In a letter in Thursday’s New England Journal of Medicine, three scientists from the Fox Chase Cancer Center in Philadelphia cite several dozen studies requiring a participant to be “in a reciprocal relationship with a person of the opposite sex.”

There are legitimate scientific reasons for excluding gays from certain studies. Scientists would want only heterosexuals if they were studying how HIV spreads during male-female sex, for example.

But the Fox Chase folks found cases where the reason for excluding gays is not clear: tests of a drug for attention-deficit disorder, a treatment for erection problems after prostate cancer surgery, and studies on sexual function related to diabetes, depression and benign enlargement of the prostate as men age.

Brian Egleston, a biostatistician at Fox Chase, made the observation while overseeing enrollment of patients into clinical trials at the cancer center.

“When I first saw this, I thought it was a fluke. The second time, I thought I’d dig deeper,” he said.

Egleston and Roland Dunbrack Jr., a biologist, and Dr. Michael J. Hall, a medical oncologist, did a spot check of a government database of thousands of studies and turned up more examples, most of them private-industry trials.

Researchers seeking federal money for their work must explain why a study excludes a group based on gender, race or ethnicity, but no explanation is needed for exclusion based on sexual orientation, Egleston said.

Exclusion can become self-perpetuating: Researchers designing a study often “cut and paste” participation criteria from earlier trials on a similar subject.

“It becomes the way it’s done,” and any bias gets repeated, Egleston said.

Estimates of how much of the U.S. population is gay or bisexual vary widely; some polls have put it around 4 percent.

The World Health Organization and the U.N. agency UNAIDS said the results “instilled new hope” in the field of HIV vaccine research.

The vaccine – a combination of two previously unsuccessful vaccines – cut the risk of becoming infected with HIV by more than 31 percent in the world’s largest AIDS vaccine trial of more than 16,000 volunteers in Thailand, researchers announced Thursday in Bangkok.

Even though the benefit is modest, “it’s the first evidence that we could have a safe and effective preventive vaccine,” Col. Jerome Kim told The Associated Press. He helped lead the study for the U.S. Army, which sponsored it with the National Institute of Allergy and Infectious Diseases.

The institute’s director, Dr. Anthony Fauci, warned that this is “not the end of the road,” but said he was surprised and very pleased by the outcome.

“It gives me cautious optimism about the possibility of improving this result” and developing a more effective AIDS vaccine, Fauci said. “This is something that we can do.”

The Thailand Ministry of Public Health conducted the study, which used strains of HIV common in Thailand. Whether such a vaccine would work against other strains in the U.S., Africa or elsewhere in the world is unknown, scientists stressed.

Even a marginally helpful vaccine could have a big impact. Every day, 7,500 people worldwide are newly infected with HIV; 2 million died of AIDS in 2007, UNAIDS estimates.

“Today marks a historic milestone,” said Mitchell Warren, executive director of the AIDS Vaccine Advocacy Coalition, an international group that has worked toward developing a vaccine.

“It will take time and resources to fully analyze and understand the data, but there is little doubt that this finding will energize and redirect the AIDS vaccine field,” he said in a statement.

The study tested the two-vaccine combination in a “prime-boost” approach, in which the first one primes the immune system to attack HIV and the second one strengthens the response.

They are ALVAC, from Sanofi Pasteur, the vaccine division of French drugmaker Sanofi-Aventis; and AIDSVAX, originally developed by VaxGen Inc. and now held by Global Solutions for Infectious Diseases, a nonprofit founded by some former VaxGen employees.

ALVAC uses canarypox, a bird virus altered so it can’t cause human disease, to ferry synthetic versions of three HIV genes into the body. AIDSVAX contains a genetically engineered version of a protein on HIV’s surface. The vaccines are not made from whole virus – dead or alive – and cannot cause HIV.

Neither vaccine in the study prevented HIV infection when tested individually in earlier trials, and dozens of scientists had called the new one futile when it began in 2003.

“I really didn’t have high hopes at all that we would see a positive result,” Fauci confessed.

The results proved the skeptics wrong.

“The combination is stronger than each of the individual members,” said the Army’s Kim, a physician who manages the Army’s HIV vaccine program.

The study tested the combo in HIV-negative Thai men and women aged 18 to 30 at average risk of becoming infected. Half received four “priming” doses of ALVAC and two “boost” doses of AIDSVAX over six months. The others received dummy shots. No one knew who got what until the study ended.

