Readers Respond to Rise of the Tyrannosaurs

VACCINATION STRATEGY

In “” [Science Agenda], the editors suggest that rather than “strong-arm tactics,” we should use a more subtle social strategy of “little nudges” to convince parents to vaccinate their children. But strong-arm tactics are nothing new to public health. How is a law that mandates vaccinations for school-age children, such as the one recently passed in California, any different from, say, fluoridating drinking water? Although forming peer-advocacy groups and promoting provaccine interactions with providers are part of the solution, I do not think these strategies alone are aggressive enough for a time-sensitive and life-threatening public health issue. California's law is a necessary measure to shift the immunization rate above the safety threshold.

HANNAH PECKLER

DINOSAUR EXTINCTION

Stephen Brusatte refers to the extinction of the dinosaurs in “.” What was so vulnerable in the dinosaurs that ensured their extinction while allowing mammals to survive and thrive?

PETER STEPHEN

Velociraptor .

RELATIVISTIC VOYAGE

In “,” Rolf Ent, Thomas Ullrich and Raju Venugopalan state that “physicists think that when protons and neutrons reach extreme speeds, the gluons inside the protons split into pairs of new gluons.”

But that would violate special relativity's tenet that the laws of physics are the same for all observers. Consider the perspective of a tiny physicist riding a proton in a vacuum, surrounded by a tube that races by at ever faster speeds. Our little physicist monitors his proton from time to time and always finds it the same. Which physicist's gluons are splitting—the tiny one or one observing from outside the tube?

CHARLES M. BAGLEY, JR.

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PUBERTY ONSET

After reading “,” by Dina Fine Maron [The Science of Health], I was surprised that there was not a mention of the impact of growth hormones in milk production. Can these hormones bear some of the responsibility for the early onset of puberty in girls?

VIVIAN FABBRO KEENAN

Although it is clear that obesity is part of the picture—fat cells secrete estrogen, which is the major hormone involved in puberty in girls—I was astounded that Maron ignored what is most certainly the cause of both obesity and early-onset puberty: a diet rich in high-fat animal products, including dairy foods, which are themselves rich in estrogen.

ADAM DAVE

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CELLULAR COMMUNICATION

My daughter and I were fascinated by the gap junctions—structures connecting cells to one another—described by Dale W. Laird, Paul D. Lampe and Ross G. Johnson in “.” Does cell communication via gap junctions occur with blood cells that are circulating through the body? And what about unicellular organisms, especially those that colonize?

JAMES WURZER

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Volvox Hydra .

CLARIFICATION

“,” by John Pavlus, refers to Moore's law as indicating that halving transistor size doubles computing performance. It should have referred to doubling the number of transistors on a chip to increase performance.

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