An unprecedented admission from its intellectual godfather is sending shock waves through the animal rights movement this week. In a documentary broadcast Monday night on British television, Princeton Professor Peter Singer acknowledged that some medical testing involving animals — traditionally pegged as an animal rights no-no — is in fact morally acceptable. Coming from virtually anyone else, such a statement wouldn’t be much of a story. (Most people understand that some research on living creatures is and has always been essential to scientific advancement.) But Singer is the author of Animal Liberation — the 1975 philosophical treatise that inspired generations of animal rights zealots, including People for the Ethical Treatment of Animals (PETA) founder Ingrid Newkirk.

Singer’s admission came when Dr. Tipu Aziz — whose research using primates has led to treatments for people suffering from Parkinson’s disease — told him on camera that “to date 40,000 people have been made better with [the procedure Dr. Aziz has developed], and … I would guess only 100 monkeys were used at a few laboratories.”

Singer replied:

Well, I think if you put a case like that, clearly I would have to agree that was a justifiable experiment … It is clear at least some animal research does have benefits. I would certainly not say that no animal research could be justified and the case you have given sounds like one that is justified.

This is a far more reasoned approach than the intellectually bankrupt absolutism promoted by Singer’s fellow animal activists at PETA and its pseudo-medical affiliate, the Physicians Committee for Responsible Medicine (PCRM). In 2004 a PETA vice president told Fox News’ Neil Cavuto that “none of this research [on animals] is necessary.” And on its website, PCRM claims that “the profound differences in anatomy, physiology, and biochemistry between humans and animals make animals poor models for humans.” Apparently no one told them about the life-saving treatments for AIDS, cancer, Alzheimer’s disease, and polio (among others) that have been developed with the help of lab animals.

Singer’s detractors have been quick to write off his apostasy as irrelevant to the larger animal movement. But even in their dismissal, many have echoed Singer’s divergence with animal rights radicals. Case in point: Rutgers Law professor and prominent vegan activist Gary Francione, who — besides calling PETA “more of a cult than a political and social movement” — tells National Review Online‘s Wesley Smith today:

It simply doesn’t matter what Singer said. He is the leader of the cult. I suspect that other than possibly causing [Ingrid] Newkirk to announce an “I’d rather go naked than have Parkinson’s” campaign to further fill PETA’s coffers, and my getting hate mail from “animal rights” people who think I am a heretic for criticizing Singer, nothing much will happen.

Francione is probably underestimating the impact of Singer’s about-face. Smith notes, for instance, that Singer’s “pro-research statement will surely undermine the general liberationist meme that animal experimentation is useless [and] should exacerbate the movement’s ongoing splintering.” But he’s right about PETA. As we told NRO, “As long as there is money to be made, PETA will adapt. Heck, they might even start protesting outside Singer’s Princeton office until he sees the ‘error of his ways.'”