Thanad Yomha, a 33-year-old electrician from southeastern Thailand, said he didn’t expect anything in return for volunteering for the project.

“I did this for others,” Thanad said. “It’s for the next generation.”

All were given condoms, counseling and treatment for any sexually transmitted infections, and were tested every six months for HIV. Any who became infected were given free treatment with antiviral medicines.

Participants were followed for three years after vaccination ended.

The results: New infections occurred in 51 of the 8,197 given vaccine and in 74 of the 8,198 who received dummy shots. That worked out to a 31 percent lower risk of infection for the vaccine group. Two of the infected participants who received the placebo died.

The vaccine had no effect on levels of HIV in the blood for those who did become infected. That had been another goal of the study – seeing whether the vaccine could limit damage to the immune system and help keep infected people from developing full-blown AIDS.

That result is “one of the most important and intriguing findings of this trial,” Fauci said. It suggests that the signs scientists have been using to gauge whether a vaccine was actually giving protection may not be valid.

“It is conceivable that we haven’t even identified yet” what really shows immunity, which is both “important and humbling” after decades of vaccine research, Fauci said.

Details of the $105 million study will be given at a vaccine conference in Paris in October.

This is the third big vaccine trial since 1983, when HIV was identified as the cause of AIDS. In 2007, Merck & Co. stopped a study of its experimental vaccine after seeing it did not prevent HIV infection. Later analysis suggested the vaccine might even raise the risk of infection in certain men. The vaccine itself did not cause infection.

In 2003, AIDSVAX flunked two large trials – the first late-stage tests of any AIDS vaccine at the time.

It is unclear whether vaccine makers will seek to license the two-vaccine combo in Thailand. Before the trial began, the U.S. Food and Drug Administration said other studies would be needed before the vaccine could be considered for U.S. licensing.

“This is a world first which proves that vaccine development is possible,” said Dr. Supachai Rerks-Ngarm, the Thai Health Ministry official who oversaw the trial. “But this is not to the level where we can license or manufacture the vaccine yet.”

Mass-producing the vaccine, plus how to proceed with future studies, will be discussed among the governments, study sponsors and companies involved in the trial, Kim said. Scientists want to know how long protection will last, whether booster shots will be needed, and whether the vaccine helps prevent infection in gay men and injection drug users, since it was tested mostly in heterosexuals in the Thai trial.

The study was done in Thailand because U.S. Army scientists did pivotal research in that country when the AIDS epidemic emerged there, isolating virus strains and providing genetic information on them to vaccine makers. The Thai government also strongly supported the idea of doing the study.

Surprise, surprise.

The New York Times’ John Tierney reports on his blog today that a new book questions whether Masters & Johnson faked the conversion of gays and lesbians into happy heterosexuals. Ex-gay groups, like Exodous International, often use the Masters & Johnson study to say that the ability to turn gays into ex-gays has a scientific basis. Fail!

Book author Thomas Maier reports his findings in Scientific American:

“When the clinic’s top associate, Robert Kolodny, asked to see the files and to hear the tape-recordings of these “storybook” cases, Masters refused to show them to him. Kolodny—who had never seen any conversion cases himself—began to suspect some, if not all, of the conversion cases were not entirely true. When he pressed Masters, it became ever clearer to him that these were at best composite case studies made into single ideal narratives, and at worst they were fabricated.”

Gee. The grandparents of ex-gay conversion therapy made it up? Who would have thought?

During a visit to Africa on Tuesday, Pope Benedict reiterated the Catholic Church’s controversial anti-condom stance, and went as far as to claim that the use of condoms contribute to the spread of the AIDS epidemic.

“[AIDS] cannot be overcome by the distribution of condoms. On the contrary, they increase the problem.”

Let’s set aside for a moment that the basis of the Pope’s declaration is the religious belief that birth control is somehow abortive of human life. How can any man, particularly a man meant to bring spiritual enlightenment to millions around the world cling so stubbornly to a false belief that creates  widespread pain and destruction?

What the Pope’s declaration really reveals is a deep distrust and even disdain for modern science. There are statistics– statistics based on scientific principle– that prove condoms play no role in the spread of AIDS, but rather (and I know this is shocking) help prevent the disease’s transmission.

Anyone who claims otherwise is bearing false witness. Pope Benedict, of all people, should know better.

On a related note, I’m relieved to recall that during his stem cell announcement earlier this month, President Barack Obama took a distinctly different tack regarding science when he set the following goals:

“To ensure that in this new administration, we base our public policies on the soundest science; that we appoint scientific advisers based on their credentials and experience, not their politics or ideology; and that we are open and honest with the American people about the science behind our decisions.”

