Connecting the lincs As a physician, I was absolutely astounded reading “Missing lincs” (SN: 12/17/11, p. 22) and still am. We have been waiting since DNA was discovered to find this ‘what makes us human’ aspect of our biochemistry. Even in the infancy of this research, we are discovering the chemical reasons for a type of muscular dystrophy and other conditions. What I find especially illuminating is that this may be the etiology of what we call autoimmune diseases, among other problems. I am sure we will find it is a change in lincRNA balance or function that produces the change ... (p. 31)

Finding parasitic behavior Two adjacent stories, both by Tina Hesman Saey, at first glance may appear to be unrelated but in actuality show examples of a well-known phenomenon: parasites adversely affecting the behavior of the host so that the parasite can get to its next victim. The article “Belly bacteria can boss the brain” (SN: 10/8/11, p. 9) is an example of such behavior. A stressed-out wild mouse that clings to walls and avoids swimming is a mouse that lives to breed another day. Being relaxed is no more beneficial to it than climbing to the top of the tree is for the caterpilla... (p. 31)

The eyes have it Just finished the latest issue of your spectacular magazine. I’ve been a reader for many years, but this is the first time I’ve felt compelled to write in. In the article about the tadpole (“Tiny voltage grows eyes in strange places,” SN: 12/31/11, p. 5), the final sentence is a quote from Coffman: “The fact that a narrow range of voltage is enough to specify an eye is kind of amazing.” What might be even more amazing is if researchers find out the voltage level that prompts cells to initiate and grow malignant tumors. I hope someone will help me stir up some i... (p. 31)

Skaters slide Regarding the article “Skateboarders rock at physics” (SN: 12/3/11, p. 10), the skateboarders’ “intuitive” conclusion that the ball will roll faster down the blue ramp (which is longer but has two steeper sections compared with the shorter red ramp with a single shallower section) depends on the particular geometries chosen for the two ramps. I’ve programmed the solution for a point particle sliding (so no rolling) without friction down the two ramps and find that for certain ratios of the heights and lengths of the various ramps, it can actually be faster to slid... (p. 31)

Thinking probabilistically In the excellent article “Beware the long tail” (SN: 11/5/11, p. 22), the areas under each curve in the figure “Spotting the tail” should be unity (the total probability must be one). Therefore, the red curve should be lower in the center than the black one. Filson Glanz, Durham, N.H. Yes, the area under each curve should add up to one. In this case the graphic was shown without a y-axis to illustrate the basic point about the shapes of such curves; it would have been more appropriate to have shown the curves separately rather than superimposed. —Ra... (p. 35)

Predators inspire poetry and fear Regarding “Lopped off” (SN: 11/5/11, p. 26): One of the Tao Te Ching’s chapters (excerpt below) is very prescient on the unintended consequences of human behavior. It was written around 500 B.C., long before our innovative abilities threatened the entire planet. It is ironic that science both leads to innovations that cause the destruction, and now allows us to realize the full range of consequences. Woe to him who willfully innovates While ignorant of the constant, But should one act from knowledge of the constant One’s action will lead t... (p. 30)

Clocking neutrinos In response to “Hints of a flaw in special relativity” (SN: 10/22/11, p. 18): When supernova 1987a was detected in the Large Magellenic Cloud (a distance of roughly 168,000 light-years) an influx of neutrinos was detected simultaneously (or nearly so) in Japan, the United States and Russia. Had these neutrinos traveled at the same speed (about 25 parts per million faster than light) as the CERN neutrinos detected by the OPERA experiment in Italy, they would have arrived roughly four years ahead of the visual display from 1987a, rather than at approximately the same ti... (p. 30)

Defining the human species Having read “Humans benefited by interbreeding” (SN: 10/8/11, p. 13), I wonder if I have missed what, to me, seems a major change in the definition of “species.” I was taught that the attempted crossbreeding of animals of two different species could result in either no offspring or sterile offspring. If modern humans carry genetic information from Neandertal and Denisovan ancestors, stemming from successful interbreeding that resulted in fertile offspring, why aren’t the Neandertals and Denisovans considered to be merely of a different race or bre... (p. 31)

Bull’s-eye targeted On the picture in “Galactic bull’s-eye” (SN: 9/24/11, p. 10), I am quite puzzled. Do my eyes deceive me, or is there another bull’s-eye galaxy behind the first, located at the 1 o’clock position? How is this possible? Are these strange objects magically clustered along some line pointing towards us? Jeff Brewer, Newton Centre, Mass. It is peculiar that another ring-galaxy–like object would appear in the background, and in fact the Hubble Heritage Team noted its odd appearance. It’s possible, but not probable, that the object is another Hoag... (p. 31)

Lumpy lunar illusion Are you folks aware of a phenomenon based on the universal expectation that objects are illuminated by light coming from above? Several startling optical illusions are based on this quirk of the mind. For example, the sharp moon map in “Orbiter delivers sharp moon map” (SN: 7/30/11, p. 12) makes the moon look like it is covered with big bumps! Turn the page upside down, and voila — the bumps turn into craters. Jeff Brewer, Newton, Mass. Count on crows to know Regarding “When birds go to town” (SN: 8/27/11, p. 26), I have observed other corvids... (p. 31)