-smoke exposure in a smoky workplace could pose the same health risks as moderate smoking. Since nicotine is addictive, then why don't nonsmokers in smoky workplaces become addicted to secondhand smoke?
Matthias Welchner—Ottawa, Ontario
Reporter Solana Pyne responds: Active and passive smokers absorb nicotine at different rates, sparking different physiological responses. Passive smokers generally don't become addicted to secondhand smoke because they take in the nicotine gradually. Smokers, on the other hand, get a drug spike to the brain with each drag off their cigarette. That stimulating yet relaxing rush is what makes smoking so addictive.
You Scratch My Back . . . "Why We Take Risks" [December] was an auspicious recapitulation of Zahavi's handicap principle. However, although this principle can be extended to explain many human and animal behaviors, to assert that it explains altruism is a specious claim. William Hamilton's theory of kin selection aptly explains any altruistic act between individuals that share genes. Reciprocal altruism justifies why we behave altruistically toward those unrelated to us. Author Richard Conniff uses philanthropic donations as an example of the handicap principle in action, but certainly Bill Gates's and Ted Turner's backs were reciprocally scratched after their generous donations. Employing Zahavian signaling to explain these behaviors is simply a case of old wine in new bottles.
Aaron Taylor Goetz—Austin, Texas
Richard Conniff responds: I agree that kinship selection can be an adequate explanation for altruism if donor and recipient are closely related. Reciprocal altruism is also a good explanation for altruism where there is a chance the recipient can repay the donor. But neither explanation really works, for instance, when the philanthropist is in the United States and the recipient is a complete stranger suffering from river blindness in Kenya. In such cases, altruism seems to be, as Zahavi suggests, a form of advertising.
Repeat Performance? I read with interest that the young chimpanzee Ayumu learned to "read" a lexigram that matched a colored square by observing the training of his mother, Ai ["The Year in Science," January]. It should be noted that Ayumu's performance was matched 17 years ago by Kanzi, a pygmy chimpanzee. Kanzi observed his stepmother, Matata, undergoing training on a similar task. Although Matata failed at the task, Kanzi learned to use lexigrams without any formal training. He amazed his trainers by pressing the lexigrams for "apple" and "chase," then picking up an apple and looking around with a play face to see whether the researcher, Dr. Sue Savage-Rumbaugh, would chase him.
William A. Hillix, Ph.D.—La Mesa, California
Fair Warning In "Ready to Rumble" [R&D;, November] there is an incorrect interpretation of our results. We are not suggesting that there is any immediate threat from the Yellowstone caldera. No volcano explodes without warning. Present-day monitoring systems allow short-term prediction of volcanic eruptions, and the U.S. Geological Survey and a number of other organizations conduct these observations at Yellowstone. Our results suggest only that Yellowstone will most likely erupt in the future, possibly within 100,000 years or several hundred thousand years, but definitely not tomorrow.
Dr. Ilya Bindeman—University of Wisconsin Madison, Wisconsin
Errata Contrary to our statement that atomic physicist Ugo Fano carried out the first controlled nuclear chain reaction in 1942 ("The Year in Science," January, page 79), this was accomplished by Enrico Fermi. Also, statistician Bjorn Lomborg, whose nationality we identified as Dutch in Reviews (January, page 81), is Danish.