We know what abandoning science looks like– we’ve lived it for the past 8 years– and it’s not pretty. Thankfully we have a President as skeptical of skepticism as the Pope is of science.

The researchers, from the University of Provence, studied the current genetic makeup of people from modern-day England, France, Greece, Germany and Spain. The results of the study are reported in the journal New Scientist.

The scientists say they found that a gene variant which protects against HIV is missing among segments of the population in the countries they examined within the boundaries of the Roman Empire. Furthermore, the frequency of the missing gene, CCR5-delta32, is strongest closest to Rome and weakest the further one is from the center of the Empire.

The presence of the CCR5-delta32 gene is widely believed to offer protection from HIV.

The Roman Empire expanded outward from Rome over 1,000 years. In Italy, Greece and Spain, where the Roman occupation lasted the longest, between 0 and 6 percent of the population exhibit the gene.

But in Germany and England where Roman rule was shortest, between eight and 12 percent of the population have the CCR5-delta32 gene.

People in European countries never conquered by Rome have even greater percentages of the gene.

In their report, the University of Provence researchers say it is doubtful the genetic differences are due to breeding between Roman soldiers and local populations, since military accounts from the period suggest there was little sexual interaction between the two.

Instead, they speculate that the Romans carried a disease into the local populations that destroyed CCR5-Delta32.

In a separate study, scientists at the University of Liverpool also have been researching CCR5-Delta32 and believe it had been more prevalent among people in much of Western Europe, those populations could have better fended off bubonic plague, known as the Black Death, which swept Europe.

While we celebrate equal marriage, what implications does this report and other scientific studies on homosexuality have for the continued future of the gay comunity?

I have no objection to them in principle because I believe we should give others the same respect that we ourselves demand. That includes giving people wide latitude about living their lives as they see fit. If you really believe that you’re heterosexual deep down, and you want to take steps to help realize that identity, far be it from me to insist otherwise. I’ll let you be the expert on what you feel deep down, as long as you show me the same courtesy.

In fact, many ex-gays do not show me the same courtesy. I’ve had several tell me, “C’mon—deep down you know that being gay is wrong.” I know no such thing, and I resent it when other people tell me what I know “deep down.” So let’s make a deal: you don’t tell me what I know deep down, and I won’t tell you what you know deep down.

I’m not denying that people are capable of deep self-deception; indeed, I know it firsthand. For years I insisted that I was “really” straight, even though (1) I had gay feelings, (2) I had no straight feelings, and (3) I knew that people with gay feelings but no straight feelings are gay. (This, from someone who would later teach elementary logic.) Somehow, by not letting my thoughts “touch,” I could avoid drawing the feared conclusions from them.

Maybe ex-gays are engaged in similar self-deception; maybe not. The point is that it’s their feelings, their life, their decision to make. So I won’t oppose their efforts in principle.

In practice, I have at least three serious problems with ex-gay ministries.

The first is their tendency to promote myths about the so-called “homosexual lifestyle” by generalizing from some people’s unfortunate personal experiences. Ex-gay spokespersons will often recount, in lurid detail, a life of promiscuity, sexual abuse, drug addiction, loneliness, depression, and so on. “That is what I left behind,” they tearfully announce, and who can blame them? But that experience is not my experience, and it’s by no means typical of the gay experience. To suggest otherwise is to spread lies about the reality of gay and lesbian people’s lives. (The best antidote for this is for the rest of us to tell our own stories openly and proudly.)

The second problem is the ex-gay ministries’ abuse of science. Many of its practitioners are engaged in “therapy” even though they are neither trained nor licensed to do so; some of that “therapy” can cause serious and lasting psychological damage. Ex-gay ministries tend to lean on discredited etiological theories—domineering mothers, absent fathers, and that sort of thing. They also tend to give false hope to those who seek such therapy. By all respectable accounts, only a tiny fraction of those who seek change achieve any lasting success. Even then it’s unclear whether feelings, or merely behaviors, have been changed. While we shouldn’t reject individuals’ reports of change out of hand, nor should we pretend that their experience is typical or likely.

The third and related problem is that many ex-gay ministries promote not merely a “change,” but a “cure.” “Cure” implies “disease,” which homosexuality is not. Insofar as ex-gay ministries promote the long-discredited notion that homosexuality is a psychological disorder, I oppose them. (“Spiritual” disorders are another matter, but then we’ve left the realm of science for that of religion. Ex-gay ministries have an unfortunate habit of conflating science, religion, and politics.)

