Yawn and open your ears
I read with interest your article on yawning (“Yawn,” SN: 5/7/11, p. 28). Over the years I have formulated a private theory on at least one of the reasons why we yawn and would like to share my speculations with your readership.

My insight essentially began when I noticed that immediately after yawning my hearing acuity noticeably improved (sometimes dramatically so) for at least a short period of time. I have observed this phenomenon in myself on multiple occasions over my life span from adolescence to my current age of 67 years.

I believe the process of yawning opens the eustachian tubes which equalizes the pressure in the middle ear which, in turn, allows for improved sound conduction through the ossicles into the inner ear. This pressure adjustment should also affect the back pressure on the membrane of the round window to improve the fine tuning of the cochlear hair cells’ response.

Whatever the details of the mechanism, a case can easily be made that improved hearing is an advantage for both predator and prey that would be differentially favored by natural selection. As to why yawning should be contagious and why it should tend to occur when one is drowsy or bored: If group members are signaling to each other unconsciously through their yawns to awaken and prick up their ears, this could confer a survival advantage not only to the group as a whole, but to each individual and thus to their “selfish genes.”
Robert Gorkin, via e-mail

Other causes of yawning: Reading about it. I had at least 22 while reading that article.
Louise Lacey, Kensington, Calif.

Pondering poison origins
I wonder if it was not the caterpillars that gave the cyanide-producing genes to the bird’s-foot trefoil plant (“Prey, predator make same poison,” SN: 5/7/11, p. 11). Look how clever this would be: First, the caterpillar does not expend energy to make cyanide, and second, no other organism can eat the trefoil! No more competition with other creatures consuming its food.
E.G. Howard, Hockessin, Del.

Rutherford tribute
I have enjoyed my subscription to Science News for years and give a subscription to my son for his birthday present each year. (He returns the gesture by giving me one to Rolling Stone magazine.) In your May 7 issue, Tom Siegfried did an article about Ernest Rutherford (“Atomic anatomy,” SN: 5/7/11, p. 30). I enjoyed reading about Mr. Rutherford and his contributions to the nuclear age.

I would like to see more articles like this, on other scientists, in each issue to inform readers about history and the people who have contributed to our understanding of the sciences.
Don Hansen, via e-mail

I enjoyed the Rutherford piece. Maybe someday Tom Siegfried can write about (if he has not already) the incomparable Michael Faraday. The older we get, the more we like to know about the people who got us where we are.
John E. Rhoads, Wichita Falls, Texas

Traveling salesman solved, slowly
Well, send me the million dollars. The article “Cells can chart efficient course from A to Z” (SN: 5/7/11, p. 14) states, “Scientists still don’t have one clean algorithm that can crunch the numbers, no matter how many cities, and find the shortest route.” Replacing the expression “clean” with “efficient” would, alas, prevent me from cashing that check. Any casual programmer can write a “clean” algorithm to address the traveling salesman problem — it simply won’t finish running before the sun goes dark.

Incidentally, my clean (but inefficient) algorithm requires factorial time, not exponential time. I’m pretty sure that bringing it down to merely exponential time would win me that million dollars in prize money.
Joseph C. Nemeth, Fort Collins, Colo.

Exceptional dinos
Alexandra Witze’s feature “Dawn of the dinosaurs” (SN: 5/21/11, p. 22) was a fun read, about something that I hadn’t seen addressed before. I have one question regarding the proposed extinction at the end of the Triassic period.

Why were dinos hit less hard than non-dinos?
William Check, via e-mail

No one knows. — Alexandra Witze

I’ve been a subscriber for over 40 years, and I found the “Stellar oddballs” article (SN: 6/4/11, p. 18) to be the most interesting and exciting Science News article I’ve ever read! Well done!
Duane Morse, Phoenix, Ariz.

The caption in the graphic accompanying the news story “Natural catastrophe begets nuclear crisis” (SN: 4/9/11, p. 6) should have said that the nuclear reactor design uses water to moderate (not absorb) neutrons.

An article in the June 4 issue (“Stellar oddballs,” SN: 6/4/11, p. 18) incorrectly reported that the Kepler spacecraft would operate for four or five years longer. It should have said that the craft might operate four or five years beyond its normal mission timeline, which ends in 2013.

The table on Page 23 of the article “Healthy aging in a pill” (SN: 6/4/11, p. 22) misstated the effect of caloric restriction on mouse life span. It should have said that mice on a calorie-restricted diet live 30 to 50 percent longer than normal.