Kevin A. Strauss's otherwise excellent article, “Genomics for the People,” about the wonderful research and services being carried out for Amish and Mennonite families at the Clinic for Special Children in Strasburg, Pa., gives the impression that there is a genetic test that can “inform us about a child's risk for bipolar disorder 30 years hence.” Unfortunately, no such test exists. Bipolar disorder is associated with numerous genes and nongenetic risk factors. No single gene is necessary or sufficient.

Genetic research is important to understanding the origins of many mental illnesses. But tests that can make useful predictions are not yet on the horizon.

Chief, Human Genetics Branch, National Institute of Mental Health President, International Society of Psychiatric Genetics

STRAUSS REPLIES: McMahon, a leader in psychiatric genetics, makes a familiar claim about the multifactorial nature of mental illness and is correct to point out that no single genetic test can unequivocally predict a person's risk for bipolar disorder. Nevertheless, among the people we serve, a rare alteration in a gene called KCNH7 does appear to confer a major risk for this seemingly complex disease. We screened a total of 394 Amish research subjects for the KCNH7 mutation; 84 of these individuals carried at least one copy of the gene variant, and the lifetime incidence of bipolar spectrum disorders among them was 49 percent (41 people were affected with the disease). For comparison, the aggregate lifetime prevalence of bipolar spectrum disorders worldwide is about 2.4 percent. Thus, this single genetic test can indicate a risk for bipolar illness that is 20-fold higher than that of the general population. This is useful clinical information and suggests that Amish people with the mutation should be monitored carefully and offered intervention as soon as symptoms arise.


We were very disappointed in “Telescope Wars,” by Katie Worth. Contrary to the article's assertions, “bitter rivalries” from the past played a very small part in the history of the Thirty Meter Telescope (TMT) and Giant Magellan Telescope (GMT) projects. Why the Carnegie Institution for Science's repeated attempts to join the TMT project were rebuffed is a complicated story that only those at the California Institute of Technology and the University of California know completely, but it is clear that the internal dynamics of the partnership and the desire to control the technical development of the telescope played large roles. We at Carnegie eventually gave up when it became clear that we could never be more than a small, passive partner and when J. Roger Angel's development of the GMT concept provided a more attractive alternative.

Further, the article's claim that there are insufficient funds in the U.S. to support two such projects is faulty. Both the GMT and TMT are international collaborations, with about 80 percent of the TMT's funding coming from outside the U.S. and about 20 percent of the GMT's. In effect, U.S. resources are providing the funding for only one telescope. Three very large telescopes—the GMT, the TMT and the European Extremely Large Telescope—are the least that will be needed to enable the astronomical research of coming decades. There is no evidence, nor is it sensible to believe, that either the TMT or GMT would be much advanced if more money had been available; the technical challenges of very large telescopes are daunting, and these have set the pace.

Carnegie Observatories


Thank you for advocating for a carbon tax in “The Price of Pollution” [Science Agenda]. We at Carbon Washington, a grassroots organization of students, community members and economists, agree that a carbon tax is an economically feasible way to reduce air pollution caused by CO2-emitting fossil fuels.

Last December we submitted more than 360,000 signatures to Washington's secretary of state for our statewide, revenue-neutral carbon tax initiative, I-732, which would institute a tax of $25 per metric ton of CO2 on fossil fuels in the state. If I-732 succeeds at the polls, we hope that it can serve as a model for other states to implement their own carbon tax systems.

Carbon Washington

One benefit of a national carbon tax the article fails to mention is improved health. As a carbon price reduces coal, oil and gas use, fewer Americans will get sick.



In “Consilience and Consensus” [Skeptic], Michael Shermer's arguments demonstrate how deniers of anthropogenic global warming (AGW) are wrong. But he doesn't give reasons for why they deny AGW.

If we look for patterns among skeptics, a characteristic comes to light: they are extremely religious and conservative. At a fundamental level, they cannot accept that human beings have the power to destroy God's work. Senator James Inhofe of Oklahoma, for example, said: “The arrogance of people to think that we, human beings, would be able to change what [God] is doing in the climate is, to me, outrageous.”

El Puerto de Santa María, Spain

SHERMER REPLIES: Senator Inhofe's antics on the Senate floor are embarrassing to most thoughtful Christians. Fortunately, he and other conservative Christians are being challenged by climate scientist Katharine Hayhoe, who also happens to be an evangelical Christian on a crusade to demonstrate to her fellow believers why being a Christian is not in conflict with accepting climate change.

In my opinion, however, the denial of climate change is driven more by economic ideology than religious belief, primarily the fear that if climate change is real and voters decide that we ought to do something about it, that something might include the curtailment of polluting industries.


“The Heat Vacuum,” by Rachel Nuwer [World Changing Ideas], incorrectly refers to silicon dioxide atoms behaving like antennas. It should have referred to molecules of silicon dioxide. The article also says the material discussed radiates at wavelengths between eight and 13 nanometers; the correct measurement is eight to 13 microns.

“The Big Bang's Particle Glow,” by Shannon Hall [Advances], states that there are 10 billion particles of matter in the universe for every one antimatter particle. The universe does have many more particles of matter than antimatter, but the exact ratio is unknown.

Quick Hits [Advances] indicates that Australia's new curriculum for elementary school students will replace history and geography with computer coding. History and geography will still be taught, though within a new single humanities and social sciences subject.