I am not at all threatened by the notion that some people can change their sexual orientation, if indeed they can. In reality, it seems that at best only a small number can do so, and only with tremendous effort. But if they can, and that makes them happy, good for them. I’m confident enough in my own happiness that I need not doubt theirs.

Nor do I feel the need to insist that I was “born this way.” Maybe I was, maybe I wasn’t. What I can say with confidence is that these feelings are a deep and fulfilling part of who I am, and I see no reason to mess with them. Quite the contrary.

So when ex-gays announce, from billboards and magazine ads, that “Change is possible,” I say: Possible? Maybe. Likely? No. Desirable? Not for me, thanks.

Alas, the article was referring to actual insects, the annoying little ones that remind you to throw away overripe bananas. Apparently, some researchers at Penn State University have discovered that by getting groups of male flies “drunk” with alcohol fumes, they can induce homosexual behavior. (Just like frat boys.) They observed this behavior in a small transparent chamber, which they called—I am not making this up—a “Flypub.”

According to newscientist.com,

“The first time they were exposed to alcohol, groups of male flies became noticeably intoxicated but kept themselves to themselves. But with repeated doses of alcohol on successive days, homosexual courtship became common. From the third day onwards, the flies were forming ‘courtship chains’ of amorous males.”

Yes. And by the fourth day, they were redecorating the Flypub in sleek mid-century modern furniture. By the fifth day, they were serving Cosmopolitans and debating the relative fabulousness of Martha Stewart’s new Wedgwood line at Macy’s. And so on.

The article continues,

“[Lead researcher Kyung-An Han] argues that the drunken flies provide a good model to explore how alcohol affects human sexual behaviour. While the ability of alcohol to loosen human inhibitions is well known, it is difficult for scientists to study.”

Of course it is. Imagine the grant application:

“Describe the proposed methodology.”

“Um, well, I’m going to get a bunch of college students drunk and naked, then record their behavior.”

Sounds like a shoo-in for funding, no?

It’s not that I doubt the merits of such research. Granted, I’m far more interested in figuring out how to keep fruit flies out of my kitchen than how to make them horny. Still, I appreciate the value of scientific inquiry—all else being equal, the more we know about the world, the better.

My problem arises when people start using these studies to draw conclusions about human romantic behavior. While Han has warned against such inferences, other researchers and commentators have not been so cautious.

For example, when Austrian researchers in 2005 genetically manipulated a female fruit fly to induce homosexual behavior, Dr. Michael Weiss, chairman of the department of biochemistry at Case Western Reserve University, told the International Herald Tribune, “Hopefully this will take the discussion about [human] sexual preferences out of the realm of morality and put it in the realm of science.”

I hope it does no such thing. For two reasons: first, because human sexuality is far richer and more complex than fruit-fly mounting behavior. (Fruit flies don’t pout if you don’t call the next day—or so I’m told.)

Second, and more generally, because science and morality tell us different things. Science tells us something about why we behave as we do. It does not tell us how we SHOULD behave, which is the domain of morality. Science cannot replace morality or vice-versa.

To put the point another way: while scientific study can reveal the biological origin of our feelings and behaviors, it can’t tell us what we should do with them. Should we embrace them? Tolerate them? Change them? Those are moral questions, and simply observing fruit flies—or humans, for that matter—is insufficient to answering them.

But can’t these studies prove that homosexual attraction is “natural”? Not in any useful sense. Specifically, not in any sense that would distinguish good feelings and behaviors from bad ones. Discovering the biological origin of a trait is different from discovering its value.

Beyond conflating morality with science, popular commentators on these studies have an unfortunate tendency toward oversimplification.

Consider last year’s fruit-fly study at the University of Illinois, which the gay newsmagazine The Advocate announced with the headline, “Study finds gay gene in fruit flies.”

Except that it didn’t. What the study found was a genetic mutation in fruit flies that rendered them essentially bisexual. Scientists could then switch the flies’ behavior between heterosexuality and homosexuality through the use of synapse-altering drugs.

In other words, the study neither found a “gay gene” in fruit flies nor answered any questions about how hardwired or malleable human sexual orientation might be.

Meanwhile, one fruit fly who participated in the Penn State study released the following statement: “Dude, I was so drunk that day—I don’t know what happened!”