PRINCETON ― The moral progress of a society, it has often been said, can be judged by how it treats its weakest members. Individual chimpanzees are much stronger than human beings, but as a species, we can, and do, hold them captive, and essentially helpless, in zoos and laboratories. Equally subject to human power are the animals that we raise for food, among them sows confined for their entire pregnancies ― four months per pregnancy, two pregnancies per year ― in stalls too narrow for them even to turn around.

In this sense, 2013 got off to a good start in Europe and the United States. On Jan. 1, a European Union directive came into effect banning the use of individual sow stalls from the fourth week of pregnancy until one week before the sow gives birth. Millions of sows must now have the elementary freedom not only to turn around, but to walk. Nor can they be kept on bare concrete without straw or some other material that allows them to satisfy their natural instinct to root. By the end of January, 20 of the 27 EU member states were at least 90% compliant with the directive, and the European Commission was preparing to take action to ensure full compliance.

Meanwhile, in America, active campaigning by the Humane Society of the U.S. has led to about 50 major pork buyers announcing that they will phase out their purchase of pork from suppliers who use sow stalls. (Some, including Chipotle and Whole Foods, already have.)

Still, Europe is far ahead of the U.S. on farm-animal welfare. The ban on sow stalls there continues the progress made to ameliorate the most extreme forms of animal confinement.

Individual stalls for veal calves were the first to go, in 2007. Last year, the standard battery cage for egg-laying hens was banned, ensuring somewhat better conditions for hundreds of millions of hens (though they can still be kept in cages that severely restrict their movement).

The new standards are compromises that are premised on the assumption that Europeans will continue to eat animal products and do not wish to see a sharp rise in the cost of their food. Predictably, therefore, animal-welfare advocates are not ― and should not be ― satisfied, even if, as the European Commission’s scientific and veterinary advice indicates, the new standards will reduce animal suffering.

Another European directive came into effect on Jan. 1, banning medical research on chimpanzees. It went unnoticed, because there has been no European medical research on chimpanzees since 2003. During the past 20 years, other countries have also stopped using chimpanzees for medical research; indeed, only the U.S. and Gabon continue to do so, with the U.S. by far the larger user.

Last month, the National Institutes of Health, the U.S. government agency responsible for biomedical research, approved a report recommending the cancelation of the majority of NIH-funded projects involving invasive biomedical research on chimpanzees. The report also recommends that most of the chimpanzees owned or supported by the NIH should be “retired” from research and moved to sanctuaries.

The NIH will retain only one colony, comprising roughly 50 chimps, and any research carried out on these apes will have to be approved by an independent committee that will include public representation. The report also recommends special requirements for keeping the remaining chimps: housing in groups of at least seven, with a minimum of 1,000 square feet per chimp, room to climb, and opportunities to forage for food. The NIH action still needs to be ratified by the director, Francis Collins.

With billions of animals still leading miserable lives on factory farms, more space for pregnant sows and the release from labs of a few hundred chimpanzees may not seem like much to cheer about. But the larger picture is worth celebrating. For centuries, humans in industrialized countries have treated animals as units of production, rather than as sentient beings with a moral status that requires us to take their interests into account. (In more traditional societies, relations between humans and animals have often been closer, but not always better for the animals.)

The struggle to liberate animals from oppression is a moral campaign comparable to the struggle to end human slavery. Indeed, the enslavement of animals, for labor and for food, is more pervasive and more central to our way of life than the enslavement of other humans ever was. With some isolated and short-lived exceptions ― for example, in India under the Emperor Ashoka and in Japan under the Tokugawa shogun Tsunayoshi ― laws to protect animals from cruelty are less than 200 years old.

It is therefore bound to be a long struggle. But, if the gains made so far seem to be dwarfed by the wrongs that humans continue to do to animals, we can find hope in the fact that, as January’s developments show, the pace of change is accelerating perceptibly.

By Peter Singer

Peter Singer is professor of bioethics at Princeton University and laureate professor at the University of Melbourne. ― Ed.

(Project Syndicate)