The U.S. is home to an estimated 1,724 captive chimpanzees, whose living conditions vary widely. (Photo: Eric Kilby/Flickr)

Chimpanzees are humans' closest living relatives, sharing about 99 percent of our DNA, yet we often don't treat them like it. Not only are we pushing them toward extinction in the wild, but we have a long history of mistreating them in captivity, too, whether as pets, entertainers or research subjects.

The apes are widely considered an endangered species, and in 1990 the U.S. government added wild chimpanzees to its endangered species list. It omitted captive chimps, however, and for the past 25 years they've been left with the less protective status of "threatened." This strange distinction, the only "split listing" in the history of the U.S. Fish and Wildlife Service, was allowed so the National Institutes of Health could continue funding medical research on captive chimps.

But that's finally changing. On June 12, the U.S. Fish and Wildlife Service declared that all chimpanzees — both in the wild and in captivity — are endangered. The move comes in response to a 2010 petition by several groups, including the Jane Goodall Institute and the Humane Society of the United States, that urged the U.S. to recognize all members of an endangered species as endangered, regardless of where or how they live. This may have little direct effect on the health of Africa's wild chimp populations, but it could make a world of difference for those living in captivity across the Atlantic.

"Extending captive chimpanzees the protections afforded their endangered cousins in the wild will ensure humane treatment and restrict commercial activities under the Endangered Species Act," FWS director Dan Ashe says in a statement. The new ruling prohibits invasive research on 733 captive chimps still in U.S. labs, the Humane Society adds, including privately funded research that wasn't affected by earlier federal efforts to limit support for such studies. It should also curb the use of chimps as pets or for entertainment, especially the trade of captive chimps across state lines.

"It's another barrier to using chimpanzees, providing momentum to our efforts to retire these animals" from research, says Jonathan Lovvorn, chief counsel for the Humane Society of the United States, in a press release. "Hopefully, this sends a strong signal to not even attempt to use these animals."

The U.S. Endangered Species Act does not allow captive animals to be given a separate legal status from their wild counterparts, the FWS notes, so this move was all but inevitable.

"The decision responds to growing threats to the species and aligns the chimpanzee's status with existing legal requirements," Ashe says. "Meanwhile, we will continue to work with range states to ensure the continued survival and recovery of chimpanzees in the wild."

Wild chimps still exist in 22 African countries, where their remaining enclaves are increasingly at risk from fast-growing human populations. Poaching and habitat fragmentation are two of the most dire threats, but some chimps are also still taken from the wild for the pet trade. As many as 1 million existed in the wild a century ago, but they now number somewhere between 172,000 and 300,000.

After receiving the petition from animal-rights groups, the FWS proposed listing all chimpanzees as endangered in June 2013. It has taken two years, but animal advocates are celebrating the move as a breakthrough not just for chimpanzees, but also for our own species' moral standing.

"All at the Jane Goodall Institute wish to congratulate the U.S. Fish and Wildlife Service on the decision to include captive chimpanzee in the endangered listing along with wild chimpanzees," renowned primatologist and U.N. Messenger of Peace Jane Goodall says in a statement. "This will be enormously beneficial to individuals in inappropriate captive conditions. As such it is a tremendously significant decision which will be welcomed by everyone concerned with the well-being of our closest living relatives. Thank you for helping to make their world a better place."

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Russell McLendon ( @russmclendon ) writes about humans and other wildlife.

U.S. grants new protections for captive chimpanzees
The U.S. has officially reclassified all chimpanzees — both in the wild and in captivity — as an endangered species.